EFFECT OF ORGANIC MATERIAL AND BIOLOGICAL AMENDMENTS ON PEAR TREE PERFORMANCE AND SOIL MICROBIAL AND CHEMICAL PROPERTIES

The potential of soil for deciduous fruit production may be increased by biological amendment application, especially in pear trees that generally suffer from poor, initial root development. The objective of the study was to integrate various biological management practices into a conventional pear orchard and investigate the effect on tree performance and soil chemical and microbial properties over a six year trial period, including two harvest years. Maintaining a wheat straw mulch in the tree row showed few effects on tree performance, despite significant changes in soil microbial functioning and activity. Annual compost applications significantly improved Bacillus numbers, activity of various soil enzymes important in soil fertility, as well as increased extractable soil P, K, Ca and Mg and total soil N and C. Effects with amendments on urease, acid phosphatase and β-glucosidase activity were more significant in a non-mulched system. Yield over two years was improved by 21% when compost was applied compared to 51% when both compost and compost extract were applied, when compared to control plots. Regular compost extract application throughout the growing season may result in maximum efficiency of nutrient utilisation. More research is needed on compost extract quality and the mechanisms of action involved.