Nutrient deficiencies in soil–crop contexts and inappropriate managements are the important reasons for low crop productivity, reduced nutritional quality of agricultural produce and animal/human malnutrition, across the world. The present investigation was carried out to evaluate nutrient deficiencies of sulphur (S) and micronutrients [zinc (Zn), boron (B), iron (Fe), copper (Cu) and manganese (Mn)] in agricultural soils of India for devising effective management strategies to achieve sustainable crop production, improved nutritional quality in crops and better animal/human health. A total of 2,42,827 surface (0–15 cm depth) soil samples were collected from agriculture fields of 615 districts lying in 28 states of India and were analysed for available S and micronutrients concentration. The study was carried out under the aegis of All India Coordinated Research Project on Micro- and Secondary-Nutrients and Pollutant Elements in Soils and Plants. The mean concentrations were 27.0 ± 29.9 mg kg⁻¹for available S, 1.40 ± 1.60 mg kg⁻¹for available Zn and 1.40 ± 4.70 mg kg⁻¹for available B, 31.0 ± 52.2 mg kg⁻¹for available Fe, 2.30 ± 3.50 mg kg⁻¹for available Cu and 17.5 ± 21.4 mg kg⁻¹for available Mn. There were variable and widespread deficiencies of S and micronutrients in different states. The deficiencies (acute deficient + deficient + latent deficiency) of S (58.6% of soils), Zn (51.2% of soils) and B (44.7% of soils) were higher compared to the deficiencies of Fe (19.2% of soils), Cu (11.4% of soils) and Mn (17.4% of soils). Out of 615 districts, > 50% of soils in 101, 131 and 86 districts were deficient in available S, available Zn and available B, respectively. Whereas, > 25% of soils in 83, 5 and 41 districts had deficiencies of available Fe, available Cu and available Mn, respectively. There were occurrences of 2-nutrients deficiencies such S + Zn (9.30% of soils), Zn + B (8.70% of soils), S + B (7.00% of soils) and Zn + Fe (5.80% of soils) to a greater extent compared to the deficiencies of Zn + Mn (3.40% of soils), S + Fe (3.30% of soils), Zn + Cu (2.80% of soils) and Fe + B (2.70% of soils). Relatively lower % of soils were deficient in 3-nutrients (namely S + Zn + B, S + Zn + B and Zn + Fe + B), 4-nutrients (namely Zn + Fe + Cu + Mn) and 5-nutrients (namely Zn + Fe + Cu + Mn + B) simultaneously. The information regarding the distribution of deficiencies of S and micronutrients (both single and multi-nutrients) could be used by various stakeholders for production, supply and application of right kind of fertilizers in different districts, states and agro-ecological regions of India for better crop production, crop nutritional quality, nutrient use efficiency, soil health and for tackling human and animal malnutrition.

Nanoparticles (NPs), due to their tailored properties, serve as potential sources of nutrients for the biofortification of edible grains. Chickpeas are a valued legume crop, widely consumed in developing countries. Thus, to improve the Zn and Fe content in chickpeas, a two-year study was conducted to examine the potential of the foliar application of mineral (0.5% Zn and Fe), chelated (0.3% Zn and Fe) and nanoforms (0.5% ZFN) of fertilizers to enhance Zn and Fe content in chickpea. The foliar application of 0.5% ZnO NPs + 0.5% Fe₂O₃ NPs (ZFN) at the pre-flowering stage showed the highest potential to increase grain yield, Zn and Fe content and their uptake as a single foliar application of nano-fertilizers showed comparable results to two foliar applications of mineral and chelated forms. The grain and straw yield (14.07 and 33.04 q ha⁻¹, respectively) under ZFN treatment was significantly higher over the control (9.20 and 27.49 q ha⁻¹, respectively). A similar trend was observed for Zn and Fe content in grain (42.29 and 86.51 mg kg⁻¹, respectively). For nutrient uptake, ZFN treatment showed the highest uptake of Zn and Fe in grain (604.49 and 1226.22 g ha⁻¹, respectively) and straw (729.55 and 9184.67 g ha⁻¹, respectively). Thus, nano-fertilizers, due to their altered structural properties, demonstrated higher translocation over the mineral and chelated forms of nutrient fertilizers and thus improved yield and nutrient content to a greater extent. Thus, the foliar application of 0.5% ZnO NPs + 0.5% Fe₂O₃ NPs may prove to be a feasible option for the enrichment of chickpeas with Zn and Fe to ameliorate malnutrition in burgeoning human populations.