Monday, November 13, 2006

Land Use and Management History Effects on Soil Quality and Crop Performance in New Zealand.

Michael Beare, Craig Tregurtha, and Erin Lawrence. Institute of Crop & Food Research, Private Bag 4704, Christchurch, 8020, New Zealand

Understanding the effects of soil and crop management practices on soil quality is important to developing management recommendations that conserve the soil resource and sustain crop performance. This paper describes relationships between crop and soil management practices, soil quality and crop performance on cropping farms in the Canterbury and Southland regions of New Zealand (1999-2003). Overall, tillage appears to be the most important factor affecting the soil structural condition of cropping soils in Canterbury. Crop type is also important but can be confounded by crop-specific tillage practices. Soil organic matter content is important to maintaining soil water holding capacity (i.e. water content at field capacity) on cropping paddocks in Canterbury. Crop yields in Canterbury were well related to soil structural condition scores and aggregate stability. Tillage also appears to be important on mixed cropping farms in Southland and is related to the length of the cropping phase in mixed-cropping rotations. Winter grazing of dairy cows on Southland cropping farms often results in significant soil structural damage. Under continuous cropping, recovery of these properties appears to be slow (1-3 years) and can lower crop yields by 15-30% compared to non-winter grazed paddocks.