Synergistic Effect of Organic, Inorganic and Biofertilizers on Soil Microbial Activities in Rhizospheric Soil of Green Pea

To study the effect of incorporation of organic, inorganic and biofertilizers on rhizospheric microbial population and enzyme activities at various time intervals in pea crop, the experiment was laid in randomized blocked design in triplicate with plot size of 7 ×2.5 m2 using Punjab-88 variety. Study was conducted during winter season of 2015-16 in field of Department of Agronomy, Punjab Agricultural University, Ludhiana, India. Enumeration of bacteria, fungi, actinomycetes, diazotrophs, PGPR and PSB was done on Nutrient Agar medium, Glucose Yeast Extract medium, Kenknight’s medium, Jensen’s medium, King’s B medium and NBRIP medium respectively, using serial dilution spread plate technique. Activities of soil enzymes (Alkaline phosphatase, Urease and Dehydrogenase) were studied. Significantly higher total bacterial population (150 ×107 CFU g-1 of soil) and PGPR (218 ×105 CFU g-1 of soil) population was observed in treatments when there was combination of organic, inorganic and consortium biofertilizer. Actinomycetes remained unaffected with different fertilizers. Biofertilizer used in combination with FYM resulted in significantly higher population of fungi (20 ×103 CFU g-1 of soil), diazotrophs (140 ×105 CFU g-1 of soil) and PSB (80 ×104 CFU g-1 of soil). Among rhizospheric soil enzyme activities, alkaline phosphatase activity was significantly higher in treatment with FYM +consortium biofertilizer while dehydrogenase activity was higher in treatment with inorganic fertilizer +FYM +consortium biofertilizer. Urease activity showed a variable pattern during different time intervals. Microbial activities were also affected by different stages of plant growth. Total bacterial population showed positive correlation with enzyme activities during initial stages of plant growth but showed negative correlation with urease activity during late stages of plant growth. Combined application of organic and inorganic fertilizers resulted in improved soil microflora leading to significantly higher enzyme activities which were further enhanced by inoculation of biofertilizers.