Application of Zinc Modified Biochars to Enhance Zinc Availability, Speciation and Pearl Millet Growth in Zn-Deficient Soil

Zinc deficiency poses a serious threat to numerous crops and global human population. Recently, soil biocharamendment has been promoted as a sustainable farming method. However, its consequence on the bioavailability of Znin cereal crop has not been fully addressed. In the present study, 0.01% Zn-SO4 (w/w) was loaded in fruit waste, farmyardmanure and coconut shell pyrolysis at 400℃, for 2 h to make fruit waste Zn-modified biochar (FWZn-MBC), farmyardmanure Zn-modified biochar (FYZn-MBC) and coconut shell Zn-modified biochar (CSZn-MBC). Except controltreatment, all the modified biochars were applied at 1, 2 and 4% doses on zinc availability, speciation, pearl millet growthand chemical properties in Zn-deficient soil. The obtained results show that Zn mobility in soil was 70.04% withapplication of FYZn-MBC 4% as compared to other treatments. The maximum uptake of Zn in shoot and root by pearlmillet plant was observed by 74.02 and 53% with addition of FYZn-MBC 4% as compared to control soil, due to increaseof soil organic matter. The chlorophyll SPAD values in the pearl millet aerial surface increased from 30.23 to 39.24%with application of FYZn-MBC 4% than control soil. The exchangeable fraction of Zn increased from 7.34 to 14.71%with application of FYZn-MBC 4%. The correlation matrix results indicated that CaCO3 positively correlated with soilpH, and soil organic matter had strong correlation with chlorophyll. Overall, future studies must be carried out to examinethe long-term impact of FYZn-MBC 4% on Zn phyto-availability in Zn-deficient soil