Application of zinc modified biochars to enhance zinc availability, speciation and bajra growth in Zn-deficient soil

Abstract

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