5.1.1 A Definition of Ecological Sustainability

Agricultural practices today pose a serious challenge to the maintenance and protection of natural, healthy functioning ecosystems. In the following analysis, various aspects of agricultural practices are evaluated from the perspective of ecological sustainability. Soil properties (health), pesticides, fertilizers, non-point source pollution, and biodiversity are each examined on a local scale in relation to the Upper Valley region as well as in broad terms.

In order to establish the overall ecological sustainability of agricultural practices in the Upper Valley, we must first define sustainability with respect to ecology. Ecological sustainability maintains productivity with minimal inputs into the ecosystem and involves closing of the nutrient cycling loops at least within the Upper Valley region if not beyond this system. In order to achieve these goals of minimal inputs and complete nutrient cycling, the following criteria must be attained:

5.2.1 Introduction

Soil is often an underestimated natural resource. What most people consider "dirt" is actually a thriving, yet delicate ecosystem. Crop production, forests, myriad microorganisms, among other things, depend upon this seemingly ubiquitous resource. The apparent infinite availability of soil is misleading, and the assumption has taken shape in its mismanagement. For farmers, soil is the substance which sustains and supports the crops and livestock upon which their livelihoods depend. Therefore, soil fertility is paramount and the Upper Valley is privileged to have such a wealth of fertile land for agriculture. Soil fertility is defined as "the status of a soil with respect to its ability to supply elements essential for plant growth without a toxic concentration of any element." (1) However, farmers are concerned with their soil's production, which encompasses the idea of soil fertility and soil management--using lands in such a way as to maximize yield. Sustainable soil management attempts to strike a balance between the long-term maintenance of soil fertility and economically feasible crop production. In this section, the main components of soil and it’s properties are discussed, in addition to the current state of soil in the Upper Valley and what measures may be taken to ensure its sustainability.

5.2.2 Physical Properties of Soil

• Soil Texture

Particle size and spacing, although seemingly trivial, is perhaps the most important factor determining the properties of soil. There are three classes of particle size, listed in order of increasing diameter: clay, silt, and sand. The combination of these three particle types in soil determine a soil's texture and affects it's cation exchange capacity (see below), water filtration/retention capacity, the size and amount of air pores, etc. While the description of a "best" soil remains to be defined by the types of plants which inhabit them, fertile crop soils often have a good combination of different soil particle sizes which maximize filtration and nutrient retention. The relative combination of soils particle sizes determines a soil’s classification as either a sand, silt, clay or loam soil--a soil defined by a mixture of all three soil particle sizes. Loams make up most of the soils of agricultural importance.(2)

• Soil Structure

In addition to soil texture, the aggregation of soil particles is especially critical to soil fertility. Aggregation refers to the manner in which individual soil particles are held together in clusters of different shapes and sizes. Soil depth will affect the size of aggregates--aggregates usually become larger with an increase in depth. For farmers, the crumb-like structure is the most significant aggregate. "Crumb structure" improves soil porosity, aeration, and the ease of tillage, while reducing the density of the soil--the bulk density (see below). Maintaining low soil density is critical for cultivated lands, for it is directly linked to problems with compaction. If a soil experiences increased compaction, the overall pore space is reduced, decreasing a soil's ability to retain water and air needed for plant growth. Furthermore, roots are less able to penetrate through the dense, compacted soil of a plow pan.

Aggregation of particles depends upon two things: the attraction of the individual particles, and the binding properties of organic matter. While farmers cannot control a soil's innate texture, governing individual particle attraction, they can affect the amount of organic matter in the soil. With adequate amounts of organic matter, crumb-structure is maintained. Overall, it is best to avoid "excessive cultivation [which] accelerates breakdown of organic matter and increases the potential for compaction, causing bulk density to go up and many of the advantages of good crumb structure to be lost." (3)

• Bulk Density

Bulk density refers to the mass of a unit volume of soil, including both solids and pores. (4)

High bulk densities indicate that a soil’s ratio of solids to pore space is high; this is the case in comp-

acted soils. In such extremely compacted soils, there are essentially no macropores, and root growth is greatly impaired. (5) Excessive cultivation, which includes numerous field passes with heavy machinery, and constantly plowing at the same depth are among the factors leading to increased bulk densities and compaction. Maintaining adequate levels of organic matter in the soil will relieve these effects. The Figure 5-1 reveals the effects of tillage and compaction on crop yield over a three year period.

Figure 5-1. Influence of Tillage and Compaction upon Crop Yield

(Source: Brady, Nyle. The Nature and Properties Of Soil. p. 112.)

• Cation Exchange Capacity

Plant roots pervade the soil in order to reach water and essential nutrients necessary for plant growth. Most nutrients, such as potassium, calcium and nitrate exist in the form of ions dissolved in solution. These minerals are at risk of being leached out of the soil if plants do not take them up through their roots. However, soil particles have charged surfaces which bind these ions, retaining them in the soil. A soil's ability to hold on to these ions is termed the cation exchange capacity (CEC). The higher the CEC, the more nutrients available to plants and less of a risk of nutrient loss from leaching. Soils higher in clay content have greater CECs due to the large surface area of clay particles. Sandy soils, on the other hand, have little to no CEC. Humus, the form of broken down and slightly decomposed organic matter, "is many times more effective than clay in increasing CEC since it has a much more extensive surface area-to-volume ratio (hence more adsorption sites) and because it is colloidal in nature." (6)

• Soil Acidity and pH

A soil's pH serves as an indicator of its acidity or alkalinity. The pH is a measure of the amount of hydrogen ions and will help to determine a soil’s fertility. A low, acidic pH indicates a larger amount of hydrogen ions. If a soil’s pH is too low, the hydrogen ions will replace the CEC sites previously held by the important base cations such as calcium, magnesium and potassium, leaching them through the soil. In addition, certain microorganisms cannot function if a soil is too alkaline or acidic. Earthworms and other microbes are extremely significant in the processes or organic matter breakdown and nutrient recycling. Plants, similar to creatures in the soil, have specific pH ranges dictating their ability to grow and thrive. Processes such as liming can help to restore the base cations to the soil, elevating soil pH.

Organisms in the soil are largely responsible for the breakdown and synthesis of organic molecules in soils, especially humus--highly decomposed organic matter. While the most significant contribution of the soil organisms is their ability to decompose organic matter, some bacteria and microbes play a role in nitrogen fixation and transformation of inorganic compounds into substances useful to the plant. (7) Earthworms, however, are the most important of the soil macroanimals. (8) By ingesting organic matter and soil, the materials are ground up within the worm’s cavity, and subject to digestion and transformation by enzymes. Subsequently, the digested material (casts) becomes more available as nutrients for plants. Furthermore, the holes left in the soil by the earthworms aerate the soil, creating more pore spaces. On heavily cultivated lands, the organism populations decline, due to the increased compaction of the soil. Farmers may use the populations of a visible soil organism such as an earthworm as an indicator of soil health; if soils are poorly aerated, drained or too acidic, earthworms will be scarce. In healthy, arable fields, more than 500 earthworms may be present per square meter, compared to very acidic soils, which may contain an average of fewer than one organism per square meter.(9)

Organic matter is the most critical component of a healthy soil. The portion of the soil profile characterized by organic matter and humus is the most active layer biologically as well as the most important ecologically. (10) Specifically, organic matter is comprised of leaf litter, plant and animal residues, etc. Organic matter supplies and renews much of the nutrients in the soil. It will increase a soil’s CEC, helping to retain the valuable elements such as calcium and potassium. Structurally, organic matter retains the crumb-like structure that is important on cultivated lands. Moreover, pore spaces increase, leading to habits for organisms and maintaining healthy, aerated soils. Soils high in organic matter achieve a perfect balance between water retention and drainage. Clearly, the application and maintenance of organic matter in soil is paramount to it’s fertility and sustainability.

