ISHS Acta Horticulturae 694: International Symposium on Harnessing the Potential of Horticulture in the Asian-Pacific Region
CURRENT PRACTICE AND FUTURE LAND-USE: THE SUSTAINABILITY OF PRODUCTIVE SECTOR ENVIRONMENTS |
| Authors: | T.M. Mills, B.H. Robinson, S. Sivakumaran, B. Arnold, B.E. Clothier, N. Kim |
| Keywords: | Heavy metals, cadmium, copper, zinc, arsenic, persistent organic pollutants (POPs), dieldrin |
| Abstract:
There are many cumulative contaminants used in primary productive sectors. Metals such as zinc (Zn) and copper (Cu) are present in pesticides applied to horticultural crops. Cadmium (Cd) may be applied as a co-contaminant in phosphate fertilisers. Arsenic (As), present in treated timber posts and historically used as a sheep and orchard biocide represents both a legacy contaminant and a current risk. Many of these metal pesticides are still in use and therefore continue to accumulate. Both Zn and Cd pose the most threat to pastoral farming systems with estimated years to reach maximum soil guideline levels of 75 and 27 years respectively for dairy production systems. Under horticultural production systems, Cu poses immediate threat. We estimate 7.7 years before soil guideline levels are exceeded under current management practices for avocado. Persistent organic pollutants (POPs) including dieldrin are no longer used in production systems within New Zealand but their persistence in soil means they still pose limitations to land-use. These organic pollutants may, in theory, degrade with time. However, our research indicates complex interactions with the soil matrix that limits their in situ degradation. | |
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