Soil properties under cotton-corn rotations in australian cotton farms

During the past decade sowing corn (Zea mays L.) in rotation with cotton (Gossypium hirsutum L.) has gained popularity among many Australian cotton growers. Research on cotton-corn rotations in Australia is sparse, although anecdotal evidence suggests that subsequent cotton yields are increased. Our objective was to quantify the impact of sowing a corn rotation crop on soil properties of Vertisols under cotton-based farming systems on 18 farms within Australian cotton-growing regions. Each site had either corn or cotton sown during the preceding summer. Soil was sampled in transects from the surface 0.3 m. Soil organic carbon concentrations and storage were higher, and exchangeable cation concentrations lower after corn than after cotton but soil structure was not significantly affected. The yield increases reported by cotton growers are, therefore, unlikely to have been caused by the soil properties measured in this study. Enhanced cycling of nutrients such as N and P through higher soil organic matter and microbial activity cannot, however, be ruled out.