Soil nutrient dynamics and microbial activity as influenced by fertility levels and liquid biofertilizers in gobhi sarson (Brassica napus L.)

The experiment was conducted during winter (rabi) season of 2022-23 at CSKHPKV Shivalik Agricultural Research and Extension Centre (SAREC), Kangra, Himachal Pradesh to study the effect of fertility levels and liquid biofertilizers on soil nutrient status and microbial activity in gobhi sarson (Brassica napus L.). The experiment was laid out in a split plot design with three fertility levels (control, 75% of recommended dose of fertilizers and 100% RDF) in main plots and six liquid biofertilizers [Azotobacter, phosphate solubilizing microorganism (PSMO), potassium mobilizing biofertilizer (KMB), NPK consortia + zinc solubilizing biofertilizer (ZSB), ZSB and control (no biofertilizer)] in sub plots. The results demonstrated that application of 100% RDF recorded higher available N (277 kg/ha), P (20.8 kg/ha) and soil microbial population of bacteria, fungi and actinomycetes. However, 75% RDF recorded higher available K (225.1 kg/ha) and higher DTPA extractable Zn (2.76 mg/ha) were recorded in control treatment. Among liquid biofertilizers, higher available nitrogen, phosphorus, potassium and DTPA extractable zinc in soil was recorded with Azotobacter, PSMO, KMB and ZSB treatments, respectively. Similarly, higher microbial population was recorded with Azotobacter. However, the effect of fertility levels and liquid biofertilizers on soil organic carbon was not significant.