For example, farmers aiming for a higher level of environmental sustainability might consider how they can reduce their use of toxic pesticides by bringing natural processes to bear on limiting pest populations. This might happen, for example, by planting hedgerows along field edges, or ground covers between rows, thereby providing habitat for insects and birds that prey on the pests, or by planting more diverse blends of crops that confuse or deflect pests Figure 2.
Maintaining a high degree of genetic diversity by conserving as many crop varieties and animal breeds as possible will also provide more genetic resources for breeding resistance to diseases and pests.
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Figure 2 A clover and grass cover crop adds biodiversity to an almond orchard, which aids in nutrient cycling and provides habitat for beneficial insects, while also building soil organic matter. Conservation of resources critical for agricultural productivity also means taking care of soil so that it maintains its integrity as a complex and highly structured entity composed of mineral particles, organic matter, air, water, and living organisms. Farmers interested in long-term sustainability often prioritize caring for the soil, because they recognize that a healthy soil promotes healthy crops and livestock.
Maintaining soil functioning often means a focus on maintaining or even increasing soil organic matter. Soil organic matter functions as a crucial source and sink for nutrients, as a substrate for microbial activity, and as a buffer against fluctuations in acidity, water content, contaminants, etc. Furthermore, the buildup of soil organic matter can help mitigate the increase of atmospheric CO 2 and therefore climate change. Another important function of soil organic matter is inducing a better soil structure, which leads to improved water penetration, less runoff, better drainage, and increased stability, thereby reducing wind and water erosion.
Due to a high reliance on chemical fertilizers, agroecosystem functioning has been disconnected from the internal cycling of key plant nutrients such as nitrogen and phosphorus. Phosphate minerals for fertilizer are currently mined, but global reserves are predicted to sustain food production for only another 50 to years. Consequently, phosphate prices are anticipated to rise unless new reserves are discovered and innovations in recovery of phosphates from waste are developed.
The recycling of nitrogen and phosphorus at the farm and regional scale , improving efficiencies of fertilizer applications, and relying on organic nutrient sources animal and green manures are important elements of sustainable agriculture Figure 3. Recycling of nutrients is facilitated by a diversified agriculture in which livestock and crop production are more spatially integrated. For these reasons, extensive mixed crop-livestock systems, particularly in developing countries, could significantly contribute to future agricultural sustainability and global food security.
The practice has been shown to reduce soil erosion, increase yield, increase biotic activity, improve soil structure, and enhance soil organic matter accumulation. Overdraft of surface waters results in disturbance of key riparian zones, while overdraft of groundwater supplies threatens future irrigation capacity. Salinization, nutrient overloads, and pesticide contamination are widespread water quality issues. Selection and breeding of more drought- and salt-tolerant crop species and hardier animal breeds, use of reduced-volume irrigation systems, and management of soils and crops to reduce water loss are all ways to use water more efficiently within sustainable agroecosystems.
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Modern agriculture is heavily dependent on non-renewable energy sources, especially petroleum. The continued use of these non-renewable sources cannot be sustained indefinitely, yet to abruptly abandon our reliance on them would be economically catastrophic. In sustainable agriculture, the goal is to reduce the input of external energy and to substitute non-renewable energy sources with renewable sources e. Feenstra, G. What is Sustainable Agriculture? Altieri, M. Agroecology: The Science of Sustainable Agriculture.
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Boulder, CO: Westview Press, Gliessman, S. Agroecology: Ecological Processes in Sustainable Agriculture. Hinrichs, C. Soil: The Foundation of Agriculture.
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1. What challenges does agriculture face today?
Food Safety and Food Security. Introduction to the Sorption of Chemical Constituents in Soils. Pests and Pollinators. Soil erosion controls on biogeochemical cycling of carbon and nitrogen. The Influence of Soils on Human Health. Use and Impact of Bt Maize. Aquaculture: Challenges and Promise.
Soil Carbon Storage. Soil Minerals and Plant Nutrition. Soil Water Dynamics. The Conservation of Cultivated Plants. The Soil Biota. Transgenic Animals in Agriculture. Aa Aa Aa. History and Key Concepts. Figure 1. Sustainable agriculture gives equal weight to environmental, social, and economic concerns in agriculture. Sustainable Agriculture and the Management of Natural Resources.
Figure 2. A clover and grass cover crop adds biodiversity to an almond orchard, which aids in nutrient cycling and provides habitat for beneficial insects, while also building soil organic matter. Figure 4.
Sustainable Agriculture and Society. Agroecosystems cannot be sustainable in the long run without the knowledge, technical competence, and skilled labor needed to manage them effectively. Given the constantly changing and locality-specific nature of agriculture, sustainability requires a diverse and adaptive knowledge base, utilizing both formal, experimental science and farmers' own on-the-ground local knowledge.
Social institutions that promote education of both farmers and scientists, encourage innovation, and promote farmer-researcher partnerships can increase agricultural productivity as well as long-term sustainability Figure 4. A farmer field school in the Democratic Republic of Congo encourages farmers to learn about sustainable farming practices from visiting teachers as well as from each other's on-the-ground experiences.
Figure 5. Instruction in school gardens and other public gardens helps children and their families learn to grow fruits and vegetables around their own homes or in community garden plots. Social, economic, and environmental sustainability are closely intertwined and necessary components for a truly sustainable agriculture.
For example, farmers faced with poverty are often forced to mine natural resources like soil fertility to make ends meet, even though environmental degradation may hurt their livelihoods in the long run. Only by creating policies that integrate social, environmental, and economic interests can societies promote more sustainable agricultural systems. Ecozone - a broad geographic area encompassing a distinctive pattern of climate conditions, type of landscape, and species of plants and animals.
Resilience - Ability to rebound or recover from adversity. In the context of an agroecosystem or food system, it is the ability of that system to remain viable when affected by adverse forces, such as pest infestations, environmental degradation, economic downturns, etc. References and Recommended Reading Altieri, M. Millions of people still depend on traditional bioenergy like wood or charcoal for cooking and heating, which can be unsustainable and pose health risks.
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In many developed countries, the rising costs of fossil fuels , as well as concerns about energy security and climate change , are generating new interest in other forms of bioenergy. For example, new liquid biofuels are made from crops or from agricultural and forestry residues. However, energy is needed to grow, transport and process bioenergy crops, causing considerable debate about their net benefit in terms of greenhouse gas reduction.
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Another major concern is that using crop land to produce fuel could raise food prices, drive small-scale farmers off their land and prolong hunger in the world.
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