Estimation of the Biochar Effect on Annual Energy Crops Grown in Post-Mining Lands

Abstract

The ability of biochar as a soil additive to influence productivity, accumulation of heavy metals and thermal characteristics of energy crops was studied. Maize, Sudan grass and Sweet sorghum were grown in containers with low humus black soil and red-brown clay. It turned out that the addition of biochar improves seed germination from 1.5% to 15% and promotes an increase in the growth of aboveground biomass and roots. For Maize and Sweet sorghum plants, the most pronounced effect is revealed on red-brown clay, and for Sudan grass on black soil. Biochar indirectly affects the intensity of accumulation of heavy metals by reducing their mobility and availability to plants. In both variants of the experiment with Maize, the application of biochar had the greatest effect on the accumulation of zinc. In the experiment with Sudan grass on black soil, the greatest effect was observed for manganese, and on red-brown clay for zinc and lead. In the experiment with sugar sorghum, the most pronounced reaction took place for copper on both substrates, and for zinc only on red-brown clay. The biochar addition led to the more complete combustion of the Sweet sorghum biomass grown on black soil and, conversely, increasing the ash content of the biomass grown on red-brown clay. During the combustion of Sudan grass biomass in the trial with red-brown clay, the addition of biochar contributed to the significant reduction in thermolysis duration and shifting of the extremum point of cellulose decomposition to the area of lower temperatures. In the case of Maize biomass, a similar effect was observed, but only in the trial with black soil