With respect to agricultural sustainability, organic matter is the primary component of soil which farmers can manipulate. In addition to the benefits enumerated above, soil organic matter helps to control erosion on farmland by acting as a stabilizing substance to which particles can bind. However, soils under cultivation typically lose organic matter, compromising soil fertility: "crumb structure is lost, bulk density begins to rise, soil porosity suffers, and biological activity declines." (11) By concentrating soil management techniques around organic matter, farmers should be able to increase and sustain their soil's fertility. "More organic matter usually means a more productive soil." (12)

5.2.5 The Upper Valley

• Erosion

Along the river, erosion in the Upper Valley poses a problem. This year, some marginal lands have lost 20-40 feet along their banks. (16) Sites where land slopes down toward the river are particularly susceptible to soil loss from rains and river flooding. In addition, wave action from wind and even the wake created from motor boats constantly bombard the shoreline, removing bits of land on the banks over time. In areas where trees have either fallen or been cleared from the riverbank can experience erosion on as much as 60% of its area. (17) The concave banks along the river are severely eroded, receiving the brunt of the river’s flow. In a 1992 study by the Grafton County Conservation District, all 89 miles of the river in the county were inventoried and classified by the amount of erosion damage. In places classified as "moderate" and "severe" were on agricultural lands with high, steep banks. The "stable" and "slight" erosion areas were primarily forested slopes, low banks or sites of erosion control efforts. (18) Careful planning of sites along the Connecticut can help to prevent the loss of soil into the river (see suggestions below).

Away from the river, erosion is minimal. On Walhowdon farm, Howard Patch practices strip farming where he alternates rows of corn and grass across hillsides to minimize erosion. (19) On dairy farms, the pastures are usually on steeper lands and wind erosion is abated by the hillsides and mountains. Furthermore, the grass cover holds much of the soil together. However, some farmers in the area grow their own feed for the cows, which when harvested can expose land to wind and rain erosion. On Larry Martin’s farm, he grows corn for his livestock. Once the corn is harvested, he plants winter rye to prevent erosion and to keep the fields green. (20) Overall, compared to the large farms in the Great Plains and out west, only erosion for lands along the Connecticut River seems to be a primary concern.

• Soil Compaction

• Maintenance of Fertility

Largely, farmers seem to plant cover crops in order to sustain their soil’s fertility. Winter rye and clover are popular cover crops in the region. (26) In addition, animal manure are widely used. Jake Guest composts hen manure with saw dust, because it adds a large supply of nitrogen to the soil.

5.2.6 Soil Management Suggestions

There are many different ways in which a farmer can sustain the fertility of his/her soils. Practices which minimize soil erosion, compaction and exhaustion must be incorporated into farm management programs so that farmers may continue to use their lands productively for many years. Habits such as crop rotation, contour plowing, green manure, strip cropping, grass waterways, conservation buffers, conservation tillage, etc., are among the practices that farmers should employ to maintain soil health and to avoid the adverse effects of cultivation.

• Continued Use of Crop Rotation, Green Manure, and Composting

Cover crops, also referred to as "green manure," is an extremely valuable source for the replenishment of soil organic matter, as many farmers in the Upper Valley realize. The biomass may be degraded or left as a covering to protect soil from wind and water erosion. Using crop residue in order to return nutrients to the soil is another valuable practice. However, there are some concerns with potential pest and disease problems as well as properly timing to incorporate the residue into the fields. Composting itself has been a large consideration as a supplement to animal manure recently. Lawn clippings, certain food wastes, agricultural by-products among other materials may be decomposed under controlled conditions and used as supplemental materials which return nutrients and organic matter to the soil. The Dartmouth/Town of Hanover Composting Facility may prove to be a valuable source of composted materials for farmers.

• Conservation Tillage and Compaction

Conservation tillage evolved as an idea in which reduced tillage is necessary to prepare fields and decrease the number of field passes with heavy machinery. This would help to minimize compaction and deterioration of organic matter on cultivated land. Conventional tillage has often involved plowing, disking and harrowing in order to prepare the ground for planting. Each process has it's own purpose, yet the negative effects upon the soil are enormous. (27)

Compaction, especially in moist climates, poses a problem on cultivated lands. As a rule, farmers should avoid tilling, plowing, or any field work involving heavy machinery when the soil is saturated after rains or floods; otherwise, soil may be compacted to a blocky, clod-like dense texture. Subsoilers may be used to break up the soil every few years in the face of increasing compaction. However, using lighter machinery and reducing trips across the field to begin with, will reduce compaction of farmland soils, helping to sustain soil fertility and productivity.

There are several disadvantages to conservation tillage which have yet to be solved. Probably the largest concern for farmers is the cost of the special machinery necessary to plant the crop residues, as well as possible pest infiltration--insects are attracted to the abundant resources which remain in the soil. Other concerns are:

• Erosion

Erosion is a significant concern for farmers along the river. The Upper Valley cannot compete with the midwest with respect to wind erosion, but hillside and river erosion still pose potential threats. Contour plowing helps to relieve hillside erosion. By planting on the contours of hills, and using a strip crop between tiers, soil erosion may be lessened.

Conservation buffers are powerful erosion minimizers, especially for farming systems along rivers like the Connecticut. The Conservation Reserve Program, a division of the USDA, provides a mechanism to restore marginal lands and use farm acreage as a natural "buffer" to erosion and degradation. Started in 1985, the Conservation Reserve Program "encourages farmers to voluntarily plant permanent areas of grass and tress on land that needs protection from erosion...". (28) Filter strips are areas of grass or other vegetation planted along sloping points of fields which border bodies of water. These buffer regions would be especially valuable in order to abate the erosion along the Connecticut River. Any hardy grasses or vegetation along sloping lands would help to reduce soil loss into the river, anchoring the soil in place with the hardy grass roots. Similarly, grass waterways are channels planted in order to prevent soil erosion into lakes or rivers after heavy rains. Overall, buffers would reduce soil erosion, provide filtration of harmful pollutants, and provide shelter for the diversity of wildlife. If farmers agree to take land out of production they could be paid a certain percentage of what that land would be earning if it were farmed. Consequently marginal lands are saved, soil erosion--a potential economic burden is minimized and soil fertility is restored.

• More Soil Testing

One of the largest obstacles to efficient use of resources in the Upper Valley is the lack of available man-power for soil testing services. (29) Farmers must be aware of the physical state of their soils--the nitrogen and phosphorus contents, the pH, and degree of compaction, etc.--to be able to better manage their land. However, there are not enough professionals in the area nor established services available to farmers to obtain this information. The extension agencies’ agricultural educators cannot be expected to handle this responsibility on their own. It is extremely important to integrate other sectors, including economics and the community, in order to realize the value of soil testing and the need for these services to make farming in the region more sustainable.

5.2.7 The Economics of Soil Conservation

Clearly, the above conservation mechanisms help to maintain soil organic matter, nutrients, water retention while minimizing compaction and eventually increasing crop yields. Yet, many people worry that investing in conservation methods such as buffers, or more expensive machinery for tillage, etc., is too costly--which may be true in the short term. However, $1 invested in conservation practices returns $1.30 to $3.00 in increased crop yields (depending upon the specific crop, location, season, etc.). (30) Furthermore, erosion can be extremely subtle. With each raindrop and gust of wind, a little bit of topsoil may be lost. Counting up each raindrop and wind gust leads to large soil losses over time. The cost of adverse effects of soil erosion such as the need to dredge rivers, build levees and restore property damage after erosion, adds up quickly. Again, $1 invested may save between $5 and $10 spent to fix the problems caused by erosion--saving farmers and society money. (31)

The history of farming in the Upper Valley should be an admonishment to farmers today. Two hundred years ago, farming was viable -- each farmer sought to supply himself and his family with food and shelter, while preserving the integrity of the land. In the face of increasing productivity and a peak in population in mid-1800s, soil fertility began to decline and everyone headed west. Today, the midwest doesn’t have much room for people seeking greater economic gains in farming. It is true that technology and environmental awareness has improved in the 20th century, especially in the last 20 years. However, one cannot take our renewable resources for granted. We must notice that our resources are susceptible to exhaustion and depletion, as evidence from the history of this region.

