Influence of nitrogen and weed management on the productivity of upland rice

Abstract

Nitrogen and weeds are two important factors that influence the productivity of rainfed upland rice (Oryza sativa L.) in tropical Asia. A low recovery of applied fertilizer N in rainfed uplands is generally associated with high nitrate leaching losses and weed interferences. Field experiments were conducted during the wet seasons of 2002 and 2003 at the research farm of Central Rainfed Upland Rice Research Station, Hazaribag, Jharkhand, India, to determine the response of upland rice to nitrogen applied at 60 kg N ha -1 as different forms of urea (single pre-plant application of controlled-release urea, single pre-plant application of urea supergranule and split application of prilled urea with or without basal N) against no N application under three weedcontrol regimes (unweeded, pre-emergence application of butachlor at 1.5 kg a.i. ha -1 supplemented with one single hand weeding or two hand weedings). The response of rice to applied N varied greatly among the three weed-control regimes. Across the different N treatments, the application of 60 kg N ha -1 resulted in a grain-yield increase above the unfertilized control of only 0.24 Mg ha -1 in unweeded treatments, whereas yields increased by 1.07 Mg ha -1 when butachlor application was supplemented with a single hand weeding and by 1.28 Mg ha -1 with two hand weedings. Among the weed-control measures, hand weeding twice produced highest grain yield in both years. The comparison of different forms of urea showed that a single pre-plant application of controlled-release urea resulted in average grain yields of 1.57 and 1.87 Mg ha -1 compared to 1.32 and 1.30 Mg ha -1 in the case of the recommended practice of split-applied prilled urea in the years 2002 and 2003, respectively. The highest agronomic N use efficiency of 15-20 kg grain per kg N applied and the highest apparent N recovery of 39%-45% were attained with controlled-release urea, suggesting that this N form is particularly beneficial for upland-rice cultivation under variable rainfall conditions, provided weeds are controlled.

Fertilization impacts on green leafy vegetables supplied with slow release nitrogen fertilizers

“…Nitrogen fertilizer benefit, namely agronomic nitrogen use efficiency (ANUE), was defined as the difference of vegetable yield between no fertilizer treatment and fertilization treatment per unit of supplied nitrogen (Singh et al, 2008). Nitrogen use efficiency was apparent nitrogen recovery efficiency (ANRE), which was defined as the difference of vegetable nitrogen uptake between no fertilizer treatment and fertilization treatment per unit of supplied nitrogen (Sinebo et al, 2004).…”

Effect of Crop Establishment Methods and Weed Management Practices on Productivity, Economics and Nutrient Uptake in Direct Seeded Rice (Oryza sativa L.).

“…DSR has a potential to replace the transplanted rice if weeds are controlled effectively. The yield loss due to poor weed management may vary from 10% to complete failure (Singh, 2005;Singh et al, 2008). The removal of competitive effect of weeds by weeding reduces inter-specific competition for resources more efficiently and enables the plants to utilize available resources more efficiently throughout the growth cycle, which in turn positively influences crop yield and biomass production.…”