Nitrogen in Arid Soils: Availability and Integrated Management for Increased Pearl Millet Production

Abstract

The status of nitrogen in arid soils is generally low (0.021-0.056%), with amino acid-N and NO3-N the predominant organic and inorganic fractions. The content of NO3-N fluctuates seasonally, with surface accumulation during the summer and at lower depths during the rainy season. Nitrogen deficiency generally limits pearl millet yield. This deficiency can be corrected with fertilizer, but because of low fertilizer-use efficiency and lack of residual effect, the application of fertilizer considerably increases risk. Split application of fertilizers is the first step towards reducing risk. Other steps include (1) avoiding basal application of fertilizer to pearl millet if a legume has been grown in the preceding year; (2) use of farmyard manure and crop residues in conjunction with fertilizer N; and (3) incorporation of legumes in the cropping system. Growing of legumes alters the content of different fractions of organic N, promoting better pearl millet growth. Farmyard manure and crop residues also improve soil quality, albeit slowly.