The effects of organic vs. conventional fertilisation practices on microbial functional diversity, total microbial counts, biological activity and soil suppressiveness against a representative soil-borne disease were studied. The study site was an experimental organic plum orchard, located in Jezre'el Valley, Israel. A control treatment (trt.) was fertilised conventionally, according to commercial practices, while all plant protection practices were handled according to organic practices. The organic trt. was fertilised with compost and feather meal. The total applied N was similar in both treatments, at ~350 Kg ha-1 year-1. Treatments were compared for their general microbial activity (counts, fluorescein diacetate hydrolysis, heat generation as measured using calorimetry) and for functional diversity using Biolog Eco plates®. Biolog plates were inoculated with increasing soil dilutions (103 , 104 ,105 ) and colour development was recorded. Treatments were compared by richness and Shannon index. Suppressiveness of the soils was assessed using the pathosystem melon (Cucumis melo cv. Ofir) and F. oxysporum f. sp. melonis. Microbial activity was higher in the organic trt. as compared to the control in all tested parameters. Functional diversity of the 105 but not of lower dilutions was significantly higher in the organic treatment (trt.) both in terms of richness and Shannon index. The organic trt. suppressed wilting of fusarium-inoculated melon plants. It is concluded that substituting chemical fertilisers with compost facilitated the development of healthier soil.
The effects of organic vs. conventional fertilisation practices on microbial functional diversity, total microbial counts, biological activity and soil suppressiveness against a representative soil-borne disease were studied. The study site was an experimental organic plum orchard, located in Jezre'el Valley, Israel. A control treatment (trt.) was fertilised conventionally, according to commercial practices, while all plant protection practices were handled according to organic practices. The organic trt. was fertilised with compost and feather meal. The total applied N was similar in both treatments, at ~350 Kg ha-1 year-1. Treatments were compared for their general microbial activity (counts, fluorescein diacetate hydrolysis, heat generation as measured using calorimetry) and for functional diversity using Biolog Eco plates®. Biolog plates were inoculated with increasing soil dilutions (103 , 104 ,105 ) and colour development was recorded. Treatments were compared by richness and Shannon index. Suppressiveness of the soils was assessed using the pathosystem melon (Cucumis melo cv. Ofir) and F. oxysporum f. sp. melonis. Microbial activity was higher in the organic trt. as compared to the control in all tested parameters. Functional diversity of the 105 but not of lower dilutions was significantly higher in the organic treatment (trt.) both in terms of richness and Shannon index. The organic trt. suppressed wilting of fusarium-inoculated melon plants. It is concluded that substituting chemical fertilisers with compost facilitated the development of healthier soil.