Physical and Chemical Properties of Soil Near Cracks in Irrigated Vertisols Sown with Cotton-Wheat Rotations

Abstract

Properties of soil adjacent to cracks and in bulk soil were compared in furrow irrigated Vertisols sown to intensively tilled cotton (Gossypium hirsutumL.) followed by (fb.) minimum-tilled wheat (Triticum aestivumL.) in a 2-year rotation; minimum-tilled cotton fb. and minimum-tilled wheat in a 2-year rotation; and a perennial pasture in NW New South Wales, Australia. A backhoe pit was dug at right-angles to cracks, and a 50 mm thick layer of soil sampled from the exposed crack walls and from adjacent bulk soil in 0.3 m depth increments to a depth of 0.9 m. Soil properties evaluated were: aggregate stability (dispersion index), soil resilience to structural destruction (as geometric mean diameter of aggregates formed after puddling and drying of soil), electrical conductivity (EC1:5), exchange able cations, EC/exchangeable Na ratio, CEC, CaCO equivalent, pH, and organic C1:53. Intensive tillage resulted in soil adjacent to cracks having lower exchangeable Ca, iCEC, and CaCO3 ksequivalent, and higher organi...