Effect of Different Forms and Levels of Urea Fertilizer on Rice (Oryza sativa L) and Mineral Nitrogen Status in Soil

Abstract

Field experiment was conducted to determine the effect of prilled urea (PU) and urea super granule (USG) with their different nitrogen levels N1: 70, N2: 100 (recommended dose) and N3: 130% on rice and NH4+-N/NO3- -N in post-harvest soil. Experiment was laid out in a randomized completely block design with three replications at Bangladesh Institute of Nuclear Agriculture (BINA) Farm, Mymensingh, Bangladesh during 2015-16. Higher yield attributing characters (plant height, effective tiller panicle-1, panicle length were achieved from USG × N2 treatment. USG, N2 (100% N) and USG × N2 produced the highest grain (3.60, 3.64, 3.78 t ha-1) and straw yield (3.55, 3.45, 3.70 t ha-1) respectively. Though USG × N3 treatment produced the highest effective tiller, panicle length and unfilled grain but USG × N2 treatment produced maximum grain yield of rice due to higher filled grain. In respect of mineral nitrogen, Ammonium -N (NH4+-N) was decreased with the increase in soil depth but opposite result was found in nitrate-nitrogen (NO3- -N) in soil. Deep placement of USG fertilizer released NH4+-N slowly and steadily compared to prilled urea in soil. As a result, one time fertilizer application of USG is better than three times broadcast application of PU in terms of crop yield, nitrogen status in different depth of soil and labour cost. Future research needs to develop the effective USG fertilizer applicator for deep placement in soil during crop production.