Improvements in the physical and chemical characteristics of degraded soils supplemented with organic–inorganic amendments in the Himalayan region of Kashmir, Pakistan

Efficient use of organic amendments and changing cropping pattern are important management strategies for restoring the degraded upland soils of Himalayan region. This study was conducted to determine the quantitative effect of poultry manure (PM) and wheat straw residues (WSR) repetitively applied alone or in combination with urea N (UN) on physical and chemical properties of soil under wheat–soybean cropping sequence over three years (2008–09, 2009–10, 2010–11). Treatments included PM100, WSR100, PM50 + WSR50, UN100, UN50 + PM50, UN50 + WSR50, UN50 + PM25 + WSR25 and a control. Added amendments were applied on N equivalent basis at the rate of 100 kg N ha− 1. Results indicated that organic amendments applied alone or in combination with UN significantly improved soil physical characteristics by lowering bulk density 7–12%, penetration resistance 3–4% and increasing hydraulic conductivity 15–32%, and aggregate stability 13–35%. Application of UN100 alone was ineffective in improving any of these characteristics. Combination of organic–inorganic amendments increased soil organic matter content by 3–9%, total N 14–29%, available P 5–35% and extractable K 12–39%. Response of micronutrient to organic or organic–inorganic amendments was even higher than that recorded for macronutrients. Organic amendments increased soil pH while UN displayed acidifying effect. The C sequestration and nutrient pool of the soil amended with WSR remained rich over PM even though PM contains a lot more nutrients. The study clearly demonstrated that organic amendments applied alone or combined with UN improved the physical characteristic and fertility status of the soils and may be considered as a useful management strategy for restoration of degraded soils in the mountain ecosystem of the Himalayan region of Kashmir, Pakistan.