Analysis of soil biological activity and microbial functional diversity under organic and conventional farm management regimes : A report submitted in partial fulfilment of the requirements of the Degree of Master of Applied Science at Lincoln University

Abstract

There is increasing concern about environmental and health damage caused by many agricultural and food industry practices and a growing appreciation of the environmental and health benefits of certified organic production systems. Lincoln University has explored sustainable organic techniques for many years, contributing to the advancement of organic food production in New Zealand. As part of continuing research, comparison of biological activity between organic and conventional farming regimes was examined using the Bait Lamina Test. The method determined the feeding activity of soil organisms within and between management regimes and the performance of soil invertebrates in conjunction with soil microorganisms on the nutrient cycle in farmland. Data from organic and conventional arable and apple field analysis produced significant variations, with organic arable fields significantly higher in biological activity than conventional arable fields. Apple field analysis produced no significant difference between management regimes. The Bio log EcoPlate community level approach examined soil community structural differences with respect to type of management through analyses of carbon substrate utilization measures of diversity. Our analysis demonstrated that the Biolog EcoPlate can detect considerable variation in the ability of microbial communities to metabolise different carbon compounds. By applying substrate patterns of diversity, similarity of community structures was observed in the apple field comparisons under both management regimes. Arable field analysis produced discemable differences of individual and guild specific carbon utilization patterns. The Bait Lamina test and Biolog EcoPlate offer potentially time and energy saving methods of determining soil biological activity and microbial functional diversity respectively, in soil ecosystems. However, the usefulness of these methods is in comparative studies where the effects of any factors or treatments influencing processes within the different management regimes can be defined over time.