Abstract
Higher grain Zn concentration is desirable to combat human Zn deficiency. A total of 58 farmers’ fields were surveyed from
districts of Multan and Lodhran to represent cotton-wheat rotation zone of Punjab. Soils were sampled separately from the
surface (0–15 cm depth) and subsurface (15–30 cm depth) layers. Within 5 m2 of soil sample, about 100 spikes from mature
tillers of wheat were also collected. Nearly all subsurface and 76% of the collected surface soil samples were deficient in
plant available Zn resulting in grain Zn concentration of 20 µg g
−1
, on average. The inherent capacity of subsurface soil layer
to supply Zn positively correlated with grain Zn concentration (r=0.33, n=58; P=0.01). Organic matter content (r=0.32, n=58;
P=0.02) in subsurface layer and soil salinity (ECe) of both layers (r=−0.53, n=58; P<0.01 for ECe of both layers) were the
other major soil characteristics that significantly correlated with grain Zn concentration. Zinc bioavailability in wheat grains,
estimated by [phytate]:[Zn] ratios and trivariate model of Zn absorption, was low. Present study indicated a need to reduce
current grain [phytate]:[Zn] ratio (46, on average) and to increase the current trivariate model based estimated Zn
bioavailability (1.5 mg Zn for 300 g flour, on average) by about 2-folds. Conclusively, Zn fertilization strategy for southern
Punjab was suggested as a solution to human Zn deficiency and low grain yields.
