Farming has enabled human populations to dominate the world’s landscapes for many thousands of years. The science of agriculture has been refined and perfected over time to accommodate for the ever-increasing human population. Until recent centuries, productive crops were mostly organic and existed with some permanence as part of a landscape. As communities grow though, less and less land is available for food production and existing crops become easily exhausted. Food insecurity caused by rapid population growth has pressured science to step in and produce many synthetic chemicals and gene manipulation techniques to maximize the potential of plants. In addition, agricultural production has increased tremendously worldwide over the last century. Coupled with this growth however is the pollution and degradation of the natural environment. Many agricultural techniques exist today, but in an effort to adjust to the exponential trends of our population without compromising the integrity of the environment it is necessary to have a global transition towards sustainable farming. With the current population at seven billion and rising, an important question must be addressed: What is the most sustainable and cost effective way to feed the world’s population? Fortunately humans have been perfecting agricultural methods for thousands of years, which can help to answer this question.
This paper will analyze and compare two types of farming, organic and conventional. In a comparison of agriculture, my goal is to assess the impact and performance of each practice and then identify the best method for growing crops. Although there are many types of agricultural practices, they can be generalized as sustainable or conventional based on the techniques used. Sustainable / organic farming aims to produce a number of crops, without the use of synthetic chemicals or fertilizers, while enhancing soil composition and promoting biodiversity. This is a traditional, more permanent type of farming that relies on ecosystem services to maintain the integrity of the landscape while still producing sufficient yields. Conventional farming uses synthetic chemicals and fertilizers to maximize the yield of a particular crop or set of crops, which are typically genetically modified. This method requires a significant amount of chemical and energy input and weakens the ecology of a landscape. In a comparative analysis of these two techniques, it is important to highlight the fact that the crops studied differed in soil composition, geography, and rotation systems. “To carry on extensive long-term trials for a number of crops in several different geographical areas would be of fundamental importance to understand the potential of organic farming as well as to improve farming techniques in general.” (Gomiero, Pimentel, and Paoletti 2011). Due to the many different factors determining crop health and productivity, there is a need for much more extensive research on the subject. Therefore, my goal in writing this paper was to use reliable, long-term research that made specific assessments of the two generalized types of farming and then compare the results.
II. History of Agriculture
Agriculture has played a tremendous role in the advancement of human society. Agriculture has been around since roughly 10,000 B.C.E. and has enabled humans to manipulate ecosystems and maximize population growth (Xtimeline.com). The science has encouraged people to live and develop rich, permanent settlements all over the world. When humans first discovered the potential of planting seeds, they suddenly had the ability to explore the world and establish infrastructures wherever soils were fertile.
Soon after the start of agriculture people began to select for genes that maximized plant yields. Selective breeding was first implemented on plants over 10,000 years ago to produce desired characteristics in crops (USDA.gov). This discovery further contributed to the permanence and size of settlements. With breakthroughs in agriculture, populations increased and development spread.
Early farming techniques depended on local climate conditions, but most farmers would continue to plant on the same field year-after-year until the soils were exhausted of nutrients. This encouraged ingenuities such as crop rotation and intercropping (Economywatch.com). Intercropping is a technique in which a variety of crops are grown together, creating a microclimate that favors the survival of each plant, maximizes potential yields and maintains soil fertility (Archaeology.about.com). For example, Native Americans developed an intercropping technique over 5,000 years ago called the three sisters, where maize, beans, and squash were grown together (Archaeology.about.com). Maize consumes a lot of nitrogen, while beans supply nitrogen to the soil, and squash benefits from a shady, moist climate. Intercropping is one of many early discoveries in agriculture still being implemented today that promotes biodiversity, maintains soil composition, and fortifies plant health.
Techniques such as irrigation, intercropping, and crop rotation have progressively increased efficiency in agriculture. Over the last few centuries however, radical changes have been made in farming and many countries have made a shift toward conventional methods. Factors such as growing populations, economic instability, climate change, and pressures from companies to produce higher yields have contributed to this shift. However, adopting these conventional methods subjects farmers to the greed of industry, as their crops depend on a high input of energy, synthetic chemicals, and genetically modified organisms. And once committed to the conventional practices, farmers find themselves locked in a perpetual cycle of loans, subsidies, and debt.
III. Conventional Agriculture
Conventional agriculture is a broad term that has a number of definitions, but a crop can be classified as conventional if synthetic chemicals are used to maintain the plants. A significant amount of chemical and energy input is required in conventional agriculture to produce the highest possible yield of crops. “This method usually alters the natural environment, deteriorates soil quality, and eliminates biodiversity.” (USDA.gov). Conventional agriculture was developed to make farming more efficient, but achieves that efficiency at a major cost to the environment.
The goal of conventional agriculture is to maximize the potential yield of crops. This is achieved through the application of synthetic chemicals, genetically modified organisms, and a number of other industrial products. In maintaining a conventional system, biodiversity, soil fertility, and ecosystems health are compromised (Huntley, Collins, and Swisher). Production of these crops is beneficial to nothing but food security and economy. Once established, a conventional farm requires constant maintenance but produces maximal yields.
