How do I use FYM or compost properly and how much before sowing?

Farmyard manure and compost improve soil organic carbon, structure, water holding and the slow release of nutrients, but they only work well if they are properly decomposed and applied at the right time. Use well-rotted, dark, crumbly manure, not fresh raw dung, because fresh manure can tie up nitrogen as it breaks down, attract pests and carry weed seeds. The usual practice is to spread the FYM or compost in the field and incorporate it into the soil a few weeks before sowing, so it is mixed in and has time to settle and continue breaking down before the crop goes in. Spread it evenly rather than in lumps. Organic manure complements your chemical fertiliser; it does not instantly replace the full dose, but over years it raises organic carbon and can let you rely a little less on bagged fertiliser. For the quantity per acre and how to adjust your bagged fertiliser when you add good FYM, follow your KVK advice and your Soil Health Card or soil test, and do not over-apply either the manure or the fertiliser.