Influence of phosphorus, sulphur and boron on growth, yield, nutrient uptake and economics of Indian mustard (Brassica juncea) under rainfed conditions

A field experiment was conducted during the winter seasons of 2001–2003 at New Delhi, on deep sandyloam soil analyzing medium in available P and S, to study the effect of 3 levels of phosphorus (0, 25 and 50 kg P₂O₅/ha), 3 levels of sulphur (0, 20 and 40 kg S/ha) and 2 levels of boron (control and 0.2% spray of borax at 50% flowering) on rainfed Indian mustard [Brassica juncea (L.) Czernj. & Cosson]. Progressive increase in P and S levels increased yield attributes and seed yield, but the increase in seed yield was significant only up to 25 kg P₂O₅/ha and 20 kg S/ha. Indian mustard removed more S than P. Owing to P and S levels, P, S and B uptake was significant only up to 25 kg P₂O₅ and 20 kg S/ha. Seed-yield response to tested levels of P and S was found quadratic. Based on the response equation, optimum dose of P₂O₅, response/kg P and returns/re-investment on P₂O₅ were 45.4 kg P₂O₅/ha, 10.8 kg and Rs 4.82 respectively. Corresponding figures for S application were 30.9 kg S/ha, 13.3 kg seed/kg S and Rs 5.63/Re investment on S. Net returns were the maximum with 50 kg P₂O₅/ha (Rs 19,214/ha) and 40 kg S/ha (Rs 17,664/ha), whereas benefit: cost ratio was the highest with 25 kg P₂O₅ (3.30) and 20 kg S/ha (3.35). Boron application also recorded marked improvement in seed yield (10.6%), uptake of P (8.3%), S (7.30%) and B (14.3%), and net returns (13.9%) and benefit: cost ratio (4.8%).