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Environmental Effects of Agriculture

Environmental Effects of Agriculture. (Non-point Source Pollution). Introduction. Agriculture generally behind the times (1990 –> USDA decided that water quality is a problem in the US - doh!) Can cause severe environmental impacts

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Environmental Effects of Agriculture

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  1. Environmental Effects of Agriculture (Non-point Source Pollution)

  2. Introduction • Agriculture generally behind the times (1990 –> USDA decided that water quality is a problem in the US - doh!) • Can cause severe environmental impacts • Agro-pollution hard to address – farming historically seen as stewardship of the land (actually stewardship of farmland)

  3. Why agriculture? • The Need to Feed • Unpredictable services offered by unmanaged system (natural environment) • Agriculture = managing environment

  4. Pollution from Agriculture • Agriculture often considered a life-style AR is a large exporter of pollution – Gulf of Mexico • Agriculture is hardest non-point source problem to solve • Only significant progress  pesticides (but not a big problem anyway)

  5. The Process of Agriculture • Crop selection 1. based on high yield and market need (exception – dairy farmer growing corn for cattle) 2. 350,000 spp. of terrestrial plants , < 2,000 ever cultivated or used for food 3. Wheat, corn, rice meets most of worlds caloric needs 4. US uses only about 25 crops -> low exploitation of plant resources

  6. The Process of Agriculture (con’t) • Propagation • Tillage – prepare soil to receive crop 2. Nutrient management

  7. The Process of Agriculture (Con’t) C. Protection Pest management Note: pesticides synthesized to kill, then quickly breakdown into “harmless” residues

  8. III. Modern Production Agriculture • Use of energy in agriculture to increase yield 1. Agriculture is an extremely E. intensive (HO Table 18.2) 2. Ways to save E. in agriculture a. Better herbicides (more specific) b. Better irrigation (polypipe) c. Alternative N2 inputs d. Fuel (avg fruit travels 1,300 miles to market  increase regional markets

  9. Modern Production Agriculture (con’t) B. Other factors affecting yield 1. Environmental conditions (HO) a. Spring - increasing temp, water needs b. Summer – need 25% light for max. Ps Note: often water stressed  get decr. in mass because using stored E. to survive c. Fall – plants start to die  harvest just before

  10. Modern Production Agriculture (con’t) B. Other factors affecting yield (con’t) 2. Manipulation by farmer a. tillage (plowing) manipulates soil, air, water b. altered nutrient cycles - bury dead organic matter - “ weed seed bank deep so no germinate - fertilization  N, P, K

  11. Modern Production Agriculture (con’t) C. Chemical fertilization 1. Forms of chemical fertilizers • Nitrogen (N) NH4NO3 (ammonium nitrate) – cheap but explosive NaNO3 (sodium nitrate) good but expensive CO(NH2)2 (urea) expensive, effective but may scorch NH3.H2O (anhydrous ammonia) cheaper, high loss by leaching NH4.OH (aqueous ammonia) less cheap, less “ “ “

  12. Modern Production Agriculture (con’t) 2. Phosphorous (P) Phosphate rock – grind into powder, cheap but very water insoluble CaH2PO4 (superphosphate) together make up Ca(H2PO4 )2 ( “ ) 50% of all P used H2P2O4 (phosphoric Usually extract from rock, H3PO4 acid) treat with H2SO4 use

  13. Modern Production Agriculture (con’t) 3. Potassium (K) KCl (potassium chloride) – most widely used K fertilizer K2SO4 (pot. sulfate) – expensive, but S has some fertilizer value K2NO3 (pot. nitrate) – expen, mainly used for vegetables Potash (K-oxide) – v. good for certain crops (potatoes)

  14. Modern Production Agriculture (con’t) 2. Ratio and Use of Fertilizers N : P : K 10 : 10 : 10 <-- % by weight Above is very soluble to increase movement into plants but also increases runoff OH

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