Application of biochar and sulfur-modified biochar in a saline-sodic and calcareous soil: Effects on soil water content, soil biochemical properties and millet (Panicum miliaceum) yield

Aims Soil microbial and enzymatic activity have important roles in soil health, nutrient cycle, and plant growth. Biochar is excellent biomass for increasing soil water content, but some of the biochar compounds due to high pH are harmful to the soil. This study aimed to investigate the effect of biochar and sulfur-modified biochar on improving, soil water content and biochemical properties of soil in a millet cropping system. Methods The field experiment was performed in a completely random design with three replications under field conditions. Experimental treatments included control, 15 t ha − 1 sunflower biochar (B), and 15 t ha − 1 sulfur-modified biochar (BS). Results Soil water content in B treatment was higher than that in BS treatment. B and BS treatments improved soil biological properties (MBC, BR, CAT, DHA, UA and ALP) compared to control. Application of B and BS treatments decreased soil EC and SAR compared to the control. The highest (8.26) and lowest (7.83) values of soil pH were related to B and BS treatments, respectively. Treatment of soil with B and BS enhanced soil DOC (90% and 33%), AN (74% and 48%), and AP (60% and 96%) compared to control. Application of B and BS treatments enhanced plant nutrients such as N, P and K and increased RWC (40% and 14%) and plant yield (58% and 115%) compared to the control. Conclusions The sulfur increased the efficiency of biochar on amending saline and calcareous soil and enhance plant yield through improving chemical properties (pH and CEC) of biochar.