Pesticides, defined broadly, are those chemicals that are designed to kill organisms which humans consider undesirable. (32) These organisms include various insects, plants, fungi, nematodes, etc. They may be broad-spectrum agents which are toxic to a range of organisms or more selective in their target species. Pesticides also vary considerably in their persistence, the length of time they remain in the environment, and in their ability to bioaccumulate, or to increase in concentration as they make their way up the food chain. The type of pesticide used determines the extent of its environmental impact. In general, pesticides which persist in the environment and can be bioaccumulated cause more damage to humans and wildlife. Table 5-1 summarizes the major classes of current pesticides. (33):

In terms of preserving the integrity of the environment for an infinite number of future generations, the use of pesticides is not sustainable. Pesticide use can have a number of detrimental effects on both humans and wildlife (particularly birds and aquatic organisms). Approximately 67,000 cases of human pesticide poisonings are reported to the American Association of Poison Control Centers each year. (34) The health effects of pesticides depend greatly on the type of pesticide to which a person is exposed, but the possible health risks include a number of neurological disorders, sterility, birth defects, hypersensitivity resulting in anaphylactic shock, certain forms of cancer, as well as death. Children are even more sensitive to many chemical pesticides than adults. In 1993 a study by the National Academy of Sciences found that the legal limits for pesticide residues in food may need to be reduced 1000 times in order to adequately protect children.(35)

Pesticide use, particularly DDT and other chlorinated hydrocarbon pesticides, has been directly linked to reproductive failure in many raptorial birds such as the peregrine falcon, osprey and the bald eagle, some of which are now endangered. Even though the use of these pesticides is now banned, recent tests by the EPA found that 99% of tested freshwater fish had detectable amounts of DDT in their system. (36) Organophosphates, the class of pesticides that largely replaced chlorinated hydrocarbons have also been found to negatively impact wildlife. Many studies link organophosphates to large waterfowl die-offs in the United States (see White et. al. 1992 and Stone and Gradoni 1985). Pesticides can also potentially poison livestock. The estimated economic damage caused by the poisoning of dairy cattle by pesticides in the US. is $900,000 per year. (37)

Some pesticides have a high potential for leakage into the watershed, where they can pollute the water supply. A national study done by the EPA in 1990 found that 10.4% of community wells and 4.2% of rural domestic wells had detectable levels of at least one of 127 pesticides which were tested. (38) Because few microorganisms can actually break down pesticides, they can remain in these systems for long periods of time.

It is ironic that pesticide use can actually lead to increased problems with insect pests. The use of broad-spectrum pesticides, those which are toxic to many species, can kill natural predators and parasites of the target pest. This sets up a situation in which the pest can make a strong comeback after being initially controlled. The reduction of natural predators and parasites can also create pests out of organisms whose populations were previously under control.

Using chemical pesticides may also ultimately prove to be more expensive in the long run than other methods of pest control. Consider that since 1950, 520 insect species have developed genetic resistance to one or more pesticides, and 17 insects have developed resistance to all major pesticide classes. (39) Many insects can develop resistance in as little as 5-10 years, forcing chemical pesticide developers to create new chemicals which are sometimes more expensive than their predecessors.

There are a number of reasons why farmers have come to depend on pesticides and no discussion of pesticide use can ignore some of the positive contributions that pesticides have made to agriculture. By using chemical inputs to control unwanted pests food supplies can be increased and food costs lowered. By far the most compelling reason why today's farmers continue to use pesticides, however, is that pesticides can increase a farmer's profit margin. Indeed, some of the farmers which were interviewed as case studies for this report expressed the opinion that they could not continue to keep their business viable without using chemical pesticides. There is certainly some truth in this statement because without changes in government agricultural policy which encourage pesticide reduction and an expanded knowledge base of alternative pest control mechanisms which are economically feasible complete elimination of pesticides would certainly be very difficult.

In the United States, more crops are lost to pests today (37%) than in the 1940's (31%), despite a 3300% increase in the use of chemical pesticides. (40) There are several current trends to be aware of in U.S. agriculture which increase our dependence on chemical pesticides. For several decades the average size of a farm has been increasing while the overall number of farms has decreased. Managing a farm that does not rely on chemical input is much more challenging when the farm size increases. There has also been an increase recently in the number of part-time farmers who often do not have enough time to use alternative methods of pest control. Finally, because of the temporal separation of today's farmers from pre-pesticide agriculture there is a perception that farming without pesticides can't be made to work.

All of the above trends also apply to the state of agriculture in the Upper Valley. In general, the farmers of the Upper Valley have been very aware of the environmental effects of pesticide use. According to the 1992 Agricultural Census of New Hampshire and Vermont, 36.8% of the farms in the Upper Valley (Grafton and Windsor counties in Vermont and Orange and Sullivan counties in NH.) use some form of chemical pesticide on their farm. (41) Herbicides used in the Upper Valley include calachlor, cyanazine, atrazine, chloroacetamide (and the relatively new "dual II magnum") and pendimethalin. Captan and imidan two other pesticides which are commonly used are . Upper Valley farmers have both reduced the amount they apply and switched to less toxic pesticides as these became available. However, given the variety of negative environmental impacts and health risks which are still associated with pesticide use, every effort should be made to reduce the use of chemical pesticides on farms in the Upper Valley where it is economically feasible.

Pests are a natural part of an agroecosystem- they will never be completely eliminated and the artificially high resource base of an agricultural field will tend to increase their abundance. The goal of pest control thus becomes keeping the populations of pests below an economically viable level in a way that does not negatively affect the environment. The table below summarizes alternative pest management strategies and their relative strengths and weaknesses:

Corn is commonly grown in the Upper Valley to be used as a component of mixed ration cattle feed. There are several alternative mechanisms which can be combined to control pests and eliminate or reduce the use of chemical pesticides. Annual crop rotation is probably the most important and several crops could be introduced into a crop rotation system in order to increase overall crop resistance to pests and weeds. Alfalfa simultaneously fixes nitrogen, suppresses weed growth and aids in soil conservation and can be a valuable cash crop. Oats also aid in suppressing weed growth, increasing soil conservation, and they have a low production cost. Furthermore oats can provide grain and straw to be sold or used in a livestock operation. Other methods of insect control for corn include using corn which is resistant to corn borer and cinch bug if possible and using sex attractants to control rootworm. These alternative methods could eliminate the use of pesticides altogether and have been shown to only increase production costs by approximately $10/ha. (42)

(Source: Jean Dyke. Personal Interview. 24 April 1998.)

5.3.7 Policy Recommendations

• Programs to reduce pesticides - Conservation Resource Program

The state and federal governments should work together to develop programs encouraging practices which reduce the amount of pesticides that are applied to farmland. One example is the Conservation Resource Program of the US. Department of Agriculture, which aids farmers in the creation of various "buffers" on their farms. These buffers include riparian buffers, filter strips, grassed waterways, contour grass strips, shallow water areas for wildlife, wellhead protection areas, field borders, alley cropping, herbaceous wind barriers, vegetative barriers and streambank plantings. In return for setting aside land in a buffer the farmer receives up to 100% of the value of cropping the land from the government.

• Integrated Pest Management

The development of Integrated Pest Management programs should be a priority for the Department of Agriculture in both New Hampshire and Vermont as a reachable intermediate step towards the final goal of eliminating pesticide use altogether. Also, the scope of the programs currently in existence should be expanded to include all farms in the Upper Valley. Because many pests are common to both states, a jointly funded commission with representatives (farmers, chemical manufactures, companies which develop biological control agents, government agency representatives) from both states could work together to develop permanent, sustainable pest control practices. This joint agency would of course require funding, but the short-term costs of its creation and implementation would be balanced by long-term gains in reducing health costs

(for humans, wildlife and livestock) and preventing environmental degradation.

• Relaxation of Default Action Levels (DALs)

The most important policy change for decreasing pesticide use is a relaxation of the default action levels (DAL) of the Federal Food and Drug Administration. Default action levels describe the maximum amount of insects and microorganisms which can be present in produce and the current trend has been a decrease in the acceptable number. Originally these levels were established because of the actual risk of disease transmission and the perceived demand of American consumers to purchase "undamaged" produce. In some cases, the actual health risk is quite small. In order to have cosmetically appealing food more pesticides must be used that can increase the amount of pesticide residue found on the produce. Consumers aren't aware of the amount of residue on food which they purchase, and are forced to choice produce based solely on its appearance. If they were more aware of the health risks of pesticide residues and the actual levels of residue on their produce, they might actually choose less cosmetically appealing produce in favor of healthier more natural produce. Reducing the DAL's when the associated health risks aren't very high and providing consumers with residue information can reduce the amount of pesticide use (see also section 7.2.1; Food Safety).

Other nations and provinces including Sweden, Denmark, The Netherlands and Ontario, Canada, have legislated programs which will reduce pesticide use by 50% in the next few years. The farmers of the Upper Valley and of New Hampshire and Vermont have the opportunity to join the leaders of the movement towards a more sustainable future.

