Objectives Effects of a alkaline fertilizer on soil microbial activity and microbial diversity were studied, and mechanism of the alkaline fertilizer on reducing the incidence of FOC in banana plantation was revealed.

Methods A pot experiment with the split plot design was conducted.The main plot was compound fertilizers whose pH values were 5.5, 7.0 and 8.0, and the subplot was inoculation with Fusarium oxysporum f. sp. cubensce (E.F.Smith) Snyder et Hasen (FOC) at ×10⁶ cfu/g and without inoculation. The diversity of soil microbial communities and occurrence of banana wilt disease were investigated.

Results 1) The incidence of FOC in banana treated with the alkaline and neutral fertilizer treatments significantly decreased the wilt infection and disease index, which were decreased by 38 and 16 percentage points in the alkaline fertilizer treatment compared to those treated with the acid fertilizer. 2) The banana biomass in the alkaline fertilizer treatment was significantly higher than those in the neutral and acid fertilizer treatments under the condition of FOC inoculation, the increments were by 15% and 23%, respectively. 3) The amount of FOC and fungi population in the soils treated with the alkaline fertilizer were remarkably lower, the decrements in FOC and fungi population were by 60% and 51% respectively, while the amount of actinomycetes and bacteria population were significantly higher than those in the acid fertilizer treatment, being 1.22 and 2.25 times of those in the acid fertilizer treatment, respectively. 4) Compared to the acid fertilizer treatment, the average well color development (AWCD) in the alkaline fertilizer treatment was significantly higher, and the Richness and Shannon-Weaver diversity index were also notably higher.

Conclusions The application of alkaline fertilizer could obviously increase population of actinomycetes and bacteria, the soil microbial community structure become healthy as the soil microbial activity and diversity are increased, and the growth and infection of FOC and fungi are significantly prevented during banana growth.