Coupling effect of phosphorus with organic manures and bioinoculant on growth and yield of black gram (Vigna mungo (L.) Hepper) in black calcareous soil

To evaluate the effect of phosphorus in conjoint with organic manures and bioinoculant for optimizing the phosphorus availability in calcareous soil, a field experiment was carried out in Kalligudi block of Madurai district using black gram (VBN 8) as a test crop. Twelve treatments were formulated with different combinations of vermicompost, farmyard manure, Bacillus megaterium (phosphorus solubilizing bacteria) and phosphorus fertilizer. Among the different combinations, application of 100% of P₂ O₅ on soil test crop response (STCR) basis incubated for 30 days with vermicompost at 1:5 ratio + PSB @ 2 kg ha⁻¹ with a recommended dose of nitrogen and potassium fertilizer recorded the maximum plant height (43.85 cm), root length (23.82 cm), nodules plant⁻¹ (27.42), dry matter production (2349 kg ha⁻¹), number of pods plant⁻¹ (28.52), seeds pod⁻¹ (6.98), 100 seed weight (4.49 g), grain yield (936 kg ha⁻¹) and haulm yield (1472 kg ha⁻¹) at harvest stage The lowest. growth and yield attributes were recorded in absolute control. Application of organic manures and bioinoculant along with inorganic fertilizer in black calcareous soil led to a greater yield of black gram of 35.9% than the application of inorganic fertilizer alone. The study concluded that the application of phosphorus fertilizer along with organic manures and phosphorus solubilizing bacteria (Bacillus megaterium) in calcareous soils improves the phosphorus use efficiency and ultimately it will enhance the growth and yield of black gram.