Maintenance is made easy for farmers as conventional farming typically involves monocropping, but is also very expensive. In a conventional system farmers will designate entire fields to just one crop, which creates uniformity. Uniformity can determine both the success and failure of conventional systems. A uniform crop is ideal because it reduces labor costs and makes harvesting easy, but it can also impact biodiversity and make crops susceptible to pathogens (Gabriel, Salt, Kunin, and Benton 2013). Chemicals and genetically modified organisms make maintenance of conventional systems relatively simple for farmers, but require a constant input of energy and money. In a conventional system, farmers can apply pesticides and herbicides to crops at a much more efficient rate if they are made up of just one type of plant, but this has a number of unintended consequences. Since the goal of conventional agriculture is to maximize yields, environmental health and biodiversity are usually not preserved.
IV. Sustainable Agriculture
Where conventional farming represents one extreme of agriculture, sustainable farming represents the other. “Organic agriculture is a production system that sustains the health of soils, ecosystems and people. It relies on ecological processes, biodiversity and cycles adapted to local conditions, rather than the use of inputs with adverse effects. Organic agriculture combines tradition, innovation and science to benefit the shared environment and promote fair relationships and a good quality of life for all involved.” (Gomiero, Pimentel, and Paoletti 2011). Sustainable agriculture is a more holistic approach to farming than conventional in that it relies on ecosystem services and is typically much less detrimental to the surrounding landscape. Sustainable agriculture is a natural way to produce food and has a number of social, economic, and environmental benefits.
There are many types of sustainable farming that all rely on natural cycles to ensure plant health and crop performance. Sustainable farming forgoes the use of synthetic pesticides, herbicides, and fertilizers to produce food. Instead, farmers will plant a variety of plants together to promote biodiversity and ward off pests and pathogens (Nicholls and Altieri 2012). Where conventional systems promote uniformity and depend on synthetic chemicals for protection against disease and pests, sustainable systems rely on biodiversity as a measure to protect against these things.
Sustainable agriculture profits farmers, economies, and food banks while existing symbiotically with the landscape. One example of many in sustainable farming practices, which emphasizes economic benefits and environmental health, is conservation agriculture. “By increasing soil organic matter contents and moisture-holding capacity, CA can double subsistence crop yields in areas where use of fertilizers is uneconomic and it can sustain production in years with low rainfall.” (Kassam and Brammer 2013). Conservation agriculture underlines the focus of sustainable agriculture in that it focuses on producing high yields without compromising the integrity of the environment.
V. A Comparison of Agriculture
In a comparison of conventional and sustainable agriculture there should be several points of focus: production, biodiversity, soil composition / erosion, water use, energy use, and greenhouse gas emissions. The environmental impact and production levels of each method will determine its overall viability as a solution to growing trends. It is necessary to make these comparisons in order to identify the best agricultural method that can sustainably meet the needs of the current population. Although these comparisons are based off of scientific data, there is much more research that needs to be done in order to make a definitive judgment.
To meet the needs of the current population requires a tremendous amount of resources. Not taking into account the environmental damage associated with intense production, conventional agriculture is a feasible way to provide for more people; “… population growth and increasing consumption of calorie- and meat-intensive diets are expected to roughly double human food demand by 2050.” (Mueller, Gerber, Johnston, Ray, Ramankutty, and Foley 2012). In addressing this rapid growth, production levels become a serious point of comparison. “Organic yields are globally on average 25% lower than conventional yields according to a recent meta-analysis, although this varies with crop types and species and depends on the comparability of farming systems.” (Gabriel, Salt, Kunin, and Benton 2013). Most research indicates that sustainable crops produce much less than conventional systems.
There are many environmental benefits associated with sustainable agriculture, but its production capacity is limited. In general, sustainable agriculture fails to match up to conventional agriculture in terms of production. This result varies though, and in some instances organic crops actually best conventional crops. For example, under drought conditions organic crops tend to produce higher yields because they typically retain more water; “As part of the Rodale Institute Farming System Trial (from 1981 to 2002), Pimentel et al., (2005) found that during 1999, a year of extreme drought, (with total rainfall between April and August of 224 mm, compared with an average of 500 mm) the organic animal system had significantly higher corn yield (1,511 kg per ha) than either organic legume (412 kg per ha) or the conventional (1,100 kg per ha).” (Gomiero, Pimentel, and Paoletti 2011). Although certain conditions may favor organic crops, conventional agriculture is designed to produce the highest yields possible.
Many factors contribute to this difference in production. Conventional crops are designed specifically to produce maximal yields; therefore, the difference should be expected. Typically conventional crops are genetically modified to perform better under certain conditions than sustainable crops (Carpenter 2011). However, these crops are also sprayed with toxic pesticides and herbicides to make up for their uniformity. Some research has been done to determine whether increased biodiversity is related to increased yields; “…farmland biodiversity is typically negatively related to crop yield; generally, organic farming per se does not have an effect other than via reducing yields and therefore increasing biodiversity.” (Gabriel, Salt, Kunin, and Benton 2013). Although levels of production are reduced in sustainable agriculture, studies show that higher levels of biodiversity are linked to healthier crops.
