Temporal availability of phosphorus and sulphur in acid inceptisol as influenced by graded application of P and S under black gram (Vigna mungo L. Hepper) production

A pot culture experiment was conducted at School of Natural Resource Management, College of Post Graduate Studies in Agricultural Sciences, CAU, Umiam, Meghalaya to assess the temporal availability of phosphorus and sulphur in acid Inceptisol of Meghalaya as influenced by graded application of P and S under black gram (cv. SBC-47) production. The treatment consisted of four levels of P (20, 40, 60 and 80 mg P kg⁻¹ soil) and four levels of S (10, 20, 30 and 40 mg S kg⁻¹ soil). The experiment was laid out in factorial completely randomized design with three replications during kharif season of 2016. The experimental soil was deficient in available phosphorus (13.85 kg ha¹) and available sulphur (15.91 kg ha¹). The results revealed that combined application of P and S had significant effects on seed and stover yield of black gram. The optimum seed and stover yield were recorded with combined application of 60 mg kg⁻¹ soil and 30 mg kg⁻¹ soil, respectively which was statistically at par with combined application of 80 mg P kg⁻¹ soil and 40 mg S kg⁻¹ soil. The assessment of temporal availability of phosphorus and sulphur at 20, 40 DAS and after harvesting of black gram in acid Inceptisol of Meghalaya indicated that available phosphorus in soil increased with each successive increasing level of P application, however it showed decreasing trend with time intervals of 40 DAS and after harvesting of black gram at each successive dose of 40, 60 and 80 mg P kg⁻¹ soil over 20 mg P kg⁻¹ soil in the presence of S fertilization. Similarly, available sulphur in soil also increased with each successive increasing level of S application, whereas it also showed decreasing trend with time intervals of 40 DAS and after harvesting of black gram at each successive dose of 20, 30 and 40 mg S kg⁻¹ soil over control as 10 mg S kg⁻¹ soil in the presence of P fertilization.