Effect of Zinc Application Strategies on Growth, Productivity, Zinc Uptake by Rice and Residual Soil Zinc Status under Rice-Wheat Cropping System of Central India

The rice-wheat cropping system in India, particularly in Madhya Pradesh, faces widespread zinc deficiency, which limits yield and grain quality. Foliar zinc application, nano-fertilizers, and zinc solubilizing bacteria (ZSB) have proven effective in enhancing crop growth, zinc uptake, and soil nutrient status, offering sustainable strategies for improving productivity and nutrient use efficiency. In order to investigate the effects of various zinc management strategies on rice within a rice-wheat cropping sequence, a field experiment was carried out in the Zn-deficient Vertisols of Central India during the kharif seasons of 2022-23 and 2023-24 at the Research Field of the Department of Soil Science and Agricultural Chemistry, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, Madhya Pradesh. The study used a Randomized Block Design to assess twelve treatments, including soil-applied zinc, foliar sprays (ZnSO4 and Nano-Zn) and microbial bio-inoculants (ZSB) at different recommended doses of NPK fertilizers (RDF). The results demonstrated that crop performance was greatly enhanced by integrated nutrient management. In particular, growth, grain production (64.2 and 61.7 q ha-1) and total Zn uptake (298.0 and 320.2 g ha-1) by rice were optimized during the two seasons by the synergy of RDF + 5 kg Zn ha-1 + ZSB (T6). Interestingly, treatment T6 raised grain production by roughly 5-8% over RDF alone and by over 80% over the unfertilized control. Compared to foliar-only treatments, soil-applied zinc retained far higher residual DTPA-extractable zinc (0.66–0.71 mg kg-1) in terms of soil health, guaranteeing a better carry-over benefit for the subsequent wheat crop. While, Nano-Zn formulations showed similar efficacy to traditional zinc sulphate sprays. This study emphasizes the need to combine mineral and biological inputs to enable sustained Zn biofortification and long-term soil fertility in the rice-wheat systems of the region, even though Nano-Zn formulations shown comparable efficiency to conventional zinc sulphate sprays.