Biodiversity plays a large part in this comparison because it is a determinant of agricultural health and performance. The greater the biodiversity, the more immune plants are to pests and disease (Gomiero, Pimentel, and Paoletti 2011). This is important to highlight because conventional agriculture discourages biodiversity and instead relies on synthetic chemicals to maintain crop health. Over 940 million pounds of pesticides are being applied annually with only 10% of that reaching the desired target, a number that could be greatly reduced if conventional agriculture were to implement sustainable alternatives (Sustainablelafayette.org). Techniques such as integrated pest management and intercropping could be applied to conventional systems and in turn promote biodiversity.
High biodiversity is important to sustainable farming because it enhances the performance of the ecological cycles that the crops depend upon. Organic agricultural systems are typically much more rich in nutrients and diverse in organisms than conventional systems; “…organic farming is usually associated with a significantly higher level of biological activity, represented by bacteria, fungi, springtails, mites and earthworms, due to its versatile crop rotations, reduced applications of nutrients, and the ban on pesticides.” (Gomiero, Pimentel, and Paoletti 2011). It is important to encourage high nutrient levels and biodiversity as these two factors contribute significantly to the health of the crops and the landscape. Although biodiversity does not directly determine crop yield, it does play a major role in the health and permanence of sustainable farms.
Despite the impacts conventional methods have on agricultural land, not all conventional farms degrade biodiversity. In fact, there are many ways farmers can reduce the amount of chemicals and energy they use by implementing low input alternatives; “Overall, the review finds that currently commercialized GM crops have reduced the impacts of agriculture on biodiversity, through enhanced adoption of conservation tillage practices, reduction of insecticide use and use of more environmentally benign herbicides and increasing yields to alleviate pressure to convert additional land into agricultural use.” (Carpenter 2011). The global impact agriculture has can be significantly reduced if conventional farmers adopt sustainable techniques.
In addition to higher levels of biodiversity, sustainable farming is typically associated with better soil quality. Organic farms have stronger soil ecology because they promote biodiversity rather than uniformity; “The results confirm that higher levels of total and organic C, total N and soluble organic C are observed in all of the organic soil.” (Wang, Li, and Fan 2012). The increased concentrations of these nutrients can be contributed to the depth of the food web and amount of biomass in sustainable systems. “In a seven-year experiment in Italy, Marinari et al. (2006) compared two adjacent farms, one organic and one conventional, and found that the fields under organic management showed significantly better soil nutritional and microbiological conditions; with an increased level of total nitrogen, nitrate and available phosphorus, and an increased microbial biomass content, and enzymatic activities.” (Gomiero, Pimentel, and Paoletti 2011). Sustainable crops are more permanent than conventional crops because they work in harmony with the landscape rather than drain it of nutrients and biomass.
Soil management is vital for existing farms because agricultural production is increasing globally and land is becoming less available to accommodate this growth. Conventional systems can improve soil quality by practicing sustainable methods like no-tillage farming, agroforestry, and integrated pest management, but sustainable agriculture is the most effective form of food production in terms of maintaining soil conditions. “Establishing trees on agricultural land can help to mitigate many of the negative impacts of agriculture, for example by regulating soil, water and air quality, supporting biodiversity, reducing inputs by natural regulation of pests and more efficient nutrient cycling, and by modifying local and global climates.” (Smith, Pearce, and Wolfe 2012). Again, research shows that an increase in biodiversity and a reduction of chemical input can result in conventional farms with more healthy soils and improved crop performance.
A major problem concerning agriculture is soil erosion caused by nutrient loss, run-off, salinity, and drought. Soil erosion presents a threat to the growth of agriculture because, “Intensive farming exacerbates these phenomena, which are threatening the future sustainability of crop production on a global scale, especially under extreme climatic events such as droughts.” (Gomiero, Pimentel, and Paoletti 2011). Organic systems enhance soil composition as well as prevent soil erosion due to the greater amount of plant material and biomass in the soil. Conventional systems manipulate the landscape rather than adapt to it; “…soils under organic management showed <75% soil loss compared to the maximum tolerance value in the region (the maximum rate of soil erosion that can occur without compromising long-term crop productivity or environmental quality −11.2 t ha−1 yr−1), while in conventional soil a rate of soil loss three times the maximum tolerance value was recorded.” (Gomiero, Pimentel, and Paoletti 2011). Compared to sustainable farming, conventional crops are terribly inefficient at maintaining the integrity of agricultural landscapes. Conventional agriculture is therefore unable meet the demands of the growing populations without consuming a substantial amount of land and non-renewable resources.
On a global scale, water is a renewable resource that can meet the needs of our current population. Locally, however, water is a scarce resource and must be appropriated efficiently. The amount of fresh water available for consumption globally is small, but regional constraints make accessing that water even more difficult for many millions of people. Agriculture accounts for approximately 70% of water use worldwide (USDA.gov). Increasing demand for fresh water is pressuring global stocks. To conserve this resource a drastic overhaul of water saving techniques, especially in agriculture, must occur.
Due to the abundance of flora and fauna in sustainable systems, organic soil typically retains much more water than conventional soil. This increased retention rate enables sustainable agricultural systems to produce much higher yields than conventional systems during drought conditions (Gomiero, Pimentel, and Paoletti 2011). This is a desirable characteristic in agricultural land as it allows crops to be more tolerable to changing climate. “In heavy loess soils in a temperate climate in Switzerland water holding capacity was reported being 20 to 40% higher in organically managed soils than in conventional ones… The primary reason for higher yield in organic crops is thought to be due to the higher water-holding capacity of the soils under organic management.” (Gomiero, Pimentel, and Paoletti 2011). To manage available water resources, sustainable agriculture is the more efficient approach to feeding the world.
