NITROGEN MANAGEMENT AND FERTILIZER USE EFFICIENCY FOR LOWLAND RICE IN PAKISTAN

With a view to develop simpler techniques for improving the efficiency of nitrogen fertilizer use for lowland rice, field studies were conducted in 1986 and 1987. During 1986, dry soil incorporation of urea was compared with puddled soil application of urea and calcium ammonium nitrate (CAN) and deep placement of urea super granule (USG). In 1987, the application of urea in puddled soil without standing water (soil saturation) was compared with the application in standing water and deep placement of USG. The results revealed that deep placement of USG and dry soil incorporation of urea were comparable in their effect on the increase of the number of productive tillers, straw and paddy yield, and agronomic efficiency. Consequently N utilization and recovery efficiency were higher with these methods of fertilizer application than with the application of urea and CAN in puddled soil. Application of urea fertilizer under soil saturation conditions and deep placement of USG were found to be comparable in the production of tillers, straw and grain yield and both gave similar agronomic and N recovery efficiencies to the application of urea on the Miranpur soil under standing water conditions.