Effects of Nitrification Inhibitor 3,4-Dimethylpyrazole Phosphate (DMPP) and Phosphorus (P) on the Yield and P Use Efficiency of Wheat

Low phosphorus use efficiency in calcareous soils is one of the problems of wheat production in the fields، all over the world. This experiment was conducted to elucidate the effects of nitrification inhibitor (NI) 3،4-dimethylpyrazole phosphate (DMPP) and phosphorus (P) levels on the yield and P use efficiency of wheat (Triticum aestivum L.). A factorial experiment in randomized complete block design was carried out with two factors of type of nitrogen fertilizer (1- control: with no added N fertilizer، 2 and 3- ammonium sulfate fertilizer (ASF) with and without nitrification inhibitor DMPP، 4 and 5- ammonium sulphate nitrate fertilizer (ASNF) with and without nitrification inhibitor DMPP with rate of 100 mg N Kg-1 soil) and different levels of P (0، 30، 60 and 90 mg P kg-1 soil) on spring wheat cv. Pishtaz during 2010 at ShahreKord University with three replicates. According to results، application of nitrification inhibitor DMPP with both of ASF and ASNF resulted to meaningful increase of soil available P at the end of experiment as well as significant increase of NH4+ and also significant decrease of NO3- in the soil during experiment as compared to similar treatments but without NI. The results indicated that application of nitrification inhibitor DMPP with ASNF at all P applied led to significant increase (P)