A gap exists between current production rates and potential production rates of crops. Through better management of water and soil, much greater yields can be produced. Increasing efficiency to 100% is not entirely feasible, but implementing sustainable farming techniques would conserve resources and improve crop performance; “Globally, we find that closing yield gaps to 100% of attainable yields could increase worldwide crop production by 45% to 70% for most major crops (with 64%, 71% and 47% increases for maize, wheat and rice, respectively).” (Mueller, Gerber, Johnston, Ray, Ramankutty, and Foley 2012). Meeting future food demands is a dynamic problem that requires consideration of all things, but most importantly water and soil conservation.
Sustainable agriculture relies solely on natural processes for input and recycles nutrients on-site to eliminate the use of non-renewable resources. Alternatively, conventional agriculture requires an incredible amount of energy to produce, prepare, and transport food. Energy efficiency is important to agriculture as it can reduce greenhouse gas emissions and lower costs of production; “Agricultural activities (not including forest conversion) account for approximately 5% of anthropogenic emissions of CO2 and the 10–12% of total global anthropogenic emissions of GHGs (5.1 to 6.1 Gt CO2 eq. yr−1 in 2005), accounting for nearly all the anthropogenic methane and one to two thirds of all anthropogenic nitrous oxide emissions are due to agricultural activities.” (Gomiero, Pimentel, and Paoletti 2011). Agriculture is responsible for a significant percentage of greenhouse gas emissions, but can also mitigate this impact using sustainable methods. Better management of agricultural land is required to reduce the effects of crop production.
Sustainable agriculture has the ability to offset global greenhouse emissions at a greater rate than conventional agriculture because it is more permanent and does not require much input to produce food. Conventional systems are inefficient at capturing carbon because of soil composition, constant production, and how much energy is being used to maintain the crops. “We use so much machinery, pesticides, irrigation, processing, and transportation that for every calorie that comes to the table, 10 calories or energy have been expended.” (Sustainablelafayette.org). However, there are measures that can be taken to increase energy efficiency. “This carbon can be stored in soil by SOM and by aboveground biomass through processes such as adopting rotations with cover crops and green manures to increase SOM, agroforestry, and conservation-tillage systems.” (Gomiero, Pimentel, and Paoletti 2011). Conventional agriculture operates at a net energy loss, but implementing sustainable practices can reduce costs and benefit the surrounding landscape.
Sustainable agriculture aims to enhance the composition of a landscape while producing sufficient yields. This method is so efficient compared to conventional agriculture because it requires no input of synthetic chemicals or fertilizers, which accounts for a large amount of the greenhouse gas emissions. However, energy efficiency also takes into account the ratio of input to output. In that sense, there is no substantial difference between the two types of agriculture; “…the energy efficiency, calculated as the yield divided by the energy use (MJ ha−1), was generally higher in the organic system than in the conventional system, but the yields were also lower. This meant that conventional crop production had the highest net energy production, whereas organic crop production had the highest energy efficiency.” (Gomiero, Pimentel, and Paoletti 2011). Even though conventional systems produce greater yields than sustainable systems, organic crop production is the most energy efficient method.
Studies point toward sustainable agriculture as the best solution to managing the growing population. Although the benefits of sustainable agriculture are abundant, there are several constraints to adopting this method worldwide. Climate conditions vary with geography so where sustainable agriculture is the most efficient system in one part of the world, it may not be entirely feasible in another. “Some authors suggest the adoption of integrated farming, rather than upholding solely organic practices, which they find more harmful than conventional farming, for instance in the case of pest control technologies.” (Gomiero, Pimentel, and Paoletti 2011). Many factors determine the performance of agricultural methods and often the most effective type of agriculture requires a combination of techniques. In addition to local constraints, sustainable agriculture also requires much more labor to maintain crops.
The science of agriculture has allowed human populations to grow exponentially and dominate the world’s landscapes. Advancements in this science have enabled humans to manipulate entire ecosystems to cater to their survival. But as populations continue to grow, resources are becoming limited. Water, fuel, and soil are three important factors determining the survival the world’s population and it is crucial that they are used as efficiently as possible. In a comparison of sustainable and conventional agriculture, organic farming methods are shown to perform much better for a number of indicators. Sustainable agriculture consumes less water and energy, enhances soil composition, and forgoes synthetic chemical input. Conventional agriculture cannot meet the needs of the current population without compromising the integrity of the environment. Sustainable agriculture has the potential to sequester carbon, feed the world, and enrich the environment. The social, economic, and environmental benefits of this system are reasons why sustainable agriculture is the most viable way to accommodate growing trends.
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The goal of sustainable agriculture is to meet society’s food and textile needs in the present without compromising the ability of future generations to meet their own needs. Practitioners of sustainable agriculture seek to integrate three main objectives into their work: a healthy environment, economic profitability, and social and economic equity. Every person involved in the food system—growers, food processors, distributors, retailers, consumers, and waste managers—can play a role in ensuring a sustainable agricultural system.
