Comparison of soil quality targets and background concentrations in soil of the Waikato Region, New Zealand

摘要

Current targets used for assessing soil quality in New Zealand were compared with 95% confidence intervals of measurements of background soils from the Waikato region, New Zealand. Indicators analysed included pH, total C and N, Olsen P, anaerobicaUymineralised N, bulk density, macroporosity, aggregate stability, As, Cd, Cr, Cu, Hg, Pb, Ni and Zn. While background concentrations are easily applied to some measurements (metals), for other soil quality measurements (particularly those with optimum ranges rather than just maximum allowable limits such as bulk density and macroporosity) the concept is more difficult to apply. Background sites met the targets for pH, total C, aggregate stability, Zn, Cu, Pb, As, Cr Ni, Cd and Hg. Some background sites didn't meet the targets for Olsen P, as New Zealand soils are naturally low in phosphorous. Also, some sites didn't meet the targets for bulk density and macroporosity indicating an erosion risk. Targets for total N and anaerobicaUy mineralised N on theirown are inadequate to assess N status and the N leaching risk, and trends in these measurements may be more valuable than meeting an actual target.