Copper accumulation in New Zealand vineyard and orchard soils: A study in Central Otago, Marlborough, and Nelson : A thesis submitted in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Lincoln University

Abstract

The historic use of copper (Cu) through fungicide applications in vineyards and orchards has been widely reported to lead to accumulation in some soils. Copper (Cu) is a trace element essential for the normal functioning of all organisms, hence a deficiency in agricultural soils can negatively affect soil microbial processes and food production. However, the persistence and extensive use of Cu based fungicides can lead to Cu accumulation in the topsoil in excess concentrations. Which in turn can negatively affect soil biota and associated ecosystem processes, as well as spreading to neighbouring environments. Centuries of Cu-fungicide use in European vineyards have resulted in abundant Cu accumulation within soils consequently posing both an environmental and human health risk. However, few studies have been published about Cu accumulation in New Zealand vineyard/orchard soils or the effects of the metal on soil microorganisms in those environments. This study aimed to survey soil Cu concentrations in Central Otago, Nelson and Marlborough regions of New Zealand and provide insight towards what is driving soil Cu accumulation and the potential effects on soil fungi. Additionally, sediment samples were collected to assess Cu migration into neighbouring streams. The survey covered 63 sites where Cu concentrations ranged from 7–893 mg Cu kg-1. Soils were characterised using standard analytical methods and the speciation of Cu was analysed using single extraction techniques. The field survey revealed significant differences between fungal communities across different levels of soil Cu contamination. Additional sediment samples showed an indication of Cu migration as 70% of rivers showed an increase in Cu. This research provides further evidence towards the current Cu concentrations ranges, factors driving Cu accumulation, and effects on soil fungal communities.