Water use efficiency of cotton as influenced by agro-environment

The water use (WU) and the water use efficiency (WUE) of crop under rainfed agriculture depends on the crop agro-environment in which it is grown. The present paper deals with the variation of WU and the WUE of rain-fed cotton in a black soil catena of central India in varying rainfall conditions. The studies reveal that both the WU and WUE vary with rainfall aberration. The average WU of cotton (var. H-4) varied from 327.3 to 401 mm and WUE from 3.30 to 4.34 kg ha⁻¹ mm⁻¹ in the soil catena. The lowest WU value was obtained for Lithic Haplustepts (P1) occurring on piedmont plain and the highest was observed for Vertic Haplustepts (P3) occurring on lower plain. The average WUE also followed the similar trend and showed a value of 3.30, 4.30, 4.88 and 4.34 kg ha⁻¹ mm⁻¹ for pedons P1, P2, P3 and P4, respectively. However, in the excessive rainfall year, on an average WUE decreased by 6.8 to 44.5 per cent over a normal year while the same, in the drought year, in general, increased by 1.5 to 10.6 per cent. The overall coefficient of WUE varied from 0.62 to 1.44 per cent. Over the years the lowest coefficient of variation of WUE was observed for P3 soil suggesting the most sustainability of Vertic Haplustepts (P3) for rainfed cotton production under varying rainfall situations.