Soil fertility management in apple orchard with microbial biofertilizers

Intensification of horticulture in Russia involves planting of new high-density orchards with drip irrigation and fertigation as well as intensification of the exploitation of traditional orchards. This approach involves an increase in mineral fertilizer application imposing the risk of soil fertility loss. For several reasons, the use of traditional organic fertilizers like manure in orchards is currently marginal. Although bacteria-based biofertilizers cannot substitute mineral fertilizers completely, they can significantly reduce the need for mineral fertilizer application. The effect of microbial biofertilizers of the brands “Azotovit” (Azotobacter chroococcum), “Phosphatovit” (Bacillus mucilaginosus), as well as a mixture of bacteria and the fungus, “Organic” (Azotobacter chroococcum, Bacillus subtilis, Bacillus megaterium, Trichoderma harzian) was studied in two field experiments. In the experiment #1, the preparations “Azotovit” and “Phosphatovit” were delivered through a drip irrigation system in various combinations with mineral fertilizers. In experiment #2, the preparation “Organic” was also applied to the soil with irrigation water, also in combination with the mineral fertilizer. When solely applied, none of the studied preparations changed significantly the soil nutrient content and yield as compared with the variant fertilized by the mineral fertilizer at the maximum studied application rate. The combination of the microbial biofertilizer and mineral fertilizers applied at a low rate ensured the yield commensurate to that obtained under high-rate application of the mineral fertilizer