Zinc dynamics and yield sustainability in relation to Zn application under maize-wheat cropping on Typic Hapludalfs

Globally, widespread micronutrient deficiencies have become a serious challenge for sustaining crop production systems and food security. Of all micronutrients, zinc (Zn) is the most deficient one. Hence, efficient Zn management is essential to achieve potential crop yields. A six-year field experiment was conducted on Typic Hapludalfs with maize-wheat cropping system to study the direct and residual Zn management effect on maize and succeeding wheat crop, respectively. The effect on soil available Zn was also evaluated. Three Zn application frequencies, viz. once (single year), alternate (every alternate year), and continuous (every year) at four Zn application rates, viz. 2.5, 5.0, 7.5, and 10.0 kg ha−1 along with one control (no Zn) were investigated from 2013 to 2019. The Zn application significantly improved the crop yields, system sustainability, DTPA-Zn, and different Zn pools without causing any environmental risk. In general, the continuous application of Zn at 5.0 kg ha−1 produced the best yield and system productivity. The economically optimal system productivity was obtained with 5.93 and 7.46 kg Zn ha−1 for alternate and continuous frequency Zn application, respectively. The optimal DTPA-Zn to attain the highest system productivity of 7.64 t ha−1 was 1.55 mg kg−1. The crop yields were mainly influenced by the alternate and continuous application of Zn at lower rates (2.5, 5.0, and 7.5 kg ha−1), whereas Zn fractions and DTPA-Zn were significantly influenced by Zn application at higher rate (10 kg ha−1) irrespective of Zn application frequencies. Similar results were obtained with PCA analysis. The results of this study suggested the rationality of Zn application in attaining economically viable and environmentally sound maize-wheat system productivity.