Evaluation of non-puddling under shallow water tables and alternative tillage methods on soil and crop parameters in a rice-wheat system in Uttar Pradesh

The existence of a shallow water table (surface to 0.54 m from June to Octo ber) is common phenomenon in Tarai (foothills of the Himalaya) of Uttar Pra desh, India. Puddled rice (Oryza sativa L.) crop followed by conventional l and preparation for the succeeding wheat (Triticum aestivum L.) crop is nor mal cultivation practice in the region. This shallow water table can be eff ectively utilised to avoid puddling operations for the seeding of rice and reduce the degree of tillage required for the following wheat crop. An inve stigation was made in silty clay loam (Chernozem), for two consecutive year s (1992-1993 and 1993-1994) at Pantnagar, India, in a rice-wheat cropping s ystem. The treatments for rice were puddling and non-puddling with two fert ility levels (NPK: 120:40:40 and 180:60:60) and for wheat two tillage syste ms (conventional and zero tillage) in puddled and non-puddled rice field wi th two fertility levels. Puddling significantly reduced the bulk density of the surface (0-0.06 m) soil at the tillering stage of rice, compared to no n-puddling, whereas it was significantly higher after harvest. The hydrauli c conductivity of the 0-0.06 m soil depth also reduced to one-sixth and one -half due to puddling at tillering and harvesting stages, respectively. Inf iltration rate was decreased from 0.68 to 0.46 mm h(-1) at tillering and 1. 78 to 0.94 mm h(-1) at harvest due to puddling. The puddling only in rice e nhanced the root length density by 12% but affected adversely the wheat cro p and minimised the root length density by 28%. Both puddling. and non-pudd ling were found to be equally effective for grain yield of rice. However, n on-puddling of rice produced significantly higher wheat grain yield than th at of wheat followed by puddled rice. Conventional tillage of wheat produce d significantly higher (25%) grain yield than that of zero tillage. This st udy indicated that in shallow water table conditions, direct drilling of ri ce in place of puddled rice and conventional tillage for wheat is an altern ative cultivation practice in a rice-wheat system. (C) 2000 Published by El sevier Science B.V. All rights reserved.