Manures and fertilisers are added to fields mainly to replenish minerals, which get depleted due to withdrawal by crop plants and reaching down to lower strata of soil.
1. Manures add a small quantity of all minerals to the soil. They improve soil hydration, soil aeration and activity of soil micro-organisms, some of which are required for solubilisation of heavy minerals.
2. Fertilisers are nutrient specific which contain one or more minerals in concentrated form. They meet the immediate and complete minerals requirement of high yielding varieties. However, they harm soil structure and cause pollution of crops, soil, groundwater and nearby surface water. A combination of both manure and fertilizer is highly useful.
