Yield Response of Upland Rice as Influenced by Enhanced-Efficiency Nitrogen Fertilizers in the Brazilian Cerrado

Nitrogen (N) fertilizers have their use efficiency adversely affected by the rate and source of N. A two-year field experiment was conducted to examine the yield response of upland rice by using NBPT (urease inhibitor), PCU (polymer-coated urea) and uncoated urea under different N application rates. It was hypothesized that either NPBT or PCU may result in increased yield components of upland rice when compared to conventional urea. The experiment was set up in a randomized block design in a 3 × 4 + 1 factorial scheme, with four replicates. Treatments comprised three sources (conventional uncoated urea, NBPT-treated urea, and polymer-coated urea) and four rates (30, 60, 90 and 120 kg ha-1) of N, in addition to a control treatment (no fertilizer application). Nitrogen fertilizers were applied in two split doses: 50% at the seedling stage, and 50% at the tillering stage (~80 days after planting). The results revealed that the use of enhanced-efficiency N sources increased the productivity and plant height of upland rice crop when compared to conventional urea. As compared to when it is untreated or polymner-coated, treating urea with NBPT resulted in increased 100-grain weight.