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Item mexico slash burn labour 7665 444 tools machines

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Unformatted text preview: Less needed, supplied by irrigation & fertilizer • Less needed, protection conferred by insecticides & fungicides 19 20 5 3/25/2013 Energy budgets for 2 styles of maize production (kcal x 102; Pimentel, Cornell) Crop type annual wheat versus perennial wheat: which is better? Item Mexico slash & burn Labour 7665 444 Tools, machines 166 1300 Seeds Inputs Big root systems can scavenge scarce H2O & NPK, don’t need them provided. Shed roots enrich soil. Lack of tillage prevents erosion. USA mechanized 468 540 Fuel 1270 N fertilizer 2400 P fertilizer 227 K fertilizer 155 Lime 135 Pesticides 1100 Drying grain 800 Electricity 100 Transport Output Grain 97 1944 kg 8000 kg 21 22 - Comparing output and input shows us that we must supply a LOT of input to generate these high outputs -There is a significant cost to this type of production -Note that the input in the Mexican Slash & Burn style of f arming does not even COMPARE to the input in mechanized f arming -Perennial versions of today's grain crops could be developed -These versions could make agriculture more sustainable -These crops would not require tilling of the soil each year -This will reduce the loss of soil and degradation -Perennial plants provide protection to the soil :) Modern agriculture depends on energy subsidies Economic & political implications • Energy content of cornflakes used to be solar • Now it includes much gasoline, diesel, natural gas, hydro, coal, nukes • The crowning absurdity: now replacing gasoline with ethanol from corn because of quirky American politics 23 -Use oil to fertilize corn -> har vest corn -> use it to power cars in p lace of gas -> MAKES NO SENSE! • Cost of food tied to cost of petroleum & electricity • China and India subsidize costs of N fertilizer to farmers • With current technology, increasing food supply requires burning more fuel and clearing more land 24 -This is a basic problem that we're having -We have exhausted our resources that make agriculture a good s olution to increasing food supply, but we have not found a p ermanent solution that is SUSTAINABLE 6 3/25/2013 How sustainable is modern, high intensity agriculture? • Petroleum subsidies are huge (replaced sunlight by oil) • Water requirements huge but supplies limited, running out in some places • Fertilizer (N expensive, P&K limited) • Irrigation often damages soil • Soil erosion • All of these will interact with climate change 25 7...
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