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 October) is common phenomenon in Tarai (foothills of the Himalaya) of Uttar Pradesh, India. Puddled rice (Oryza sativa L.) crop followed by conventional land preparation for the succeeding wheat (Triticum aestivum L.) crop is normal cultivation practice in the region. This shallow water table can be effectively utilised to avoid puddling operations for the seeding of rice and reduce the degree of tillage required for the following wheat crop. An investigation was made in silty clay loam (Chernozem), for two consecutive years (1992-1993 and 1993-1994) at Pantnagar, India, in a rice-wheat cropping system. The treatments for rice were puddling and non-puddling with two fertility levels (NPK: 120:40:40 and 180:60:60) and for wheat two tillage systems (conventional and zero tillage) in puddled and non-puddled rice field with 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 non-puddling, whereas it was significantly higher after harvest. The hydraulic 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. Infiltration 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 enhanced the root length density by 12% but affected adversely the wheat crop and minimised the root length density by 28%. Both puddling. and non-puddling were found to be equally effective for grain yield of rice. However, non-puddling of rice produced significantly higher wheat grain yield than that of wheat followed by puddled rice. Conventional tillage of wheat produced significantly higher (25%) grain yield than that of zero tillage. This study indicated that in shallow water table conditions, direct drilling of rice in place of puddled rice and conventional tillage for wheat is an alternative cultivation practice in a rice-wheat system. (C) 2000 Published by Elsevier Science B.V. All rights reserved.