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Correction and standardization of critical limit of zinc for maize (Zea mays L.) crop: Bangladesh perspective

Abstract Critical limit (CL) determination of zinc (Zn) is very important for predicting response of maize crop to its application in soils and for the crop’s actual fertilizer requirement. This study was conducted at Bangladesh Agricultural Research Institute, Gazipur, to determine the CL of Zn for maize grown in 20 soils collected from the five Agro–Ecological Zones during January to March, and April to June of 2017. The available Zn content of soils and maize biomass were estimated utilizing the extraction method with 0.005 M diethylene triamine pentaacetic acid (DTPA). During January to March and April to June 2017, the amount of DTPA extractable Zn in different soils ranged from 0.60–3.25 mg kg−1 and 0.50–1.68 mg kg−1, respectively. During both periods of crop growth (January to March and April to June, 2017), the soil available zinc was negatively significantly correlated with soil pH, available P, exchangeable Ca, exchangeable Mg and positively significantly correlated with relative dry matter (DM) yield. Soil Zn also positively significantly correlated with maize tissue Zn content (r = 0.521*). However, the CL of Zn were estimated to be 0.84 mg kg−1 in soils and 26.1 mg kg−1 in maize tissue for maize cropping as determined by Cate and Nelson’s (1965) graphical procedure. Maize crop may respond to Zn application in soils containing Zn at/below the above level. This data may be used for predicting plant response to Zn fertilizer and development of crop Zn nutrition guide for maximum production.