Agronomic fortification of iron and zinc with organics in post-rainy season sorghum (Sorghum bicolor)

A field experiment was conducted during post-rainy (rabi) seasons of 2016 and 2017 under rainfed condition at Dharwad, Karnataka, to study the effect of agronomic fortification (enrichment) of iron and zinc with organics on growth, yield, economics and quality of post-rainy (rabi) sorghum [Sorghum bicolor (L.) Moench] under rainfed condition. The experiment was laid out in a randomized complete block design with 3 replications and 11 treatments. The treatments consisted of control, recommended dose of fertilizer (RDF) @ 50–25 kg N-P/ha, recommended package of practices (RPP, 50–25 kg N-P/ha + 15 kg ZnSO₄/ha), Zn + Fe @ 3.75 kg/ha each enriched with FYM, Zn + Fe @ 7.50 kg/ha each enriched with FYM, Zn + Fe @ 11.25 kg/ha each enriched with FYM, Zn + Fe @ 15 kg/ha each enriched with FYM, Zn + Fe @ 3.75 kg/ha each enriched with vermicompost, Zn + Fe @ 7.5 kg/ha each enriched with vermicompost, Zn + Fe @ 11.25 kg/ha each enriched with vermicompost and Zn + Fe @ 15.00 kg/ha each enriched with vermicompost. Soil application of Fe and Zn @ 15 kg/ha each enriched with vermicompost recorded significantly higher plant height (200.2 cm), total dry matter production (191.14 g/plant), leaf area index (5.89/plant), ear weight (94.7 g), ear length (24.8 cm), grain weight (62.0 g/ear), 1,000-grain weight (38.17 g), grain yield (4.35 t/ha), fodder yield (7.85 t/ha), gross returns (110.2 × 10³/ha) and net returns (76.2 × 10³/ha) over the control, recommended dose of fertilizer and recommended package of practices. Maximum zinc (28.44 mg/kg) and iron content (36.52 mg/kg) in grain as well as maximum uptake of zinc (116.27 g/ha), iron (161.16 g/ha), nitrogen (57.19 kg/ha), phosphorus (23.13 kg/ha) and crude protein (8.55%) were recorded with application of Fe and Zn @ 15 kg/ha each enriched with vermicompost.