There are many practices commonly used by people working in sustainable agriculture and sustainable food systems. Growers may use methods to promote soil health, minimize water use, and lower pollution levels on the farm. Consumers and retailers concerned with sustainability can look for “values-based” foods that are grown using methods promoting farmworker wellbeing, that are environmentally friendly, or that strengthen the local economy. And researchers in sustainable agriculture often cross disciplinary lines with their work: combining biology, economics, engineering, chemistry, community development, and many others. However, sustainable agriculture is more than a collection of practices. It is also process of negotiation: a push and pull between the sometimes competing interests of an individual farmer or of people in a community as they work to solve complex problems about how we grow our food and fiber.
The rest of this page delves further into the philosophy and practices underpinning sustainable agriculture. Or visit the links to the right to visit practical pages for practicing sustainable agriculture.
- Since World War II the number of U.S. farms has declined and the average farm size has increased. Data from USDA Census of Agriculture.
Agriculture has changed dramatically, especially since the end of World War II. Food and fiber productivity soared due to new technologies, mechanization, increased chemical use, specialization and government policies that favored maximizing production. These changes allowed fewer farmers with reduced labor demands to produce the majority of the food and fiber in the U.S.
Although these changes have had many positive effects and reduced many risks in farming, there have also been significant costs. Prominent among these are topsoil depletion, groundwater contamination, the decline of family farms, continued neglect of the living and working conditions for farm laborers, increasing costs of production, and the disintegration of economic and social conditions in rural communities.
Potential Costs of Modern Agricultural Techniques
A growing movement has emerged during the past two decades to question the role of the agricultural establishment in promoting practices that contribute to these social problems. Today this movement for sustainable agriculture is garnering increasing support and acceptance within mainstream agriculture. Not only does sustainable agriculture address many environmental and social concerns, but it offers innovative and economically viable opportunities for growers, laborers, consumers, policymakers and many others in the entire food system.
This page is an effort to identify the ideas, practices and policies that constitute our concept of sustainable agriculture. We do so for two reasons: 1) to clarify the research agenda and priorities of our program, and 2) to suggest to others practical steps that may be appropriate for them in moving toward sustainable agriculture. Because the concept of sustainable agriculture is still evolving, we intend this page not as a definitive or final statement, but as an invitation to continue the dialogue.
What is Sustainable Agriculture?
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Sustainable agriculture integrates three main goals — environmental health, economic profitability, and social and economic equity.
A variety of philosophies, policies and practices have contributed to these goals. People in many different capacities, from farmers to consumers, have shared this vision and contributed to it.
Despite the diversity of people and perspectives, the following themes commonly weave through definitions of sustainable agriculture:
Sustainability rests on the principle that we must meet the needs of the present without compromising the ability of future generations to meet their own needs.
Therefore, stewardship of both natural and human resources is of prime importance. Stewardship of human resources includes consideration of social responsibilities such as working and living conditions of laborers, the needs of rural communities, and consumer health and safety both in the present and the future. Stewardship of land and natural resources involves maintaining or enhancing this vital resource base for the long term.
A systems perspective is essential to understanding sustainability.
The system is envisioned in its broadest sense, from the individual farm, to the local ecosystem, and to communities affected by this farming system both locally and globally. An emphasis on the system allows a larger and more thorough view of the consequences of farming practices on both human communities and the environment. A systems approach gives us the tools to explore the interconnections between farming and other aspects of our environment.
A systems approach also implies interdisciplinary efforts in research and education.
This requires not only the input of researchers from various disciplines, but also farmers, farmworkers, consumers, policymakers and others.
Making the transition to sustainable agriculture is a process.
For farmers, the transition to sustainable agriculture normally requires a series of small, realisticsteps. Family economics and personal goals influence how fast or how far participants can go in the transition. It is important to realize that each small decision can make a difference and contribute to advancing the entire system further on the "sustainable agriculture continuum." The key to moving forward is the will to take the next step.
Finally, it is important to point out thatreaching toward the goal of sustainable agriculture is the responsibility of all participants in the system, including farmers, laborers, policymakers, researchers, retailers, and consumers. Each group has its own part to play, its own unique contribution to make to strengthen the sustainable agriculture community.
The remainder of this page considers specific strategies for realizing these broad themes or goals. The strategies are grouped according to three separate though related areas of concern: Farming and Natural Resources, Plant and Animal Production Practices, and the Economic, Social and Political Context. They represent a range of potential ideas for individuals committed to interpreting the vision of sustainable agriculture within their own circumstances.
Farming and Natural Resources
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When the production of food and fiber degrades the natural resource base, the ability of future generations to produce and flourish decreases. The decline of ancient civilizations in Mesopotamia, the Mediterranean region, Pre-Columbian southwest U.S. and Central America is believed to have been strongly influenced by natural resource degradation from non-sustainable farming and forestry practices.
Water is the principal resource that has helped agriculture and society to prosper, and it has been a major limiting factor when mismanaged.
Water supply and use. In California, an extensive water storage and transfer system has been established which has allowed crop production to expand to very arid regions. In drought years, limited surface water supplies have prompted overdraft of groundwater and consequent intrusion of salt water, or permanent collapse of aquifers. Periodic droughts, some lasting up to 50 years, have occurred in California.
