RICE CULTURE Influence of Urea and Agrotain Applied to a Dry Clay Soil Several Days Prior to Flooding on the Grain Yield of Delayed-Flood Rice

Agrotain has shown in previous studies on silt loam soils to be much less prone to ammonia volatilization loss and to result in higher rice-grain yields compared to urea when the flood cannot be applied immediately after nitrogen (N) fertilizer application. However, no research has been conducted to determine if Agrotain is superior to urea as an N source for rice grown on clay soils, which volatilize urea as ammonia slower and to a lesser degree than silt loam soils. Thus, a 2-year study on clay soil was conducted comparing urea and Agrotain applied 1, 5, 7, and 10 days prior to flooding on rice-grain yield. In both years of the study, urea and Agrotain resulted in similar rice-grain yields when the two N fertilizer sources were applied 1 and 5 days prior to flooding. However, Agrotain resulted in higher rice-grain yields compared to urea when the N sources were applied to the clay soil 7 and/or 10 days prior to flooding.