Nitrogen management and fertilizer use efficiency for lowland rice in Pakistan

Abstract

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.

Residual phosphorus and zinc influence wheat productivity under rice–wheat cropping system

“…The clayey, alkaline and calcareous nature of soils in Pakistan, Zn fertilizer is mainly fixed by soil particles and very low amount is available and uptake by rice crop plants (Tahir et al 1991 ) and so the residual Zn in soils could increase productivity of subsequent wheat crop under rice–wheat cropping system. Zia et al ( 1996 ) reported that residual effect of the higher rate of 10 kg Zn ha −1 was most beneficial to increase rice GY than the low rate of 5 kg Zn ha −1 under RWCS. Likewise, Hussain ( 2004 ) reported that the residual Zn (5 kg ha −1 ) increased the paddy GY by 6.1 %.…”

“…The major cause of low yield under RWCS is nutrients depletion from the soil (Dawe 2000 ; Shah et al 2011 ). The continuous RWCS for several decades has thus resulted in nutrients depletion and decline in yields (Zia et al 1996 ; Hobbs and Morris 1996 ; Dawe 2000 ; Duxbury 2000 ; Shah et al 2011 ).…”

Nitrogen Losses and Physiological Efficiency of Rice Influenced by Nitrogen Sources under Saline Soil Condition

“…Since, it is clear from the data, that minimum N losses were detected from mixture fertilization even at lower rate, which conclusively resulted in enhancing apparent nitrogen recovery. Zia et al (1992) have reported similar elucidations. On the basis of this study, it could thus be inferred that apparent nitrogen recovery and physiological efficiency of rice crop can be improved through the blended application of urea and ammonium sulphate (1:1) in the salt-affected soil.…”

“…There were number of reasons as to why physiological efficiency decreases under saline conditions. Many research workers (Hamid and Ahmad, 1987;Aslam et al, 1989;Zia et al, 1992Zia et al, , 1998 have documented similar conclusions. From the results, it is clear that efficiency of N fertilizer was maximum when N was applied as a mixture of urea and ammonium sulphate at both the rates (600 and/or 800 mg N potG 1 ).…”

“…At this salinity level, pots fertilized with high dose of N had significantly higher N concentration as compared to lower dose, except mixture fertilization at 600 mg N potG 1 that was statistically similar to higher dose of mixture (800 mg N potG 1 ). The maximum concentration of 4.99, 4.98 and 4.97 g potG 1 was observed in the case of F6, F4 and F5 respectively which might be due to more N application and reduced volatilization losses through blended fertilization (De Datta et al, 1987;Hamid and Ahmad, 1988;Zia et al, 1992). N concentration decreased by about 11% with increasing soil salinity to 10 dS mG 1 .…”