Combating Desertification through Integrated Use of Nutrient Resources in Arid Regions of Rajasthan

摘要

Low and erratic rainfall, high evaporative demand and less fertile soils severely restrict the crop production in arid ecosystems. Analysis of soil samples from >14000 villages of Western Rajasthan revealed that soils were universally deficient in organic carbon and nitrogen. About 47 and 43% villages were found low and medium in phosphorus and 2 and 40% in potash, respectively. Amongst the micronutrients, zinc and iron deficiencies were reported in 72.7 and 61.7% villageS Copper and manganese deficiencies also surfaced up in 10.8 and 11.6% villages, respectively. Crops respond favourably to fertiliser application but the magnitude depends on moisture availability during the season. For pearl millet 40 kg N in two splits and 20 kg P2O5/ha; while for legumes 20 kg N and 40 kg P2O5/ha appeared sufficient. Legumes responded significantly from 15-60 kg S/ha. Micronutrient application improved the yields by 15-31%. The average fertiliser consumption is very low due to uncertainty in crop production. The possible reasons being the risk due to weather aberrations mainly rainfall variability and extremely poor supporting soils. Indigenous nutrient sources like manures and inclusion of legumes in the cropping system are irreplaceable component of nutrient management strategy in arid system. Inoculation with non symbionts like Azospirillum brasiliense was found to contribute an amount equivalent to about 13 kg/ha of the N requirement of pearlmillet. Legumes like clusterbean and mothbean were found to fix about 20-40 kg N/ha with a residual effect equivalent to about 15-20 kg N/ha when inoculated with efficient strains of Rhizobium. Hence, integrated nutrient management strategy is the key to improve fertiliser use and minimizing risks in crop production in arid regions.