5.4 FERTILIZERS

5.4.1 Introduction

A fertilizer is a substance which is used to provide one or more nutrient elements needed by plants as well as organic matter needed for soil structure. (43) It may be either a naturally occurring or an industrially manufactured product. In both cases the nutrient elements are alike and have the same effect on plant growth. (44). When nutrient supply in the soil is insufficient for crop needs, additional nutrients in the form of fertilizers can make up the difference. Some of the basic nutrients fertilizers can supply are the following: Macronutrients; N, P, K, S, Mg, Ca, Micronutrients; Cl, Fe, Mn, Zn, Cu, B, Mo.(45) Besides nutrients, fertilizers in the form of manure can also add structure and organic matter to soil. There are several alternatives to chemical fertilizers in the form of manure, green manure, sewage sludge, compost and human waste. Each of these alternatives provides varying amounts of nutrients and organic matter to the soil.

5.4.2 Fertilizer Trends in the U.S.

Yield level obtained without any fertilizer is on the order of 25 to 45 % of the optimum yield under current (1990) agriculture (what natural fertility can support). (46) Removal of N, P, and K is 15-35, 5-15, and 10-25 kg/ha, annually. Without fertilizer inputs to supply the nutrients harvested from agriculture, production would decrease. (47) National chemical fertilizer consumption in terms of nutrients (metric tons) is on the order of 220,000 of nitrogen, 140, 000 of P2O5, 82,000 of K2O. (48) In recent years, chemical fertilizer use has increased on a national and global scale with increased erosion and cultivation of marginal lands requiring heavy fertilizer inputs. (49) The sustainability of commercial fertilizer depends on the amount of reserve of the raw material and the energy to manufacture it. Sustainability of P and K fertilizer depends upon reserves of rock phosphate and KCl deposits. Rock phosphate is projected to last 650 years if use continues at the 1981 rate. (50) Using the US Bureau of Mines and Geological Survey data with an estimated 3.6% annual increase then the reserves would only last 88 years. If K reserves are depleted by 1974 rates then it could last for 3,640 years but only 107 years if the annual growth rate is 5%.(51)

Chemical fertilizer production accounts for 40-60% of the energy use in agriculture. (52) The resource most unsustainable in the production and use of fertilizers is the use of fossil fuels for traction since these reserves are most likely to become scarce. (53) The micronutrients used for fertilizer may not be exhausted any time soon but their active mining can contribute to the loss of fossil fuel reserves. Looking much further ahead into the future (>200 years), these natural mineral deposits can feasibly become exhausted. The energy consumed to produce commercial N fertilizer is 18,000 kcal/kg of N. (54) Energy required for production of N fertilizer is much greater than for P and K. P requires 3,000 kcal/kg of P and K requires 2,300 kcal/kg of K. (55)

Chemical or mineral fertilizers in general are high input processes generally requiring some raw material from which to extract the compounds needed, i.e. phosphate fertilizers are manufactured first by extracting rock phosphate and then chemically treating this form of phosphate to produce the fertilizer. (56) "A new factory for complex fertilizer with N, P, K (like the ones most commonly used in conventional farming practices in the US today) starting from natural gas may make about 2500t/d of product and cost some USD 600 million to build." (57) Therefore the future of chemical fertilizer use is not sustainable by our ecological definition because a great deal of fossil fuels must be used and the inputs from outside the region are very high. Alternatives to this type of nutrient input must be considered for sustainability to be achieved.

Synthetic fertilizers have several negative impacts on the environment that make it unsustainable to use in agriculture based on our ecological and general definition of sustainability. Synthetic fertilizers require large inputs of fossil fuels for their manufacturing process as well as for the transportation of these materials to farms far away. Since fossil fuels are scarce and will eventually be depleted it is unsustainable to rely solely on its use. Another related problem of fossil fuel use is the production of CO2 which can contribute to global warming and can thereby have a negative impact on everyone’s environment. Mining of raw materials for production of N, P, K chemical fertilizers is also unsustainable because it requires a dependence on a finite resource which is being rapidly depleted by current agricultural practices. Application of synthetic fertilizer to soils year after year can seriously harm soil fertility in the long run because it can lead to depletion and erosion of soil organic matter and nutrients. In order to make fertilizer use in agriculture sustainable, inputs of synthetic fertilizers must be minimized and alternatives to this type of fertilizer should be considered.

5.4.3 Fertilizers in the Upper Valley

In the Upper Valley region, chemical fertilizer is applied on an average of 51% of all farms. (58) Farms in the Upper Valley generally supplement their chemical fertilizer use with animal manure (Rendell Tullar). There is a sentiment among farmers in this region that chemical fertilizer inputs are costly, more so than animal manure and so they attempt to minimize these inputs with manure, preferably from their own livestock (i.e. dairy cows). (59)

Another management technique used by local farmers is close monitoring of their soil’s fertility or more specifically, available soil nitrogen content, so as to avoid over-application of chemical fertilizers. (60) But according to Nick Comerci, the challenge to providing these monitoring services is the sheer lack of man power and financial resources available to local government agencies (61).

One of the greatest challenges to Upper Valley farmers, especially vegetable or non-livestock farms, is finding a cheap and abundant source of animal waste or other natural nutrient source to supplement their chemical fertilizer use or even replace it altogether with a nearby source. (62) One solution to help alleviate this problem may be to recommend that farmers have some livestock such as pigs, chickens or even a cow to produce manure on their farms. On the other hand, keeping livestock, especially cows, requires land to grow feed for these livestock and veterinary costs to maintain the animals. Small farmers in particular may be limited in keeping livestock because the returns with respect to manure may not offset the costs of growing their feed on site (without expending more money to import feed which is unsustainable). Maybe the solution is integrating or diversifying farms with the introduction of livestock with minimal dietary and spacial needs. Pigs may be a particularly good animals to keep because its diet is so flexible. You can feed it wastes from the home or the farm and it doesn’t need land to graze like a cow so its upkeep is minimal and its production of manure may be useful.

With less farms and increasing size of the average farm, more and more nutrients are needed of the manure type to maintain soil organic matter as well as soil structure and nutrient supply. Farmers must compensate for the increased loss of soil and nutrients from erosion and intensive farming practices. Therefore the biggest challenge to farmers in this region is ultimately finding a cheap, accessible and environmentally "friendly" nutrient input that can close the nutrient cycling loop in the Upper Valley.

One way that the Upper Valley can attempt to minimize inputs while still maintaining their small farms sustainably is possibly promoting an alternative type of agriculture such as organic farming. Several organic farms already exist in the Upper Valley and is on the rise (Refer to Section 6.3.2). In particular, organic farming promotes minimal inputs of chemical or synthetic fertilizers (as well as pesticides), promotes close monitoring of crops, and can generally (although not always the case, see section 7.2.1) be considered in line with our definition of ecological sustainability. Whether or not the move towards organic farming in the region is sparked by financial or ecological incentives, the fact remains that it is a step in the right direction and it reflects an overall sentiment of environmental awareness in the region.

5.4.4 Fertilizer Application

Application timing is crucial for avoiding reduced crop yields from too little application and avoiding environmental damage due to over-application. Local knowledge of the soil and previous crops are essential to planning the application. Fertilizer application technology is an area in which farmers have an opportunity to reduce the over-application of nutrients with a combination of more precise machinery (that is machinery that is lightweight and can apply the fertilizer to very precise areas of the field) and a comprehensive understanding of the soil’s fertilizer needs.

The challenge for farmers specifically in the Upper Valley is that new technology such as precise applicators of fertilizer is expensive so many small farmers in the region can not afford such an investment. Also, if the trend for increased farm size continues and small farms die off, then it becomes more difficult and costly to monitor soil nutrient needs and retain that close monitoring and knowledge which small farmers can achieve. Ultimately, the goal of fertilizer application should be to minimize all kinds of fertilizers, so as to reduce the dependency of Upper Valley farms on outside resources, making fertilizer use more sustainable.

