Influence of crop rotation 51 and intercropping on microbial populations in cultivated fields under different organic amendments

Abstract

The present investigation was carried out with an aim to study the microbial populations (fungi and bacteria) of organically amended soils under three different crop cycles, i.e. maize (Zea mays L.), French bean (Phaseolus vulgaris L.) and soybean (Glycine max). From the selected crops, maize and French bean were grown in rotation with soybean as an intercropping crop. The different organic amendments incorporated into the experimental field include farmyard manure (FYM), plant compost (PC), vermicompost (VC) and integrated compost (INT) (combination of FYM, PC and VC in 1:1:1 ratio). A control (CTRL) plot without any fertilizer was also maintained. Treatment-wise, the fungal population was increased by FYM amendment; however, PC amendment resulted in higher bacterial population. Significant ariations were observed in the microbial populations (fungi and bacteria) between the organic treatments according to Tukey’s test (ANOVA) at p ≤ 0.05. The dominant fungal species isolated include Acremonium spp., Aspergillus spp., Cladosporium cladosporioides, Fusarium oxysporum, Gongronella butleri, Humicola spp., Mortierella gamsii, Phoma eupyrena, Paecilomyces carneus, Penicillium spp., Pythium irregulare, Rhizopus stolonifer and Trichoderma spp., Arthrobacter sp., Bacillus spp. and Pseudomonas aeruginosa were the dominant bacterial species isolated. It can be suggested that diverse plant residues returned to the soil by rotation of crops and improved the organic matter resulting in higher microbial populations. The study also revealed that the types of crop grown and the degree of fertilizer decomposition have a significant impact on the microbial populations.