Several steps should be taken to develop drought-resistant farming systems even in "normal" years, including both policy and management actions:
1) improving water conservation and storage measures,
2) providing incentives for selection of drought-tolerant crop species,
3) using reduced-volume irrigation systems,
4) managing crops to reduce water loss, or
5) not planting at all.
Water quality. The most important issues related to water quality involve salinization and contamination of ground and surface waters by pesticides, nitrates and selenium. Salinity has become a problem wherever water of even relatively low salt content is used on shallow soils in arid regions and/or where the water table is near the root zone of crops. Tile drainage can remove the water and salts, but the disposal of the salts and other contaminants may negatively affect the environment depending upon where they are deposited. Temporary solutions include the use of salt-tolerant crops, low-volume irrigation, and various management techniques to minimize the effects of salts on crops. In the long-term, some farmland may need to be removed from production or converted to other uses. Other uses include conversion of row crop land to production of drought-tolerant forages, the restoration of wildlife habitat or the use of agroforestry to minimize the impacts of salinity and high water tables. Pesticide and nitrate contamination of water can be reduced using many of the practices discussed later in the Plant Production Practices and Animal Production Practices sections.
Wildlife. Another way in which agriculture affects water resources is through the destruction of riparian habitats within watersheds. The conversion of wild habitat to agricultural land reduces fish and wildlife through erosion and sedimentation, the effects of pesticides, removal of riparian plants, and the diversion of water. The plant diversity in and around both riparian and agricultural areas should be maintained in order to support a diversity of wildlife. This diversity will enhance natural ecosystems and could aid in agricultural pest management.
Modern agriculture is heavily dependent on non-renewable energy sources, especially petroleum. The continued use of these energy sources cannot be sustained indefinitely, yet to abruptly abandon our reliance on them would be economically catastrophic. However, a sudden cutoff in energy supply would be equally disruptive. In sustainable agricultural systems, there is reduced reliance on non-renewable energy sources and a substitution of renewable sources or labor to the extent that is economically feasible.
Many agricultural activities affect air quality. These include smoke from agricultural burning; dust from tillage, traffic and harvest; pesticide drift from spraying; and nitrous oxide emissions from the use of nitrogen fertilizer. Options to improve air quality include:
- incorporating crop residue into the soil
- using appropriate levels of tillage
- and planting wind breaks, cover crops or strips of native perennial grasses to reduce dust.
Soil erosion continues to be a serious threat to our continued ability to produce adequate food. Numerous practices have been developed to keep soil in place, which include:
- reducing or eliminating tillage
- managing irrigation to reduce runoff
- and keeping the soil covered with plants or mulch.
Enhancement of soil quality is discussed in the next section.
Plant Production Practices
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Sustainable production practices involve a variety of approaches. Specific strategies must take into account topography, soil characteristics, climate, pests, local availability of inputs and the individual grower's goals. Despite the site-specific and individual nature of sustainable agriculture, several general principles can be applied to help growers select appropriate management practices:
- Selection of species and varieties that are well suited to the site and to conditions on the farm;
- Diversification of crops (including livestock) and cultural practices to enhance the biological and economic stability of the farm;
- Management of the soil to enhance and protect soil quality;
- Efficient and humane use of inputs; and
- Consideration of farmers' goals and lifestyle choices.
Selection of site, species and variety
Preventive strategies, adopted early, can reduce inputs and help establish a sustainable production system. When possible, pest-resistant crops should be selected which are tolerant of existing soil or site conditions. When site selection is an option, factors such as soil type and depth, previous crop history, and location (e.g. climate, topography) should be taken into account before planting.
Diversified farms are usually more economically and ecologically resilient. While monoculture farming has advantages in terms of efficiency and ease of management, the loss of the crop in any one year could put a farm out of business and/or seriously disrupt the stability of a community dependent on that crop. By growing a variety of crops, farmers spread economic risk and are less susceptible to the radical price fluctuations associated with changes in supply and demand.
Properly managed, diversity can also buffer a farm in a biological sense. For example, in annual cropping systems, crop rotation can be used to suppress weeds, pathogens and insect pests. Also, cover crops can have stabilizing effects on the agroecosystem by holding soil and nutrients in place, conserving soil moisture with mowed or standing dead mulches, and by increasing the water infiltration rate and soil water holding capacity. Cover crops in orchards and vineyards can buffer the system against pest infestations by increasing beneficial arthropod populations and can therefore reduce the need for chemical inputs. Using a variety of cover crops is also important in order to protect against the failure of a particular species to grow and to attract and sustain a wide range of beneficial arthropods.
Optimum diversity may be obtained by integrating both crops and livestock in the same farming operation. This was the common practice for centuries until the mid-1900s when technology, government policy and economics compelled farms to become more specialized. Mixed crop and livestock operations have several advantages. First, growing row crops only on more level land and pasture or forages on steeper slopes will reduce soil erosion. Second, pasture and forage crops in rotation enhance soil quality and reduce erosion; livestock manure, in turn, contributes to soil fertility. Third, livestock can buffer the negative impacts of low rainfall periods by consuming crop residue that in "plant only" systems would have been considered crop failures. Finally, feeding and marketing are flexible in animal production systems. This can help cushion farmers against trade and price fluctuations and, in conjunction with cropping operations, make more efficient use of farm labor.
