Soil Microbial Population as Influenced by Weed Management Practices under Different Rice Crop Establishment Methods

Rice crop establishment and herbicide application methods may influence culturable soil microbial populations. This study evaluated bacterial, fungal and actinomycete populations under four rice establishment methods and six weed management treatments at the Agricultural Research Station, Kampasagar, during the kharif seasons of 2024 and 2025. The field experiment followed a strip-plot design with three replications. Establishment methods comprised dry converted wet seeding using a seed drill, wet direct seeding using a drum seeder, drone seeding in puddled soil and manual transplanting. Weed management included two herbicide programmes applied by drone or manual knapsack sprayer, a weed-free treatment and a weedy check. Soil samples were collected initially, at 60 days after sowing or transplanting, and at harvest. Bacteria, fungi and actinomycetes were enumerated using serial dilution, and the data were analysed after logarithmic transformation. Establishment methods significantly influenced the measured microbial populations, with manual transplanting generally recording the highest values and dry converted wet seeding recording the lowest. Weed management treatments also differed in microbial populations at 60 days after sowing or transplanting and at harvest. The weedy check and weed-free treatments generally maintained higher populations than herbicide-treated treatments. Drone and manual knapsack applications produced comparable microbial populations. No significant interaction between establishment and weed management methods was observed. Under the experimental conditions, crop establishment and weed management practices were associated with differences in culturable soil microbial populations, whereas herbicide application modes showed broadly comparable results.