Environmental Science and Sustainable Agriculture
Ecosystems and agricultural impacts
Ecology studies producers, consumers, decomposers, food chains, energy flow and nutrient cycles. Agriculture can cause soil erosion, salinization, groundwater depletion, pesticide pollution and greenhouse gas emissions, including methane from flooded rice and nitrous oxide from excess fertilizer. The exam tests these impacts and sustainable alternatives.
Sustainable practices
- Organic farming: FYM, compost, vermicompost, green manure, biofertilizers and biopesticides.
- Conservation agriculture: minimum tillage, residue retention and crop rotation.
- Water management: drip, sprinkler, rainwater harvesting and tank rehabilitation.
- Agroforestry, crop diversification, integrated pest management and integrated nutrient management.
Worked example
A farmer applies 10 t/ha of FYM containing 0.5% N and wants to supply 60 kg N/ha. Nitrogen from FYM = 10,000 kg × 0.005 = 50 kg. The remaining 10 kg N is supplied by urea: 10 ÷ 0.46 = 21.7 kg urea. The reasoning is to convert tonnes to kilograms, multiply by the nutrient percentage, subtract the organic contribution and divide by the fertilizer grade. Applying FYM well before sowing allows mineralization.
Traps that cost marks
Equating organic farming with zero inputs; assuming FYM nutrients are immediately available; ignoring methane from flooded rice; and treating sustainability as only environmental when it also includes economic and social dimensions.