5.4.5 Local Alternatives to Synthetic Fertilizers

• Manure

Organic manure can be both from animal and plant origins but usually comes from dung and urine of farm animals. "Manure is a good alternative to chemical fertilizers because it releases nutrients to the crop slowly over the growing season." (63) This type of fertilizer can also act as an agent for improving soil structure and increasing humus content. But it requires either keeping enough of your own livestock to produce fertilizer for your crops or purchasing it from an outside source. When small farmers can not afford to keep their own livestock because they don’t have enough land to grow the necessary feed for their livestock then they may be limited by how much manure is available locally as a cheap source of nutrient input. So the bottom line is really land availability. Do we have sufficient land to support enough livestock to then fertilize fields? The Upper Valley may not have enough land indeed, but if livestock with minimal space requirements and flexible diets were used instead of cows, which require a lot of land and feed, then integration of livestock may be sustainable in the Upper Valley (Refer to Chapter 4, Land Preservation). In order to close the nutrient cycling loops, livestock, fertilizer (manure), and crops to feed humans and livestock must be considered in the context of the Upper Valley land limitations.

Manure application, storage and handling requires a great deal of input of labor and special equipment. Thus the transportation of manure from far off can be unsustainable from both an economic and environmental standpoint. New drying processes for manure may prove useful for this problem but may also reduce the usefulness of manure as a soil structure and nutrient additive. (64) Another challenge of manure is that nitrogen is easily lost from stored manure in the system therefore it has to be collected quickly and properly stored and applied before NH3 volatilization occurs. (65) Manure can be stored either as a liquid in aboveground tanks or in an earthen lagoon. The earthen lagoons carry the potential for runoff or leaching and above ground tanks, besides being very costly to acquire and maintain, can also leach nutrients from below. (66)

Another problem associated with storing manure is having nutrients leach from storage facilities to water systems nearby. To avoid leaching nutrients, manure should be applied at the same rate as the rate of uptake by the crop. (67) One way to accomplish this is by applying fertilizer several times during the growing season rather than applying all of it before the planting. (68) Once nutrients from fertilizers such as nitrogen or phosphorus, runoff the fields or from storage facilities and into marine or fresh waters, the results can be detrimental.

Composting manure is a technique sometimes used to stabilize manure prior to application. It reduces odor and improves physical composition so as to make handling of manure easier. (69) This technique usually consists of a pile of alternating layers of soil with organic materials such as manure. Sometimes these compost piles are turned or mixed and after several weeks are ready to be spread on fields. The disadvantage of composting is the loss of N and availability of N in remaining manure. Pratt and Castellanos found that N availability in composted dairy manure was only half of that in fresh manure. Injection of liquid manure reduces ammonia loss and increases potential for denitrification but again, farmers in the Upper Valley generally do not have access to this type of technology. (71) Efficiency of nutrient use can be improved by applying manure as close to planting as possible. Fall application of manure for spring planted crops results in significant nutrient loss from the cycle due to volatilization and leaching of nutrients. (71) Another problem with composting is that it has higher demands for labor relative to the amount of nutrients available to plants. (72)

• Green Manure

Fresh plant material that is added directly to the soil without passing through animals or composting is green manure. This type of fertilizer helps prevent erosion and conserves nutrients but doesn't add nutrients like manure does. Sometimes it is used in autumn to take up nitrate that would be lost from the system but some lands are not able to handle this because they are not arable in the fall such is the case generally in the Upper Valley.

• Sewage Sludge

Sewage sludge is another alternative to chemical fertilizers. The basic treatment process for sludge is the following: thickening, stabilization, conditioning, dewatering and drying, thermal reduction, and composting. (73) Most sludge used for farm land are anaerobically digested and thermally reduced before application occurs to treat the waste for pathogens and parasites that may be in the sludge. (74) Although there are no reported incidents of human diseases due to sludge in soils, the USDA contends that continued epidemiological studies are needed to further assess the risk of human pathogens and parasites. Techniques such as sterilization, pasteurization, radiation and heat drying, and composting can eliminate pathogens and parasites from waste as well but the degree to which it removes these and the public’s acceptance of it are still uncertain. (75)

It takes about 50,000 people in a community to produce the equivalent of 5 tons of dried, anaerobically digested sewage sludge per day (could fertilize in a year 100 to 200 ha of land). (76) But the quality and usefulness of sewage sludge varies based on its source and treatment system. Most of the nutrients in sewage sludge are only partly available to crops in the first growing season since about 70% of the N and P is in the organic form and thus not available to the crop. (77) One concern regarding the use of sludge is the odor which can be avoided by proper digestion of the sludge or immediate incorporation of the material into the soil. (78) The biggest concern regarding sludge is its excessive content of heavy metals such as zinc, nickel and cadmium which can accumulate to toxic levels in the soil. This type of contamination derives mainly from inclusion of industrial waste into sewage sludge. Without this industrial component, sludge’s heavy metal content could be significantly reduced and sludge could become a more viable option as an alternative nutrient source for local farmers. (79) This is where septic systems can also be utilized. Septic waste has the potential to be relatively heavy metal-free because each individual home is responsible for eliminating possible contaminants from their residential waste. Therefore septic waste could be a source of relatively benign sludge. Sludge could be a key player in closing the nutrient cycling loop in a farming region since it has the potential to provide a cheap, abundant, and local source of nutrients.

• Composting

"Composting is the aerobic decomposition of organic materials by microorganisms under controlled conditions which produces a soil-like substance called humus." (80) Although compost is not usually thought of as a fertilizer due to its low nutrient levels compared to that of manure’s, it can still be used as a valuable subsidy to manure fertilizers and even small soil amendments can be accomplished using composted materials.(81)

Two studies in New Hampshire set out to examine the feasibility of recovering food waste from various local sources (i.e. school cafeteria, restaurants, lawn wastes, etc.). Using on-farm composting, the farmer can make money from a tipping fee (which would normally go into dumping waste in a landfill) and then either use the compost on their crops or sell it as a commodity (loam production, land reclamation, other farms needing nutrient inputs, topsoil, etc.). (82) The cost per ton for producing compost ranges between $11-$13 while tipping fees for solid waste averages about $50/ton in New Hampshire. (83) These proposals by Halstead and Cook determined that such a practice is economically feasible in New Hampshire and in the long run can help retrieve nutrients from local waste products and invest them back into local food production in the form of fertilizer (Table 5-4).

Dartmouth College's composting facility at the site of the old landfill is a step in the right direction. This facility will have three waste streams: one will be limited to college waste from dining services and landscaping, etc., the second will be for Hanover municipal waste which is sewage sludge and the third will be a research, experimental stream. This plan to compost some of the college's waste does not include on farm disposal sites so that agriculture and food production are not brought into the recycling of nutrients directly. Instead, for farmers to get the composted material they have to pay Dartmouth a fee. On farm composting sites bring the benefits of composting directly to the farmer without the intervention of a middleman such as Dartmouth. But even so, this facility can be a model for other towns in the Upper Valley to consider. The inclusion of an experimental composting stream may offer knowledge and experience that can help to encourage other towns to try such practices.

A challenge to closing the nutrient cycling loops is the importation of food from outside the Upper Valley region (See Section 7.3.2). Imported food represents an environmental cost because of its intensive consumption of fossil fuels for transportation. To close this cycling loop both fertilizer and food inputs from outside the Upper Valley must be kept to a minimum for long term sustainability.

No one single alternative to synthetic fertilizers can sufficiently meet all of the nutrient needs of Upper Valley farms. Therefore a combination of these alternative practices or an integration of some of these practices to supplement current practices must be used to make fertilizer use in the Upper Valley ecologically sustainable.

5.4.6 Policy Recommendations

The key to sustainable agriculture is minimizing inputs and promoting on--farm nutrient cycling. The largest loss from the nutrient cycle is the harvested crop. Some farmers may be able to keep livestock to supplement their nutrient needs but for many farmers in the Upper Valley, livestock is simply not feasible due to limited land availability. Traditionally, chemical fertilizers have been employed to offset nutrient losses. Other ways to supply these nutrients are animal manure, green manure, sewage sludge or composted waste. So is the Upper Valley sustainable in its use of fertilizers? When considering the fact that almost all farms in the area are still using chemical fertilizers for a great deal of their soil’s nutrient needs then it becomes evident that the answer is no. Agriculture in the Upper Valley is not yet sustainable from an ecological perspective particularly in regards to fertilizer use. But the region seems to be on the right path with a greater interest in organic farming which promotes minimal synthetic fertilizer usage. Also the consideration by towns such as Hanover to begin a composting facility also shows a step in the direction towards sustainability. But there still remain many points which could make farmers in the Upper Valley more ecologically sustainable as it pertains to fertilizers:

(Source: Halstead, J.M. et al. Composting for New Hampshire Communities.

