Elements of sustainable agriculture

What sustainable agriculture means

Sustainable agriculture produces enough food today while keeping soil, water and biodiversity healthy for the future, and keeping farmers economically secure. It relies on natural processes and local resources instead of heavy external chemicals.

Main elements

• Mixed farming: combining crops with livestock. Animal dung becomes manure and crop residues become fodder, so nutrients cycle within the farm. (Do not confuse with mixed cropping, which is growing two or more crops together on the same land.)
• Crop rotation: growing different crops one after another on the same field, for example a cereal followed by a legume. Legume roots carry Rhizobium bacteria in nodules that fix atmospheric nitrogen, restoring soil fertility. Rotation also breaks pest and disease cycles.
• Organic inputs: farmyard manure, compost, vermicompost, green manure (crops such as sunn hemp and dhaincha ploughed into the soil) and biofertilisers: Rhizobium, free-living Azotobacter and Azospirillum, blue-green algae (Anabaena, Nostoc) in paddy, the Azolla–Anabaena association, and mycorrhizal fungi that help roots absorb phosphorus.
• Biopesticides: living organisms or natural products that control pests, such as Bacillus thuringiensis (Bt) against caterpillars, the fungus Trichoderma against soil-borne diseases, nuclear polyhedrosis viruses, neem-based products and the egg parasite Trichogramma.

Integrated Pest Management (IPM)

IPM keeps pests below the economic threshold level (the pest level at which control costs less than the damage) using several methods together: cultural (resistant varieties, rotation, clean fields), mechanical (hand-picking, light and pheromone traps), biological (predators, parasites, biopesticides) and, only as a last resort, careful use of chemical pesticides. The aim is control, not total elimination.

Key points

• Legumes add nitrogen via Rhizobium root nodules.
• Bt, Trichoderma, NPV and Trichogramma are biological controls.
• IPM uses chemicals only when pests cross the economic threshold.
• Mixed farming = crops + livestock; mixed cropping = two crops together.

Exam tips

• Match each organism to its role: Rhizobium (N-fixation in legumes), Azolla (paddy), Trichoderma (fungal biocontrol), Bt (insect larvae).
• For "which is NOT a part of IPM" questions, look for routine calendar spraying.