Soil microbial and enzymatic responses to various sources of potassium in fodder maize and sugargraze

Abstract

The field experiment was conducted during Kharif season of 2018 at NDRI, Karnal to study the influence of various sources of potassium on soil microbial population, enzymatic activities and yield of fodder crops. The experiment was laid out in the split-plot design with 16 treatment combinations and replicated thrice. In the main plot treatment, two fodder crops, viz., maize (Zea mays) and sugargraze (Sorghum bicolor L. × Sweet sorghum × Sorghum sudanese L.), were included while potassium treatments were executed under subplot treatment. The results revealed that, application of K50 + KSB + 2% KNO3 had a significant influence on biomass production and 30.3 and 22.4% green and dry fodder yield, enhancement was recorded over control. Soil microbial biomass carbon (MBC) was not significantly affected by fodder maize and sugargraze crops at 30 DAS and harvest. However, potassium application had significant influence on soil MBC and a higher values (167 and 185 µg/g dry soil) were recorded with K25 + KSB + 2% KNO3 treatment at 30 DAS and harvest over control, respectively. The soil enzymatic activities dehydrogenase (17.4 and 21.9 µg TPF/g soil/day) and phosphatase (55.4 and 72.8 µg PNP/g soil/hr.) and microbial population counts viz., bacteria (17.12 × 106 and 27.45 × 106 CFU/g soil), actinomycetes (28.2 × 105 and 36.2 × 105 CFU/g soil) and fungi (12.8 × 105 and 18.3 × 105 CFU/g soil) were also remarkably influenced with potassium treatments and found significantly higher at 30 DAS and harvest respectively over control under application of K25 + KSB + 2%.