Saturday, 15 July 2006
153-46

Soil–crop Response under Wastewater Irrigation: A Case Study in Sub-Humid Orissa.

Madhumita Das, R. B. Singhandhupe, K. Kanan, E. Antony, and H. Chakrabarty. Water Technology Centre for Eastern Region, Chandrasekharpur,, Orissa, Bhubaneswar, 751 023, India

Rapid degradation of soil, shrinking land mass and depletion of fresh water reserve are the major impediments of agriculture nevertheless to feed the billions it needs to prosper both in terms of quantity and quality of produce. The whole country is reeling under water scarcity though for achieving the target food production, expansion of irrigated agriculture is a prerequisite especially in India. Hence making use of marginal sources like sewage, industrial effluent, drainage, or run ¨C off water in irrigation subject to securing soil and water qualities, is appropriate and also inevitable for developing countries. The pulp and paper mill is one of the major effluent generating industry in the world. The prospect of utilizing paper mill effluent in irrigation was explored in this study. Laboratory experiment on the influence of Emami Paper mill effluent (a newsprint manufacturing unit in Eastern India) application revealed that the germination percentage of maize (Zea mays) in vitro was decreased with increasing effluent concentration. But low rate of root inhibition enhanced vigour index and thus signaling its possibility of survival in situ. The effluent was rich in Ca (22.56), Mg (5.13), and dissolved organic matter (50.0) in mgl-1, neutral in reaction (pH 7.21) and had low salt content. The field experiment in succession on a Ca deficient (4.02 mg kg-1), low P (1.38 mg kg-1), sandy loam, non ¨C saline soil (belongs to Aeric Haplaquepts) was carried out by growing maize (variety DHM 103) in 2002-03 and 2003-04 at Baleswar of Orissa a state in sub-humid region of eastern India. Orissa though belongs to high rainfall zone (1482 mm) suffers by water scarcity during post and pre ¨C monsoon periods. Among crop growth parameters the leaf area index and plant height at knee high stage were greatly influenced @ 32 to 33 and 4 to 28% due to effluent irrigation while the effect on cob length/girth/weight was marginal. No influence was also evident in grain and stover yield rather the grain yield was improved by 3 to 6 % in second year. The other yield attributing characters like grain no. per plant was also magnified by 19 to 29%; grain to cob weight ratio from 1.2 to 11% under effluent irrigation over the corresponding values under 'fresh water irrigation' kept as normal practice. The N concentration at knee high stage was reduced to the tune of 1.23 to 2.04 times in first year, while P, K and Ca concentrations were accelerated by 1.10 to 1.47, 1.02 to 1.09 and 1.93 to 3.07 times respectively under effluent irrigation over fresh water. Similarly the Ca concentration was also enhanced (1.6 to 3.81) followed by N (1.21 to 1.32) and P (1.08 to 1.11 times) in second year without marinating any consistent trend with effluent concentration in general. Nutrients' concentration was also augmented over fresh water irrigation in the order of Mg (1.39 to 1.83) > P (1.36 to 1.77) > Ca (1.1 to 1.77) > K (1.07 to 1.29 times) in stover while in total nutrient uptake Mg preceded K °Ô P > Ca > N. Irrespective of effluent concentration the important soil parameters were improved under effluent irrigation. The magnitude of response was 1.18 to 1.34 times increase in organic carbon, 1.22, 1.21, 1.09, and 1.8 times in humus carbon, available P, K and N concentrations at harvest. The exchangeable Ca and Mg contents of soil were also modified by 1.03 to 1.04 and 1.3 to 1.74 times over fresh water irrigation. However no carry over effect of the first year experiment was noticed either in soil parameters or in crop yield attributes. Thus by ensuring soil and crop qualities in continuum, the study suggests that paper mill effluent can be utilized for irrigating acidic non saline soil under decreasing availability of fresh water resources. This also helps to solve the problem of waste disposal to some extent and conserve fresh water for other use as well.

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