Direct seeding of rice in the rice-wheat systems of the indo-gangetic plains and the implications for weed management

The rice-wheat rotation is the most widespread cropping system in the Indo-Gangetic plains from which the crop production is vital to the food security of India. Recent concerns about declining levels of productivity have focussed on the long-term sustainability of the system and, in particular, on the reliance of ground water for irrigation, the effects on soil structure of alternating wet and dry cultivations, and the increasing costs of labour. To address some of these concerns, studies were initiated to elucidate the effects of a number of different crop establishment and weed management methods on crop and weed growth. Researcher-managed, on-farm experiments compared rice growth after soil puddling and transplanting and direct seeding of rice using a zero tillage drill. Across 16 farm sites, grain yield was 10% lower after direct seeding compared to transplanting, but substantial savings in production costs accrue for the former. In a further experiment, weed growth at 28 days after sowing was greatest in the wet seeding treatments and least in the transplanted crop. Ischaemum rugosum and Fimbrislylis miliacea were significant weeds in the wet seeded and zero-tillage plots, though almost absent on the transplanted areas.