Dr. Hannah Krujia
ACTO Agronomy, KVK Phek
Agricultural crop residues are abundant both in kind and quantity however , most of them are wasted in the fields or ploughed back into the soil as conditioners and organic fertilizers and some are used as animal feed. A small quantity through bioconversion serves as raw material for traditional fermented food as well as substrate for mushroom cultivation. Crop residue, the largest product of agricultural harvests, contains large amounts of assimilated carbon (C) and nutrients such as nitrogen (N), phosphorus (P), and potassium (K). Crop residue management serve a double function, both confronting global warming and food security by increasing carbon sequestration in agriculture and increasing grain yields.
There are two different ways to manage crop residues. The first method is tillage prior planting when plant residues are incorporated into the soil. Another modern farming practice is reduced tillage or no-till farming, where crop residues are left on the surface and planting is carried out without soil tillage.
Crop Residue Incorporation into the Soil
The main purpose of ploughing crop residue is to improve soil organic matter. Ploughing at a depth of 20-30 cm together with adding of nitrogen fertilizers (Urea) enriches the soil with humus and also prevents nitrogen depression. Farmers who manage their fields with this practice, rely on the following crop residue advantages:
• Recycled nutrients removed by a growing crop • Maintained or increased soil organic matter that provides a substrate for soil microorganisms and increases the organic component of the soil • Better absorption of rain drops that decreases erosion potential.
In addition to the ploughing of crop residue, a farmer can also include cover crops i.e. green manure. It enriches the soil with organic matter, improves its biological activity, provides better accessibility of nutrients, and enables biological water drainage on heavier soils. It also has a favourable impact on both heavy and sandy soils. Crop Residue - No-till Management No-till is a modern farm practice, the practice is based on leaving the crop residue on the field and the sowing of new crops directly into the untilled soil. No-till farming requires different practices to preserve higher yields, such as cover crops and fertilization and pesticide use, to achieve better soil properties. No-till farming has also many advantages on the soil:• Crop residue on the soil surface are responsible for cooling the soil, increasing the soil moisture and limiting evaporation, it also protects the soil from erosion and serves as a source of carbon • Heavy machinery passes are reduced, no-till farming uses only a sowing machine, thus preventing soil compaction and surface crusting. This makes it easier for plants to sprout and grow deep roots. Therefore, it results in reduced disturbance to the soil. • Farming costs such as labour, machinery costs, and fuel are reduced.
The main aim of no till farming is to move as little soil as possible in order not to bring weed seeds to the surface and not to stimulate them to germinate. The residues from the previous crops will remain largely undisturbed at the soil surface as mulch. Importance of crop residue management in Rainfed Agriculture 1. Crop residue management helps in controlling loss of water through runoff. 2. It increases infiltration and decreases evaporation of water. 3. It controls weeds, soil temperature through radiation shielding. 4. It adds soil nutrients through organic matter. 5. It improves mineral solubility soil structure, soil biological regimes through organic matter addition.