Combined biochar and manure addition to an agricultural soil benefits fertility, microbial activity, and mitigates manure-induced CO2 emissions

The importance of blending biochar into manure prior to its application as a soil amendment was investigated by this laboratory and field study, hypothesizing an (i) increase in soil fertility; (ii) improvement in microbial activity; and (iii) reduction in manure-induced CO₂ emissions after combining amendments. Biochar was mixed with manure (50:50 V/V) and aged in field conditions for 6 months whereafter pristine biochar, manure, and manured biochar (50:50 V/V) were incorporated into an agricultural drought-prone Regosol. All treatments and soil mixtures were incubated, with laboratory measurements of CO₂ emissions taken using a coupled column respirometer set up, whilst nutrient availabilities as well as enzymatic activities were also tested.