Wheat yield, fertilizer N utilization and water use efficiency asinfluenced by tillage and P levels under rain-fed conditions

A field experiment was conducted to study the response of wheat totwo tillage treatments (tillage and no-tillage) and two P levels (30 and 60kg P ha-1) at farmer's field (Urmar) in Peshawar during 1998-2002. Theobjective was to improve the wheat yields through improved water andfertilizer management practices under the rain fed conditions. Tillagetreatment on the average did not improve the yield of wheat significantlybut application of phosphorus at 60 kg ha-1 improved the grain yield ofwheat in all growing seasons compared to 30 kg P ha-1. On the average,wheat crop utilized up to 37 percent of applied fertilizer N. The proportionof N derived from fertilizer (percent NdFF) by wheat was slightly higherin the tillage (27.3 percent) than in the no-tillage treatment (25.3 percent),and it was the case for the amount of fertilizer-N contributed to plant(14.6 kg ha-1 under tillage and 12.7 kg ha-1 under no-tillage). The percentNdFF by wheat was also higher at higher P level (27.2 percent) than atlow P level (25.5 percent). The wheat yields and N fertilizer utilizationduring 2000-2001 was relatively lower because of prolonged dry spelt overthe growing period. The percent N utilization from residual 15N labelledurea indicated that less than 1 percent of fertilizer N applied in previousyear was utilized by the following wheat crop. The tillage had improvedthe WUE of wheat grain (6.2 kg ha -1 mm-1) relative to the no-tillagetreatment (5.9 kg ha-1 mm-1). The P level at 60 kg ha-1 also resulted inhigher WUE (7.12 kg ha-1 mm-1) than at 30 kg ha-1(6.44 kg ha -1 mm-1).Over all higher water use efficiency was recorded during 1999-2000compared to 1998-99 although more rain was received during 1998-99.These results suggested that P fertilization was more important than thetillage treatment under the prevailing rain fed environment in Peshawarvalley.