133inhibitors. Indeed, nitrification inhibitors delay the microbial oxidation [conversion
of NH 4 + to nitrite (NO 2 −)] for some time (several weeks or months), and thus are
very useful to reduce the microbial nitrification and subsequent denitrification
(Weiske et al. 2001 ; Zerulla et al. 2001 ), in dryland agriculture. However, the effi-
cacy of nitrification inhibitors to block nitrification and leaching is governed by
several factors such as rate, method and time of application of nitrification inhibitors
(Zaman and Blennerhassett 2010 ; Zaman and Nguyen 2012 ), crop type, crop geom-
etry, irrigation, method of application of NH 4 + based fertilizers (Sanz-Cobena et al.
2012 ), temperature, rainfall (Shepherd et al. 2012 ), soil pH, soil texture, soil mineral
N and soil organic carbon (Barth et al. 2001 ; Shepherd et al. 2012 ).
4 Conclusions
The productivity of dryland crops can be substantially enhanced with integrated
nutrient management techniques. The CA-bases cropping systems may be benefi-
cial to conserve soil moisture and nutrients within soil. Application of chemical
fertilizers should be on the basis of soil analysis. Besides chemical fertilizers, use of
green manures, organic manures and compost should be encouraged and subsidized.
The intercropping of legume and non-legume crops in dryland soils may be benefi-
cial to enhance/sustain the soil fertility. Cover cropping during the rainy season may
be useful to reduce the soil losses due to soil erosion. To reduce the loss of nutrients
through runoff and erosion, the land leveling, contouring and terracing may be ben-
eficial. Mulching should be done between crop rows to conserve the soil moisture
and modulate the soil temperature. Use of slow release fertilizers and nitrification
inhibitors may be another pragmatic option to improve the crop nutrition in dryland
crops. Use of biofertilizers such as azotobacter, rhizobium, azospirilium, blue green
algae, phosphate solubilizing organisms and vesicular arbuscular mycorrhiza may
be an integrated part of integrated nutrient management in dryland agriculture. In
dryland agriculture, the integrated plant nutrient management system necessities a
holistic approach to manage crop nutrition through judicious and combined use of
chemical fertilizers, organic manures (farmyard manure, compost, biogas slurry,
crop residues, green manures, vermi-compost), biofertilizers and growing of legu-
minous crops in crop rotation.
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