Fast-growing crops ploughed back into the soil
Explanation
Green manuring is a sustainable agricultural practice aimed at improving soil fertility and structure. It involves the cultivation of specific fast-growing crops which are subsequently incorporated into the soil while they are still green and succulent, rather than being harvested for consumption.Analysis of Options:
- Manure derived from decomposed animal excreta is incorrect: Manure derived from decomposed animal excreta mixed with straw or bedding material is classified as Farmyard Manure (FYM).
- Organic matter processed by earthworms is incorrect: Organic matter that has been decomposed and processed by earthworms is known as Vermicompost.
- Fast-growing crops ploughed back into the soil is correct: Green Manure refers to plants (often legumes like Sunn hemp, Sesbania, or Cluster bean) that are sown and then ploughed back into the soil during their vegetative growth stage. This practice adds significant organic matter and nitrogen (via nitrogen fixation) to the soil, enhancing its physical and chemical properties.
- Synthetic fertilizers rich in nitrogen is incorrect: Synthetic fertilizers are chemically manufactured inorganic compounds (e.g., Urea, DAP), whereas green manure is a biological source of nutrients.
Key Takeaway: Green manure crops are cultivated specifically to be mulched into the soil to replenish organic matter and nitrogen, thereby preventing soil erosion and reducing dependence on chemical fertilizers.