NH Agricultural Experiment Station, University of New Hampshire. Durham,

NH, 1993. )

Table 5-4. Representative Analyses of Three Composts and One Topsoil.

(Source: Halstead, J.M. et al. Composting for New Hampshire Communities. NH Agricultural Experiment Station, University of New Hampshire. Durham, NH, 1993.)

5.5.1 Introduction

Non-point Source Pollution is defined as contaminants that enter our water resources when water washes across the surface of the land or infiltrates to groundwater. (84) Also termed "people pollution", non-point source water pollution does not come from a specific "point" of entry (such as a factory disposal pipe) but from widespread contaminants generated by the activities of our daily lives. Road salting, septic systems, timber harvesting, farming, lawn care products, chemical and petroleum storage, and urban stormwater runoff all contribute to NPS pollution when unwanted products are carried by runoff water into local rivers, lakes and streams. (85)

The agricultural component of NPS pollution comes mainly from the use of pesticides and manure/fertilizers, and from soil erosion. Pesticides (comprised of herbicides, insecticides, and rodenticides) in some cases, and especially if applied improperly, can leach into surface water and groundwater supplies. While these chemicals may infiltrate unnoticed into local water, the effects are more obvious. Certain pesticides will poison humans and wildlife if consumed through drinking water (See Section 5.3.2). Pesticides with long half lives that persist in the environment, though generally banned from use in the United States, bioaccumulate as they travel through the aquatic food chain. This harms the larger predators who experience concentrated levels of the chemicals which may alter hormone levels and inhibit reproductive capacity. (86)

Manure and fertilizers, while needed and highly beneficial inputs to agriculture, can also cause problems in aquatic systems for the very same reasons that they solve problems of soil productivity. Fertilizers provide nitrogen and phosphorus, which are the major limiting nutrients in plant growth, thereby increasing crop production. These same nutrients, however, are also the limiting nutrients to aquatic algae and weed growth. When these seemingly beneficial nutrients are washed off the land and into bodies of water, algal blooms result from the elevated nutrient levels. Besides being unattractive, this proliferation of algae reduces dissolved oxygen levels through respiration and decomposition. This in turn reduces the capacity of the system to support organisms dependent on high oxygen levels, such as fish and insects.(87)

Aside from pesticides and fertilizers, water washes soil particles themselves further down in the watershed. Erosion not only reduces land fertility by removing topsoil, but it also causes sedimentation of the water bodies and may bring further pollutants that were attached to the soil. (88)

5.5.2 NPS Pollution in the Upper Valley

Most people, including the New Hampshire Commissioner of Agriculture, (89) feel that agricultural non-point source pollution is not a significant issue in the Upper Valley. Howard Patch of Walhowden Farm feels that erosion is a problem, but not a huge one (90), and the Taylors deal with wind erosion on Crossroad Farm.(91)

Specific data on agricultural non-point source pollution into the Connecticut River is hard to come by, largely since the inherent nature of a non-point source is that it has a broad range and is consequently hard to pin down and quantify. Still, according to the New Hampshire Department of Environmental Services (NHDES) "in NH, there has not been adequate water quality monitoring or study on the extent and severity of agricultural NPS pollution". Overall non-point source pollution estimates were collected by the NHDES for the southern sub-basin region, including the Upper Valley. Land disposal (dumps, junkyards, and municipal landfills) contributed to 33% of the NPS runoff, septic system seepage comprised 27%, with "other" inputs at 23%. Farming inputs fit into this "other" category, but road salt made up the largest percentage of "other". Based on this assessment, the NHDES does not consider agricultural inputs to significantly contribute to statewide NPS pollution. (92)

5.5.3 Prevention Methods

Even though source pollution is not considered to be a large problem in the Upper Valley, it is not an issue that should be ignored. Practices as they are now appear to be sustainable, yet conservation methods are still in order, both to prevent further problems arising as farming procedures change and to relieve sub-basins of concentrated runoff.

Excellent methods to reduce agricultural runoff include those implemented in the Morris Brook Study of the Connecticut River Watch Program. The study included construction of four main structures to reduce cattle manure contamination: 1) manure storage areas to in timing of manure application to fields, reducing manure runoff; 2) concrete barnyard pads in areas of heavy use to reduce erosion; 3) gutters to divert roof runoff from high use areas; 4) a stream crossing to keep animals (and their waste) from directly contaminating the water and eroding the bank. (98) Both states have programs to encourage proper manure storage, such as concrete bunkers with drainage control (see the law/policy section for a description of these programs). (99) According to Dick Flanders of the NHDES, programs to stop the undue spreading of manure have made large improvements over the past ten years, and the increased use of rain gutters has helped to divert rainwater so that it will not capture pollutants and carry them into streams. (100)

One way to prevent pollutants from reaching the surface water and groundwater is through the use of conservation buffers. Buffers use various means to achieve a common goal. They make use of vegetation to act as a natural barrier to manure, fertilizers, pesticides, soil, and other contaminants which would otherwise be washed into nearby bodies of water. Through the use of a well planted buffer area between cultivated land and nearby water, it is possible to trap most agriculturally derived NPS pollutants. Various types of conservation buffers may be employed for this purpose. (101)

• Riparian buffers/Streambank plantings

The planting of endemic or exotic vegetation (trees, shrubs, and grasses) alongside streams or other bodies of water. Can be as simple as allowing native vegetation to grow alongside the bank. Serve to intercept runoff contaminants.

• Filter strips

A less elaborate form of streambank planting, filter strips are merely a strip of grass along the edge of a body of water.

• Contour grass strips/Vegetative barriers

Slender strips of perennial vegetation such as grass, when alternated between crop strips perpendicular to the slope of the land (contour cropping), serve to reduce erosion and contaminant flow.

• Grassed waterways

In areas where water from fields runs into streams, the use of grass in the waterway prevents the movement of soil, nutrients, chemicals, and pathogens along with the water.

• Wellhead protection areas

Buffers of vegetation surrounding a well serve to protect these important human water sources from contamination.

Conservation buffers are not used much in the Upper Valley, although sod runways surround most farms, and farmers usually do not cultivate steep slopes, especially by streams. (102) The benefits from properly designed and maintained conservation buffers are significant. The main reason conservation buffers are not of utmost priority in the Upper Valley is because the vegetation is trapped in a less-than-helpful frozen form for much of the year, due to the cold climate. (103)

Unfortunately, many farmers cut down the trees by streams. While this prevents shading of crops, it also keeps shade from the stream, opening it to the sun’s rays and thereby increasing the diel variance in temperature and increasing the overall temperature. (104) These harsh conditions reduce the diversity of aquatic life (fish and aquatic invertebrates) in the streams.

Buffers are capable of removing approximately 50% of pesticides and nutrients, 60% of microorganisms, and 75% of the sediment which would otherwise run off into nearby bodies of water. (105) Besides reducing NPS inputs, buffers can provide shelter and pathways for many terrestrial animal species, and overhanging vegetation prevents extreme fluctuations in water temperature. Without NPS pollutants, the water chemistry in nearby streams becomes much more stable, allowing for a wider diversity of aquatic life. (106)

The USDA has instituted the Conservation Reserve Program (CRP) to encourage the formation of conservation buffers. The goal of the program is to "establish 2 million miles of conservation buffers by the year 2002". (107) Through the program, most buffers earn a 20% incentive, and up to 50% of the cost to establish the buffer is paid by the program.(108)

Ideally, the rest of the establishment costs could be paid by organizations in the Upper Valley. Either the state government or local NGO’s could contribute to the implementation of conservation buffer use. There is no good reason why the Upper Valley can’t benefit from the use of this program. Combined with proper pesticide use and improved manure storage, these methods will ensure that the treasured clean water of New Hampshire remains clear of NPS pollution problems.

5.6 BIODIVERSITY

5.6.1 Introduction

Agriculture as it is practiced today can both limit and expand the biodiversity of the system. Because farmers generally plant fields in monocultures, attempt to keep pest species off of their land, and control the breeding of their livestock, the biodiversity of an agroecosystem is inherently limited. However, on a larger scale, moderate agriculture can increase the biodiversity of a region by creating different habitats. If agriculture becomes the dominant land use in the area, the regional biodiversity will be limited to that of the agroecosystem.

