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Industrial Agriculture in the US

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Increase yield at lower cost MAKE A LIVING!

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Best available ways to do this: Fertilizers and pesticides Petrochemical Chemical derived from petroleum or natural gas Industrial equipment E.g. combine: Combines tasks of harvesting, threshing, cleaning grain crops Waterworks Irrigation Drainage

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Initially monumental, then decreased: applying one ton of fertilizer gave average yield of: 1980: 15-20 tons corn 1997: 5-10 tons corn 1910-1983: US corn yields increased 346%. Energy consumption for agriculture increased 810%. Costs increased.

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1. Increased erosion 2. Salinization 3. Fertilizer and pesticide effects 4. Reduction in soil biodiversity

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Peter Warshall (biologist, anthropologist): Many farmers and soil scientists are rejecting the ag-industrial paradigm and embracing a more holistic understanding of soil as irreplaceable, multigenerational natural capital

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Plowing is a necessary evil Have to turn the sod to make it produce To put in seed To allow roots to penetrate To allow water to infiltrate To air out pathogens and allow microbes to decompose To stir up nutrients To reduce weeds Plowing leads to loss of topsoil inevitable

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You tell me!

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Higher prices for crops have been correlated with more erosion. Why? Higher prices for soy/wheat/corn Stimulate hope for more income More farming of marginal land More erosion Also, farmers receive greater government payments for growing high erosion-making monocrops.

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1937: government spent $460 million ($5.3 billion by todays terms) 2000: spending $2.1 billion

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at 40% of US farmland

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Make it worthwhile economically (incentive) for farmers to use conservation methods such as no-till. Create conservation tillage methods that are not heavily chemically dependent. Too expensive for farmer and for soil/water health

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What is it? Soluble salts accumulate in soil, damaging roots Soluble salts can be removed by leaching NOT by evaporation. WHY? Irrigation water contains salts. Arid, semi-arid

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Good irrigation water: 0.3 kg salts m -3 Apply 10,000 mm water per season Adds 3000 kg salts per hectare per year Crops extract water; leave salt behind. Input must not exceed removal rate.

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Need to apply more water than will evaporate BUT without raising water table leaching requirement: the fraction of irrigation water that must be percolated from root zone to prevent salinity A tricky business!

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Additional problem: Where do the leached salts go? To drains; to water supply

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Leaching of excess nutrients into water Microbial resistance to pesticides Loss of organic matter Petroleum dependence

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Haber process of nitrogen production Mining of phosphate and potash Add necessary nutrients to soil Less dependence natural fertility Organic matter maintenance loses critical importance

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Green Revolution allowed fewer farmers to manage more cropland Thanks to fertilizers and pesticides Lost need to manage diverse crop systems Could purchase fertility

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Diminished role of nitrogen-fixers Amplified role of nitrogen-feeders Speeds up decomposition Decrease of OM changes structure : erosion Loss of humus: less water-and air holding capacity More irrigation required Less O, slows aerobic respiration Cumulative effect: fewer available nutrients Apply more fertilizer!!

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Mississippi drains 1.2 mill mi 2 Eroded soils, excess nutrients from fertilizers Dead zone (size of Connecticut): Only algae only can live! Nitrogen excess; oxygen depletion (only 18% of N applied to fields is taken up by plants)

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Agriculture is largest non-point source of pollution in US. Nitrites in water supply: blue baby syndrome

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Haber process: extremely energy-costly Consumes more energy than any other aspect of agriculture 2200 pounds coal produce 5.5 pounds usable nitrogen Energy required for machinery, pumps, fertilizers, factories, transportation, seed varnishes, transportation

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1970s began using plastic sheeting to increase temps, reduce evaporation Seeds coated with bacteria, limestone, P powder, Seed coating water-soluble adhesives Fertilizer granules coated with plastic to slow release of nutrients

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Food miles Before reaching table, most American food moves >1300 mi from soils it grew in. Most American farm soils contain seeds, minerals and petrochemical additives harvested 100s-1000s of miles from the farm.

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Water from dammed rivers travels 100s of miles by aqueduct to irrigate arid, semi-arid soils Draining soils 110 million acres drained Fertilizers carried in drains downstream MN River basin: 40% soils are drained Fertilizer goes to Miss.

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Jason McKenney (owner and grower for Pursimma Greens, organic farm, CSA) Plants are far from simple machines with simple needs. To understand them as such is to abuse them and, in turn, to deprive ourselves of the nutrition and taste that we may derive from them.

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Complex web of biological activity roots, microorganisms, macroorganisms Provide services for agroecosystems: nutrient recycling regulate soil organic matter change structure, water regimes enhance acquisition of nutrients by plants

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Agricultural practices must: Supply organic matter Variety of niches of organisms; need variety of OM Diverse crops (intercropping, multicropping) Protect habitat ( aeration, temperature, moisture, nutrients) Reduce compaction, chemicals, minimal tilling

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Pay attention to: Soil ecosystem Productive capacity Agro-ecosystem health