Comparative Efficiency of Nitrogen Sources for Lowland Rice Production

ABSTRACTRice (Oryza sativa L.) is the staple food for more than 50% world population and nitrogen (N) is one of the most yield-limiting nutrients for rice production worldwide. A greenhouse experiment was conducted to evaluate the efficiency of three N sources for lowland rice production. The N sources used were ammonium sulfate, common urea, and polymer-coated urea. There were three N rates, i.e. 100, 200, and 400 mg N kg−1 applied with three sources plus one control treatment (0 mg N kg−1). Growth, yield, and yield components were significantly increased either in a linear or quadratic fashion with the addition of N fertilizers in the range of 0–400 mg kg−1 soil. Maximum grain yield was obtained with the addition of ammonium sulfate at 100, 200, and 400 mg kg−1 of soil. Common urea and polymer-coated urea were more or less similar in grain production at 100 and 200 mg N kg−1. However, at 400 mg N kg−1 treatments, polymer-coated urea produced the lowest grain yield. Most of the growth and yield component...