Improvement in Food Resources - Nutrient Management (Manure and Fertilizer)

Plants require 16 essential nutrients for growth. These are obtained from air, water, and soil. Air provides Carbon ($C$) and Oxygen ($O$); Water provides Hydrogen ($H$); and the soil provides the remaining 13 nutrients.

Nutrients are classified into two categories: Macronutrients, required in large quantities ($N, P, K, Ca, Mg, S$), and Micronutrients, required in very small quantities ($Fe, Mn, B, Zn, Cu, Mo, Cl$).

Manure is an organic substance prepared by the decomposition of animal excreta and plant waste. It is rich in organic matter (humus) but contains small amounts of nutrients.

Compost is prepared by the decomposition of livestock excreta and vegetable waste in pits. When earthworms are used to hasten this process, it is called Vermicompost.

Green Manure involves growing plants like sunnhemp or guar and then mulching them into the soil by ploughing. This enriches the soil specifically in Nitrogen ($N$) and Phosphorus ($P$).

Fertilizers are commercially produced plant nutrients. They provide Nitrogen ($N$), Phosphorus ($P$), and Potassium ($K$). While they ensure high yields, their excessive use can lead to water pollution and decrease soil fertility by destroying the organic matter and microorganisms.

Organic Farming is a system with minimal or no use of chemicals like fertilizers and pesticides, focusing on organic manures, recycled farm waste, and bio-agents.