Effect of soil surface management practices on soil and root microbiology, rootzone parameters and tree performance in apple

The objective of this study was to investigate the effects of different soil surface management practices on the physical, chemical and, particularly, the biological properties of the soil.  The general context was that of apple production.  Two treatments: chemical weed control (T1, T2) and mulching (T4, T6, T7), were applied in the tree row in combination with different treatments in the work row.

Soil microbial communities seem to be sensitive to changes in the environment caused by surface management practices.  The most marked effects were caused by the practices applied to the tree row.  Chemical control clearly had negative impacts on the arbuscular mycorrhizal status, microbial enzyme activity, and microbial diversity, whereas mulching had a positive impact.  DNA profiling of microbial community diversity suggested the same.  Discriminant Analyses (DA) also confirm these treatment effects.  They further showed that the main effects could be sustained over several consecutive years.  Such responses, by the root and by soil microbes, are linked to alterations in soil chemical properties (correlation data), triggered by the two main treatment effects.  Mulching, together with a compost tea spray in the tree, and that of a cover crop in the work row, has particularly been proven to have rendered stimulating effects on soil microbiology.  These results support the possibility of a safer, more environmentally sound practice, more in line with sustainable farming practices, as compared with conventional methods. It does not however, totally exclude the use of an integrated approach.

Please note: It was agreed that the final conclusions and recommendations of this report will be included in the final report of project 282010, which will be submitted later this year.