Monitoring soil quality in intensive dairy-farmed catchments of New Zealand: implications for farm management and environmental quality

摘要

Soil physical and chemical quality assessments were performed for the predominant soil types within four intensively grazed dairy catchments in New Zealand during the winters of 2001,2003,2005 and 2007. The four catchments monitored were in the following regions: Waikato (Toenepi stream), Taranaki (Waiokura stream), Canterbury (Waikakahi stream) and Southland (Bog Burn stream). The surveys suggest that, in general, soil quality was good. Mean soil macroporosity was initially low in the Toenepi catchment but is now within the recommended range for good pasture production. All catchments, except the Bog Burn, have showed that soil macroporosity values have increased since the study began. A considerable proportion (76%) of farms within all catchmentshas higher than optimum concentrations of soil Olsen P. These P concentrations have been maintained despite evidence from farm surveys which suggest that P fertilization rates have decreased. However, changes in soil test status following a change in fertilization policy can be slow to manifest themselves. These high levels are likely to be uneconomic and pose increased risk of P loss to waterways.