Fertilisers are commercially produced plant nutrients, which supplynitrogen (N), phosphorus (P) and potassium (K) to the soil.
Urea, Ammonium sulphate, Superphosphate, potash, NPK (Nitrogen, Phosphorus, Potassium).
Spraying fertilisers
Advantages of fertilisers:
  • Easily available, easy to use and store.
  • Produces higher yields of crop that is equivalent to high-cost farming.
  • Ensures good vegetative growth (leaves, branches and flowers) that gives rise to healthy plants.
Disadvantages of fertilisers:
  • Need to be applied carefully in terms of proper dose, time, and after the pre and post-application precautions for complete utilisation. For example, fertilisers cause water pollution when they get washed away when the plants do not fully absorb them due to excessive irrigation.
  • Continuous use of fertilisers in an area destroys soil fertility as the organic matter present in the soil is not replenished. Thus, microorganisms in the soil are harmed.
  • Fertilisers provide only short-term benefits.
Thus, to maintain soil fertility, short term benefits of using fertilisers and long-term benefits of using manure are considered to aim at optimum yields in crop production.
Organic farming:
Environment-friendly farming system with minimal or no use of fertilisers, herbicides, pesticides etc. Organic manures, recycled farm-wastes (straw and livestock excreta) are used maximum. Healthy cropping systems [mixed cropping, inter-cropping and crop rotation] are beneficial in insect, pest and weed control besides providing nutrients. The organic matter used in organic farming includes:
  • Manure
  • Bio-fertilisers formed by the use of bio-agents like a culture of blue-green algae, Rhizobium in legumes.
  • For grain storage purposes, neem leaves or turmeric are used as bio-pesticides.
Organic fertilisers
Leguminous crops that include the pulses - cowpea, pigeon pea, peas, chickpeas (gram), and the soya bean contain nitrogen-fixing bacteria in their root nodules
Rhizobium in root nodules
These nitrogen-fixing bacteria fixes nitrogen  in the soil which is usable (converts atmospheric nitrogen to soluble nitrogenous compounds - ammonia). Examples of nitrogen-fixing bacteria include rhizobium. Thus, leguminous plants does not need nitrogenous fertilisers.