Continuous Cotton and Cotton-Wheat Rotation Effects on Soil Properties and Profitability in an Irrigated Vertisol

ABSTRACT The combination of cotton (Gossypium hirsutum L.)-wheat (Triticum aestivum L.) rotations and minimum tillage is known to be superior to cotton monoculture in maintaining soil quality in eastern Australian Vertisols. Furthermore, sowing cotton into retained wheat stubble can minimize erosion and runoff, reduce off-field movement of pesticide residues and nutrients, and protect cotton seedlings from attack by heliothis moths. However, the consequences of sowing irrigated cotton into standing wheat stubble on soil quality and profitability are unknown. The objective of this study was to quantify the changes in several soil quality indices, viz. soil organic C (SOC), salinity, sodicity, structure, exchangeable cations, and profitability due to sowing irrigated cotton into standing wheat stubble. The sodicity indices measured were ESP (exchangeable sodium percentage) and EC1:5/exchangeable Na, and structural indices were in situ macroporosity at field capacity and bulk density. Soil properties and pro...