Nitrogen management in wheat sown in rice straw as mulch in North West India

摘要

Burning of rice straw after rice harvest in the Rice Wheat System of North west India can be overcome by sowing wheat into rice straw with the help of a machine called the 'Happy Seeder'. The adoption of zero tillage and retaining rice straw on the soil surface alters the nitrogen demand of the wheat crop due to changes in soil temperature and soil moisture under rice straw mulch, which in turn affects microbial growth. The microbes can either immobilise nitrogen or mineralise it and thus affects theplant growth. A field experiment was conducted to optimise the management of N fertilizer for wheat production under rice straw mulch so as to ensure high grain yield, high N use efficiency. Whilst band placement of nitrogen fertiliser at 180 kg/ha resulted in higher grain yield when rice straw was burnt, banding was not effective in increasing yield when straw was retained. The retention of rice straw as a mulch also resulted in higher mineral N concentrations remaining in the soil after harvest whichmay be used by subsequent crops in leaching can be minimised. This work provides evidence that retention of rice straw is not detrimental to yield if N management is optimised.