Nitrogen fixation in nutrient management

Abstract

The rapid population increase per annum forces over-exploitation of natural resources, including soil. Both the sustainability of agricultural systems and environmental protection are of serious concern for most of the countries. As a result of rapidly increasing population, there is pressure on the limited soil resources. Intensified and diversified cropping per unit of land or time has depleted the soil fertility. One of the major factors limiting soil productivity on sustained basis is depletion of soil fertility. Due to low organic matter content in soil, the inherent nutrient supply capacity is poor. Moreover, the current jumping up prices of inorganic fertilizers and sometimes their non-availability could not withstand the fertilization demand of different crops. Ultimately, low yield is obtained even with the high intensity and diversity in the cropping system. Sustainability in the context of soil fertility can be obtained if the farmers should be able to operate within such a cycle that nutrients extracted from the soil should be returned back in order to avoid depletion leading to poor fertility and low yields, a real and immediate threat to food security and economic development. About 78% nitrogen is present in the air over every hectare of land, waiting to be trapped by legumes. Rates of symbiotic nitrogen fixation in legumes vary with plant species, cultivar, growing season, and soil fertility. Benefit of including legumes in crop rotation is that nitrogen fixed by them is almost as effective in promoting growth and development of plants as nitrogen applied as fertilizer.