Land-Use Intensification And Dairy Effluent Effects On Soil Water Repellency And Soil Carbon Of A Silt Loam Topsoil

In Canterbury, New Zealand, there has been widespread conversion of dryland sheep grazing to more intensive irrigated dairying. We determined the effects of these land uses on soil carbon on a centre-pivot sprinkler-irrigated dairy farm site, a dryland sheep site, and a non-grazed control site. The dairy site had significantly greater carbon density and carbon storage at 10-20 cm and 0-30 cm depths than the sheep farm site. The dairy farm site had significantly greater carbon stock (equivalent soil mass method) than the sheep farm site at 10-20 cm depth. The dairy farm site intensification did not adversely affect soil carbon, including carbon stock by the equivalent soil mass method. The effects of dairy effluent application on soil water repellency and water movement were investigated. The dairy site had significantly greater subcritical repellency index than the sheep site and a dairy effluent site. Further research is required across more farms and soils to confirm these results in these land uses and under other management and climate conditions.