Cover crop is grown to improve and protect the soil not to standing harvest. Cover crop has the capability to control erosion and weeds, to improve soil tilt and to maintain soil organic substances. Cover crops reduce compaction. It has been proved that these increase the water infiltration that decreases gradually because of continuous sowing of main crops. Cover crops, also known as green manure crops, recycle and retain the plant nutrients during the gap period. These also provide habitat for much needed microorganisms. So advantages of cover crops are many but to get the proven advantages of this new farming technique, we need to manage green manure crops in professional manner.
The farmers, who use cover crop just to increase soil organic substance, may be frustrated. The primary reason is that high temperatures, short or high rainfall, excessive winters may cause rapid decay of cover crop. The contribution of cover crop to organic matter depends upon various determinants including growth rate of cover crop, left amount on the surface and percentage of removed crop etc. The C:N ratio of residues plowed down is also very important because cover crops with low C:N ratio break more rapidly. Experts suggest that to make certain trade-offs between the practices adopted to maximize the growth of cover crop and the practices to maximize marketable yield of vegetable crop.
Generally
cover crops consist of mixtures of grasses and legumes. Grass oriented green manure crops do germinate quickly and grows fast even in the fall to protect the soil from low temperature. However, such green manure crops dont fix nitrogen permanently but tie up the soil nitrogen temporarily, when these are ploughed down. Legumes grow comparatively slow during the fall but grow fast during spring season. These provide good amount of nitrogen and biomass for summer season vegetable crop.
During the Fall season, grains can be used as catch crops to retain the nutrients from previous crop. Addition of fertilizer or other supplements are necessary for optimum growth rate. Phosphorus application significantly increases the yields of subterranean and white clovers. Higher nitrogen content is found in the plants treated with phosphorus.
To get the proven benefits of cover crops for long time, selection should be made in accordance to the local weather conditions in particular season.