A common philosophy among sustainable agriculture practitioners is that a "healthy" soil is a key component of sustainability; that is, a healthy soil will produce healthy crop plants that have optimum vigor and are less susceptible to pests. While many crops have key pests that attack even the healthiest of plants, proper soil, water and nutrient management can help prevent some pest problems brought on by crop stress or nutrient imbalance. Furthermore, crop management systems that impair soil quality often result in greater inputs of water, nutrients, pesticides, and/or energy for tillage to maintain yields.
In sustainable systems, the soil is viewed as a fragile and living medium that must be protected and nurtured to ensure its long-term productivity and stability. Methods to protect and enhance the productivity of the soil include:
- using cover crops, compost and/or manures
- reducing tillage
- avoiding traffic on wet soils
- maintaining soil cover with plants and/or mulches
Conditions in most California soils (warm, irrigated, and tilled) do not favor the buildup of organic matter. Regular additions of organic matter or the use of cover crops can increase soil aggregate stability, soil tilth, and diversity of soil microbial life.
Efficient use of inputs
Many inputs and practices used by conventional farmers are also used in sustainable agriculture. Sustainable farmers, however, maximize reliance on natural, renewable, and on-farm inputs. Equally important are the environmental, social, and economic impacts of a particular strategy. Converting to sustainable practices does not mean simple input substitution. Frequently, it substitutes enhanced management and scientific knowledge for conventional inputs, especially chemical inputs that harm the environment on farms and in rural communities. The goal is to develop efficient, biological systems which do not need high levels of material inputs.
Growers frequently ask if synthetic chemicals are appropriate in a sustainable farming system. Sustainable approaches are those that are the least toxic and least energy intensive, and yet maintain productivity and profitability. Preventive strategies and other alternatives should be employed before using chemical inputs from any source. However, there may be situations where the use of synthetic chemicals would be more "sustainable" than a strictly nonchemical approach or an approach using toxic "organic" chemicals. For example, one grape grower switched from tillage to a few applications of a broad spectrum contact herbicide in the vine row. This approach may use less energy and may compact the soil less than numerous passes with a cultivator or mower.
Consideration of farmer goals and lifestyle choices
Management decisions should reflect not only environmental and broad social considerations, but also individual goals and lifestyle choices. For example, adoption of some technologies or practices that promise profitability may also require such intensive management that one's lifestyle actually deteriorates. Management decisions that promote sustainability, nourish the environment, the community and the individual.
Animal Production Practices
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In the early part of this century, most farms integrated both crop and livestock operations. Indeed, the two were highly complementary both biologically and economically. The current picture has changed quite drastically since then. Crop and animal producers now are still dependent on one another to some degree, but the integration now most commonly takes place at a higher level--between farmers, through intermediaries, rather than within the farm itself. This is the result of a trend toward separation and specialization of crop and animal production systems. Despite this trend, there are still many farmers, particularly in the Midwest and Northeastern U.S. that integrate crop and animal systems--either on dairy farms, or with range cattle, sheep or hog operations.
Even with the growing specialization of livestock and crop producers, many of the principles outlined in the crop production section apply to both groups. The actual management practices will, of course, be quite different. Some of the specific points that livestock producers need to address are listed below.
Including livestock in the farming system increases the complexity of biological and economic relationships. The mobility of the stock, daily feeding, health concerns, breeding operations, seasonal feed and forage sources, and complex marketing are sources of this complexity. Therefore, a successful ranch plan should include enterprise calendars of operations, stock flows, forage flows, labor needs, herd production records and land use plans to give the manager control and a means of monitoring progress toward goals.
The animal enterprise must be appropriate for the farm or ranch resources. Farm capabilities and constraints such as feed and forage sources, landscape, climate and skill of the manager must be considered in selecting which animals to produce. For example, ruminant animals can be raised on a variety of feed sources including range and pasture, cultivated forage, cover crops, shrubs, weeds, and crop residues. There is a wide range of breeds available in each of the major ruminant species, i.e., cattle, sheep and goats. Hardier breeds that, in general, have lower growth and milk production potential, are better adapted to less favorable environments with sparse or highly seasonal forage growth.
Feed costs are the largest single variable cost in any livestock operation. While most of the feed may come from other enterprises on the ranch, some purchased feed is usually imported from off the farm. Feed costs can be kept to a minimum by monitoring animal condition and performance and understanding seasonal variations in feed and forage quality on the farm. Determining the optimal use of farm-generated by-products is an important challenge of diversified farming.
Use of quality germplasm to improve herd performance is another key to sustainability. In combination with good genetic stock, adapting the reproduction season to fit the climate and sources of feed and forage reduce health problems and feed costs.
Animal health greatly influences reproductive success and weight gains, two key aspects of successful livestock production. Unhealthy stock waste feed and require additional labor. A herd health program is critical to sustainable livestock production.
Most adverse environmental impacts associated with grazing can be prevented or mitigated with proper grazing management. First, the number of stock per unit area (stocking rate) must be correct for the landscape and the forage sources. There will need to be compromises between the convenience of tilling large, unfenced fields and the fencing needs of livestock operations. Use of modern, temporary fencing may provide one practical solution to this dilemma. Second, the long term carrying capacity and the stocking rate must take into account short and long-term droughts. Especially in Mediterranean climates such as in California, properly managed grazing significantly reduces fire hazards by reducing fuel build-up in grasslands and brushlands. Finally, the manager must achieve sufficient control to reduce overuse in some areas while other areas go unused. Prolonged concentration of stock that results in permanent loss of vegetative cover on uplands or in riparian zones should be avoided. However, small scale loss of vegetative cover around water or feed troughs may be tolerated if surrounding vegetative cover is adequate.
