Sustainable land use and trace elements

Trace Elements (TE)s are immutable. Most bind strongly to soil particles, limiting both their uptake by plants and downward mobility. These properties tend to result in the accumulation of TEs in soil. At high concentrations, all TEs are toxic. Therefore, land-use practices that result in a net addition of TEs to soil are inherently unsustainable. However, many contemporary practices, whether conventional or organic, use TEs in formulations used to control pests and diseases, or to supply nutrients to plants. For example, certified organic production systems permit the use of copper-based fungicides, despite the inevitable eventuality of increasing concentrations of copper in the topsoil.

A critical question is then to ‘… what degree of TE accumulation in soil should we tolerate? One could argue that land-use that results in trace-element concentrations in excess of threshold values after a century might be acceptable, because hopefully during this time, alternative land management practices will be developed, or low-cost remediation will become available. This nonetheless begs the question of what determines the value of the threshold. Should this be related to human health impacts? Could it be related to phytotoxicity?  Might it be related to loss of microbial biodiversity, or some other indicator of soil health?

The use of lead arsenate pesticides was halted in the 1940s and 50s as their use was deemed unsustainable. This change was enacted before lead and arsenic thresholds in most soils were exceeded.  Ironically, this change was due to the appearance of an even more effective pesticide: the more troublesome DDT! DDT, now termed a persistent organic pollutant, was banned in many countries during the 1970s. This demonstrates the importance of assessing soil functioning, quality and health in relation to the total contaminant burden. There is a critical need to fill the lacuna of our knowledge about the impact of TE build-up in soil, and to unravel the synergies and deleterious relationships between contaminants and the soil’s resident flora and fauna.  We are investigating the sustainability of some production systems in relation to their use of TEs.

Sustainable? Horticultural production often uses timber posts that are treated with copper, chromium and arsenic. These elements leach from the post into the surrounding soil.

Publications related to sustainable land use and trace elements

Greven M, Green S, Robinson B, Clothier B, Vogeler I, Agnew R, Neal S, Sivakumaran S (2007). The impact of CCA-treated posts in vineyards on soil and ground water. Water Science & Technology 56(2), 161-168.

Clothier BE, Green SR, Vogeler I, Greven MM, Agnew R, van den Dijssel CW, Neal S, Robinson BH, Davidson P (2006). CCA Transport in Soil from Treated-Timber Posts: Pattern Dynamics from the Local to Regional Scale. Hydrology & Earth System Sciences Discussions 3, 2037-2061.

Robinson BH, Greven M, Green SR, Sivakumaran S, Davidson P, Clothier BE (2006). Leaching of copper, chromium and arsenic from treated vineyard posts in Marlborough, New Zealand. Science of the Total Environment 364(1-3), 113-123.

Mills TM, Robinson BH, Sivakumaran S, Arnold B, Clothier BE, Kim N (2005). Current practice and future land-use: the sustainability of productive sector environments. Acta Horticulturae (ISHS) 694, 159-164.

Robinson BH, Mills TM, Green SR, Chancerel B, Clothier BE, Fung L, Hurst S, McIvor I (2005). Trace element accumulation by poplars and willows used for stock fodder. New Zealand Journal of Agricultural Research 48, 489-497.

Mahimairaja S, Bolan NS, Adriano NC, Robinson BH (2005). Arsenic Contamination and its Risk Management in Complex Environmental Settings. Advances in Agronomy 86, 2-64.

Thayalakumaran T, Vogeler I, Scotter DR, Percival HJ, Robinson BH, Clothier BE (2003). Leaching of copper from contaminated soil following the application of EDTA. I. Repacked soil experiments and a model. Australian Journal of Soil Research 41(2), 323-333.

Thayalakumaran T, Vogeler I, Scotter DR, Percival HJ, Robinson BH, Clothier BE (2003). Leaching of copper from contaminated soil following the application of EDTA. II. Intact core experiments and model testing. Australian Journal of Soil Research 41(2), 335-350.

Robinson BH, Bolan NS, Mahimairaja S, Clothier BE (2005). Solubility, mobility and bioaccumulation of trace elements: abiotic processes in the rhizosphere. In: Trace Elements in the Environment: Biogeochemistry, Biotechnology, and Bioremediation (Eds.  MNV Prasad, KS Sajwan, R Naidu). CRC press, Boca Raton, Florida. pp 97 – 110.

Vogeler I, Green S, Greven M, Robinson B, van den Dijssel C, Clothier B (2005). Environmental risk assessment of CCA leaching from treated vineyard posts. HortResearch Client Report to Marlborough District Council. Client Report No. 17659. Contract No. 19502.

Clothier BE, van der Velde M, Green S, van den Dijssel C, Manu V, Robinson BH, Minoneti V. (2005). CROPPRO – Sustainable agriculture in a clean environment. Final Report. HortResearch Client Report to NZAID. Report No. 2005/10057.

Marmiroli M, Robinson B, Clothier B, Bolan N (2004) Green trees for clean cheese. WISPAS No. 89.

McIvor I, Green S, Hurst S, Robinson B, Snow V, Fung L, Braaksma S, Cameron P, Hill R, Arnold J, Barnett J (2004) Coppiced Poplars and Willows Show Potential for Use in Effluent Irrigated Systems. WISPAS No. 89.

Robinson B, Greven M, Sivakumaran S, Green S, Clothier B (2004) An assessment of the leaching of chemicals from treated posts in vineyards in the Marlborough region. Commercial report to the Marlborough District Council. HortResearch Client Report 2004/12173.