5.6.2 Scales of Biodiversity

Biodiversity is not simply the number of species present in an ecosystem, but is defined differently on different scales. On the smallest scale is genetic diversity, or diversity of the gene pool within a community of organisms of the same species. The next level brings in species diversity, or the number of different species present in a given area. Species diversity itself has several scales. Ecosystem diversity also encompasses the structural and functional diversity of the ecosystem. (110) This means that having species occupy different niches and performing different services in the ecosystem make it more diverse.

The different scales of biodiversity are an integral part of the health of an ecosystem because they describe the interactions between the species. If one species is dominant, the biodiversity is low and the system is more susceptible if a catastrophic disturbance occurs affecting that particular species. The species present in a given system are a function of its diversity, which thus controls all the interactions occurring in that system. Managing for overall biodiversity entails managing the system as a whole, not just the crops, pests, soil, and livestock. Herbivores, weeds, insects (pests, predators, and pollinators alike), native and introduced species must all be considered part of the biodiversity of an agricultural ecosystem.

5.6.3 Genetic Diversity

Genetic diversity includes the "degree and variability of genetic information in the system (within each species and among different species.)" (111) It provides the basic genetic material for all present and future crop and livestock species. New, more resistant or more productive crop strains can only be created by manipulating natural genetic material. Thus, it is important for this genetic material to be preserved, and even allowed to evolve, in order for additional strains to be synthesized.

Over time, small populations tend to lose genetic diversity unless it is replaced by mutations, which are also more infrequent in smaller populations. Inbreeding, or mating between related individuals, is also more likely to occur in small, isolated populations (such as herds of livestock). Because farmers can control the breeding of their animals, they can ensure that their livestock does not become inbred, but they must have the information and know how to do so. Farming selects organisms for certain beneficial traits, limiting the gene pools of many farm animals and crop species over time. These reduced gene pools can lead to problems in the future. As the gene pool gets smaller, deleterious recessive genes are more likely to be expressed, and the population can become weak. Also, a smaller gene pool means that the population has less phenotypic diversity, which makes it more vulnerable to extinction. (112)

Aggressive breeding practices to select for particular traits could also jeopardize the genetic diversity of species so as to reduce their ability to evolve. Without a significant amount of phenotypic diversity, populations cannot evolve over time.

5.6.4 Species and Ecological Diversity

Species diversity is "the number of different species in the system" and their relative abundance. (113) Numerical indicators of species diversity generally take both of these into account.

Ecological diversity encompasses several levels. It includes not only the number of species within an ecosystem, but also the spatial, functional, and temporal diversity of the organisms. In the context of farm ecology one must consider that having species with a variety of different characteristics and which fill different niches in the ecosystem increases the overall biodiversity. For example, a farm ecosystem with 10 different species, 8 of which are varieties of grain, is not as diverse as an ecosystem with 10 species of various plants and animals. Ecological diversity incorporates these factors.

5.6.5 Importance of Biodiversity

In general, "greater species diversity leads to greater differentiation of habitats and greater productivity, which in turn allow even greater species diversity." (114) Also, increased diversity generally makes an ecosystem more resistant to disturbance and able to recover more quickly from the disturbance it does sustain. It is important to note that the disturbance regime in an agricultural ecosystem is generally controlled by humans to be more frequent and intense than in most natural ecosystems. Thus, biodiversity in an agricultural ecosystem can be especially important to maintain the health of the agroecosystem over time.

Biodiversity has been declared an international conservation priority through the United Nations conference at Rio de Janeiro in 1992. (115) Nations around the world have recognized that biodiversity should be preserved both as a resource and as a part of nature itself. In the United States, the Endangered Species Act promotes species biodiversity by protecting species and populations deemed to be at significant risk of extinction.

Biodiversity in general is important for the genetic concerns mentioned above, new medicines or industrial agents derived from biological substances, and the aesthetic/spiritual value humans derive from healthy natural ecosystems. (116) Biodiversity in agroecosystems provides a variety of services to the system, especially for pest management, including:

Plants & animals in agroecosystems, as in natural ecosystems, can also control the flow and filtration of water, sediments, and pollutants. They break down soil organic matter into components useful for crops and help prevent leaching of nutrients and erosion of soil from the system. However, because farm ecosystems are highly managed, biodiversity on a farm and the services it provides must be considered different from those in natural ecosystems. The populations in agroecosystems may be limited by farming practices so that they cannot perform these functions. For example, if a manager uses herbicides on a field so that only the harvested crop can grow and does not grow another species between harvesting and the next planting, soil and nutrients would be able to leave the system more easily.

5.6.6 Protecting Biodiversity

In general, increasing the biodiversity of an agroecosystem entails adding more complexity. Adding plant species which have different structures not only adds directly to the number of species, but can also provide a more diverse habitat for additional organisms to enter the system. Targeting pesticide use to a particular species can allow more insect species to inhabit the area.

Methods to increase the biodiversity of an agricultural ecosystem include: intercropping and polycultures (growing more than one crop in the same field), hedgerows or buffer vegetation, planting a non-crop species between crops, rotating crop species, fallows, minimizing tillage to retain soil organic material, adding materials high in organic matter, and minimizing the use of chemical inputs. (118)

5.6.7 Biodiversity in the Upper Valley

In the Upper Valley, biodiversity is not as great a concern as it is in farming communities where vast tracts of land are devoted to the same crop, with little or no space devoted to other uses. Farmland only covers approximately 12% of the land in the Upper Valley, thus it is not inherently jeopardizing biodiversity by dominating the landscape. (119) The smaller scale of farming in the Upper Valley increases biodiversity by providing alternate habitats for different organisms. However, the smaller the scale, the greater the biodiversity because more habitats will be present in a given area. Thus, smaller farms and fields tend to increase beta biodiversity. It would be impractical to legislate or enforce the creation of only small farms in the Upper Valley, however it is important to be aware that smaller farms surrounded by other land uses do tend to benefit the biodiversity of the region.

The genetic diversity of some crops and livestock in the Upper Valley may be at risk. According to Steve Taylor, New Hampshire Commissioner of Agriculture, only about 30 families of Holstein cows remain. This means that the overall genetic pool is very small. As the genetic pool gets smaller, inbreeding effects (such as weak legs) become more prominent in the population, even though farmers don’t actually inbreed the animals because recessive genes can become more frequent. These families are often crossbred and some breeders are importing genetic material from Holland to keep their populations viable. (120)

The national Holstein Association and the USDA keep track of the inbreeding coefficients of all Holstein cows and the expected inbreeding of their progeny to ensure that the breed as a whole is not being inbred. Right now, the level of inbreeding is at about 3.5% out of 100%. (121) Even though the actual amount of inbreeding is quite low, if the gene pool is very small, negative inbreeding effects may occur. The breed association is helping farmers keep track of deleterious recessive genes, but inbreeding effects other than the expression of these genes may occur if the gene pool becomes depleted. Also, the genetic material being imported from overseas is actually coming from the offspring of bulls sent to Europe over the last 20 years, so this practice does not significantly widen the gene pool. Because European countries are using the American genes to breed their animals, the gene pool may be shrinking worldwide, making it difficult to bring in more genetic material if future problems arise. Holsteins could always be crossbred with other breeds, but this would probably be a last resort. (122)

Taylor also commented that some plant strains may be at risk because of a lack of genetic diversity, but that the USDA and state university systems are working to maintain the seed stocks of crop plants. This will be important to the creation of new strains. However, simply storing the seeds of diverse plant strains will not allow them to evolve. Thus, they may need to be planted in fields in order to allow beneficial evolution to continue. About 15 different companies have several

varieties each of corn, alfalfa, and clover, the major crop plants, providing some degree of genetic diversity for these species. (123)

Fertile soil in the Upper Valley has about 1 billion microbes per gram, which is considered normal. The diversity of these biota can be preserved by maintaining the soil pH and adding diverse organic matter. Soil microbes grow especially well in warm, moist soil that has been fertilized with manure. In general, the soil conditions that are best for crops are also ideal for soil microbes. (124)

Crop rotation on corn fields also preserves biodiversity. Farmers often grow corn on a given field for several years, and then rotate it with grass or alfalfa for several years. Rotation increases biodiversity via the same mechanism as cover crops, but over a longer time scale. It does not protect the soil nutrients as well, however, unless other practices are utilized between harvesting and replanting.

