27. Optimizing surface soil NPK balance through integrated nutrient management in wheat-soybean cropping system from Rawalakot Pakistan

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Abdul Khaliq, Mohsin Zafar, Muhammad Kaleem Abbasi, Majid Mahmood Tahir Sair Sarwar


The efficient use of organic-inorganic amendments and changing cropping pattern are important management strategies to improve crop productivity as well as restore the nutrient buildup of degraded soils. A three-year (2008–09 to 2010–11) soybean-wheat rotation field experiment was conducted at Rawalakot, Azad Jammu and Kashmir. Treatments included PM100, WSR100, PM50+WSR50, UN100, UN50+PM50, UN50+WSR50, UN50+PM25+WSR25 and a control (unfertilized). Applications of amendments were made on N-equivalent basis at the rate of 100 kg N ha-1. Data on surface NPK balance showed a net depletion of 41.2 kg N ha-1year-1 and gain of 95.8 and 16.5 kg ha-1year-1 of phosphorus (P) and potassium (K) for the control soil during three years. Soil amended with either organic amendments (PM and WSR) and UN alone or combination of both organic amendments + UN yielded positive surface N and P balance that varied between 40.7-86.8 and 84.5-213.7 kg ha-1year-1, respectively under different amendments. The UN100 and UN50+PM50 treatments showed a K deficit of 12 and17.1 kg ha-1year-1, respectively while UN50+WSR50 and UN50+PM25+WSR25 treatments marginally increased soil K content between 1.3-5.2 kg ha-1year-1compared to 16.5 kg ha-1year-1 in the control treatment. Treatments receiving repeated applications of poultry manure alone or with UN has the potential to improve the surface N and P balances. Therefore, it is recommended to increase annual addition of K fertilizer (beyond 50 kg K2O ha-1year-1) with organic-inorganic amendments to maintain K balance and sustain long-term soybean-wheat productivity of degraded soils of Himalayan Hindukush of Azad Jammu and Kashmir.

Keywords: Integrated fertilization; Nutrient balance; Surface soil; Wheat straw residue


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