Confined Livestock Production
Animal health and waste management are key issues in confined livestock operations. The moral and ethical debate taking place today regarding animal welfare is particularly intense for confined livestock production systems. The issues raised in this debate need to be addressed.
Confinement livestock production is increasingly a source of surface and ground water pollutants, particularly where there are large numbers of animals per unit area. Expensive waste management facilities are now a necessary cost of confined production systems. Waste is a problem of almost all operations and must be managed with respect to both the environment and the quality of life in nearby communities. Livestock production systems that disperse stock in pastures so the wastes are not concentrated and do not overwhelm natural nutrient cycling processes have become a subject of renewed interest.
The Economic, Social & Political Context
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In addition to strategies for preserving natural resources and changing production practices, sustainable agriculture requires a commitment to changing public policies, economic institutions, and social values. Strategies for change must take into account the complex, reciprocal and ever-changing relationship between agricultural production and the broader society.
The "food system" extends far beyond the farm and involves the interaction of individuals and institutions with contrasting and often competing goals including farmers, researchers, input suppliers, farmworkers, unions, farm advisors, processors, retailers, consumers, and policymakers. Relationships among these actors shift over time as new technologies spawn economic, social and political changes.
A wide diversity of strategies and approaches are necessary to create a more sustainable food system. These will range from specific and concentrated efforts to alter specific policies or practices, to the longer-term tasks of reforming key institutions, rethinking economic priorities, and challenging widely-held social values. Areas of concern where change is most needed include the following:
Food and agricultural policy
Existing federal, state and local government policies often impede the goals of sustainable agriculture. New policies are needed to simultaneously promote environmental health, economic profitability, and social and economic equity. For example, commodity and price support programs could be restructured to allow farmers to realize the full benefits of the productivity gains made possible through alternative practices. Tax and credit policies could be modified to encourage a diverse and decentralized system of family farms rather than corporate concentration and absentee ownership. Government and land grant university research policies could be modified to emphasize the development of sustainable alternatives. Marketing orders and cosmetic standards could be amended to encourage reduced pesticide use. Coalitions must be created to address these policy concerns at the local, regional, and national level.
Conversion of agricultural land to urban uses is a particular concern in California, as rapid growth and escalating land values threaten farming on prime soils. Existing farmland conversion patterns often discourage farmers from adopting sustainable practices and a long-term perspective on the value of land. At the same time, the close proximity of newly developed residential areas to farms is increasing the public demand for environmentally safe farming practices. Comprehensive new policies to protect prime soils and regulate development are needed, particularly in California's Central Valley. By helping farmers to adopt practices that reduce chemical use and conserve scarce resources, sustainable agriculture research and education can play a key role in building public support for agricultural land preservation. Educating land use planners and decision-makers about sustainable agriculture is an important priority.
In California, the conditions of agricultural labor are generally far below accepted social standards and legal protections in other forms of employment. Policies and programs are needed to address this problem, working toward socially just and safe employment that provides adequate wages, working conditions, health benefits, and chances for economic stability. The needs of migrant labor for year-around employment and adequate housing are a particularly crucial problem needing immediate attention. To be more sustainable over the long-term, labor must be acknowledged and supported by government policies, recognized as important constituents of land grant universities, and carefully considered when assessing the impacts of new technologies and practices.
Rural Community Development
Rural communities in California are currently characterized by economic and environmental deterioration. Many are among the poorest locations in the nation. The reasons for the decline are complex, but changes in farm structure have played a significant role. Sustainable agriculture presents an opportunity to rethink the importance of family farms and rural communities. Economic development policies are needed that encourage more diversified agricultural production on family farms as a foundation for healthy economies in rural communities. In combination with other strategies, sustainable agriculture practices and policies can help foster community institutions that meet employment, educational, health, cultural and spiritual needs.
Consumers and the Food System
Consumers can play a critical role in creating a sustainable food system. Through their purchases, they send strong messages to producers, retailers and others in the system about what they think is important. Food cost and nutritional quality have always influenced consumer choices. The challenge now is to find strategies that broaden consumer perspectives, so that environmental quality, resource use, and social equity issues are also considered in shopping decisions. At the same time, new policies and institutions must be created to enable producers using sustainable practices to market their goods to a wider public. Coalitions organized around improving the food system are one specific method of creating a dialogue among consumers, retailers, producers and others. These coalitions or other public forums can be important vehicles for clarifying issues, suggesting new policies, increasing mutual trust, and encouraging a long-term view of food production, distribution and consumption.
FOR MORE INFORMATION:
Contact the UC Sustainable Agriculture Research and Education Program, University of California, Davis, CA 95616, (530) 752-7556. Written by Gail Feenstra, Writer; Chuck Ingels, Perennial Cropping Systems Analyst; and David Campbell, Economic and Public Policy Analyst with contributions from David Chaney, Melvin R. George, Eric Bradford, the staff and advisory committees of the UC Sustainable Agriculture Research and Education Program.
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