5.6.8 Conclusion

The most immediate concern relative to the biodiversity of the Upper Valley agroecosystem is that of genetic diversity. The diversity of dairy cows is especially at risk. Farmers may have successful dealt with the paucity of genes in their herds for the time being, but if future problems arise there may not be a larger worldwide gene pool for local farmers to draw upon to expand their herds. (129) Thus, farmers should take steps now to expand the gene pool of their herds to prevent future difficulties.

From the available research, it is impossible to determine the exact state of the overall biodiversity of the system - whether it is steady, increasing, or decreasing. The fact that farms create many different habitats, as well as edges along habitats which favor different organisms, adds to the overall biodiversity of the system. Since the land being farmed in the Upper Valley has been farmland for many decades, biodiversity is currently not being threatened by the clearing of new land for farms. However, too much of the same land use in a region is detrimental to biodiversity. If more land were to be dedicated to farming, the balance between farm ecosystems and other natural areas might be disrupted, and biodiversity could decrease.

Development may be a greater threat to biodiversity than farms because it reduces the amount of habitat even more than farming. Methods such as cover cropping and buffers can be further implemented to protect the soil and water of the ecosystem while maintaining or increasing the biodiversity, and therefore the sustainability, of the system as a whole. From the standpoint of biodiversity, ecologically sound farming is generally more beneficial than developing the land. Policies to protect current farmland from development will serve to protect the sustainability of the biodiversity of the system.

In order to provide enough food to feed the growing global population, sustainable management of natural resources can be a challenging feat. Economic, cultural or societal values, and environmental factors all play a role in the use of our natural resources. In the Upper Valley, the same factors apply. However, there are several practices which can aid farmers in coming closer to ecological sustainability.

Is agriculture sustainable in the Upper Valley based on our ecological definition? To adequately answer this question there are certain criteria mentioned in the introduction and detailed in each section that farms would have to meet in order to be considered sustainable such as:

After evaluating these criteria along with the original definition of sustainability in our introduction one would have to conclude that agriculture in the Upper Valley is not yet sustainable from the ecological perspective. There is much work to be done before achieving these criteria. The following recommendations are aimed at achieving ecological sustainability or atleast getting the Upper Valley started in this direction.

• Farmers in the area should continue to be encouraged to engage in contour plowing,

conservation tillage and a system of no—tillage .

Each of these practices will help to minimize soil erosion and increase biodiversity in the region. In addition, sustainable agriculture requires the inputs of fewer unnatural products into the system. Thus, subsidies to use natural predators as biological control agents could be implemented by perhaps having local universities research them and then industry incentives may be developed to provide these techniques at a low-cost to farmers.

• Relaxation of the Federal Food and Drug Administration’s default action levels (DAL).

These levels which have set the maximum amount of insects and microorganisms allowed in produce have been decreasing recently. It is possible that the decrease in allowable amounts of insects and microorganisms is more a reflection of aesthetic taste than real health risk to the consumers. In this case, it may be beneficial to inform consumers that less aesthetically attractive produce have been treated with less chemical pesticide inputs relative to produce that seem more cosmetically "perfect" and are equally free of health hazards. This association of "perfect" produce with pesticide use may encourage farmers to use less pesticides since seemingly less than perfect products can still get a return without heavy inputs of pesticides.

• Encourage more conservation buffers on farms, especially those located along the river .

This could help to conserve soil, salvage marginal lands, increase biodiversity, and reduce water pollution caused by pesticides and fertilizers. As mentioned several times earlier, the conservation buffer system would pay farmers a certain percentage of what money would normally be earned on the land if it were in production. The percentage that is not paid by this conservation program should be subsidized by the local and state agencies so that the farmer can get 100% of the value of their land as incentive to implement the plan.

The bottom line is this: conservation buffers are valuable considerations on all aspects of the ecological front, from erosion control to havens for wildlife. However, buffers are not yet completely economically feasible for many farmers. The returns for buffered lands are rarely 100% equivalent to the revenue farmers would be earning if they were to cultivate the land. The idea behind buffers revolves around the non-monetary gains of conservation, the long-term benefits of farming with buffers.

• Explore options to implement a pilot project involving the use of human waste from sewage or

septic systems.

This alternative might involve obtaining federal or state grant money to implement such a project starting out on a small community scale. This plan would first eliminate industrial products from the main sewage system to avoid problems of heavy metal contamination. In the case of septic systems, take the waste directly from the septic tanks and test them for any contamination from heavy metals, using the best available technology, the human sludge could be treated, composted and monitored for sludge quality to reduce any risk of soil or crop contamination. The use of sewage could divert dollars away from the cost of disposal of the waste and make sewage a useful commodity.

Manure and composting supply less than 50% of the fertilizing materials used on Upper Valley farms. (130) Since our definition of sustainability attempts to reduce the consumption of fossil fuels and the use of synthetic materials, Upper Valley farms can only be sustainable when they find alternatives to synthetic or fossil fuel intensive inputs. Also fossil fuel intensive practices and inputs, besides being detrimental to the global environment can become ecologically unsustainable when fossil fuels are depleted and the price of transporting these materials skyrockets. Considering these limitations of external inputs, part of the solution to cycling nutrients must involve fertilizers that are locally available and abundant. Sewage or septic sludge may offer part of the solution to the challenges facing the complete cycling of nutrients in the Upper Valley.

• Promote integration of some livestock on farms.

To complete the cycling of nutrients in the Upper Valley, integration of livestock, food and fertilizers must be considered. Integrating livestock onto farms would provide a source of fertilizer and food for farmers but would require sufficient land to grow feed to sustain these animals (with no importation of feed--unsustainable). Thus, farmers in the Upper Valley are limited by the amount of land they have to sustain livestock. Part of the solution may be to keep a certain amount of low maintenance livestock such as pigs, whose diets are very flexible and whose requirements for space are minimal (fish farms, chickens, etc. can serve this same purpose). Such livestock could supplement fertilizer needs as well as some dietary needs (by using the pig or fish, etc. for human consumption) and thus get closer to closing the nutrient cycling loop.

• Use Hanover’s compost facility as a model for similar facilities in the Upper Valley. Composting waste materials at on-farm sites is another proposal which would attempt to cycle nutrients in the Upper Valley ecosystem. Although Dartmouth’s facility does not directly involve the use of on farm sites, it may be a step in the right direction. Since the facility includes a research component that may encourage innovations for future facilities Dartmouth’s composting facility sets a precedent for the Upper Valley. Collecting food waste, lawn clippings, etc. and then paying local farmers to dump the material in a compost pile for a fraction of the cost of dumping it into a landfill or incinerator would benefit both the farmers and the local communities. Farmers could use the composted material to subsidize the nutrient needs of their crops or sell the compost as topsoil, loam, etc. The fee to tip the waste into a farm compost would be so much lower than that for landfills or incinerators that it would be a cost incentive for dumping companies and residents would have to pay less to get rid of the material.

• Increase availability and decrease the cost of soil testing and other soil or nutrient monitoring

services to the farmer.

This policy idea suggests that farmers receive more annual comprehensive testing or evaluations of their farm’s ecological health from agricultural services. The extension agencies would be responsible for promoting them within the agricultural community as a vehicle for farmers to keep updated on the health and functioning of their farm. In this way farmers in the Upper Valley could consider the implications of their practices on the various aspects of their farm and the environment. However, until more experts and funding are available to test soil, water and nutrients, the challenge becomes finding the human resources as well as the financial resources to implement this and many other programs to promote ecological sustainability.

Sustainability of agriculture in the Upper Valley has not yet been achieved but the region is headed in the right direction. The increased interest in organic farming which promotes some of the criteria for ecological sustainability and composting facilities such as Dartmouth’s, all point to a more sustainable future. The Upper Valley has a unique opportunity to close many of the nutrient cycling loops because the region is comprised of small communities that can easily transfer knowledge, information, and innovations. The down side to being so small may be the inability to be completely self sustaining year round with limited resources (i.e. land). Despite the many challenges facing ecological sustainability in the Upper Valley, a commitment to ecologically sustainable practices and innovations on farms and by entire communities can start the journey to a more sustainable future.

Ultimately farmers in the Upper Valley and elsewhere in the world are faced with trying to attain a tight cycling of nutrients, balanced inputs and outputs, within the agroecosystem. The nature of agriculture and harvesting involves the removal of vital nutrients and resources from the natural environment. But without the proper maintenance and even improvement of soil and water resources the agricultural system that is supported by these resources will suffer as will the humans who depend upon both of these systems for survival.