Dr Muhammad Riaz1, Dr. Muhammad Saleem Arif1, Dr. Qaiser Hussain2, Mrs. Samar Fatima1, Dr. Tahira Yasmeen1, Dr. Muhammad Arif3
1Department of Environmental Sciences & Engineering, Government College University Faisalabad, Pakistan, Faisalabad, Pakistan, 2Department of Soil Sciences & Soil Water Conservation, PMAS Arid Agricultural University Rawalpindi, Pakistan , Rawalpindi, Pakistan , 3Department of Agronomy, The University of Agriculture Peshawar, Pakistan , Peshawar, Pakistan
Biochar is a carbon rich product derived from pyrolysis of organic material which improves soil biogeochemical properties and crop production. This incubation study investigated the effects of corncob-derived biochar on native and fresh organic matter (corncob residue) decomposition in nutrient poor Aridisol. The surface soil (0-15 cm layer; <0.1% organic matter) used in the experiment was collected form an agricultural field under wheat cultivation. The treatments included: 1) unamended control, 2) residue (2% w/w), 3) biochar (2% w/w), and 4) residue + biochar (1% each, w/w). Rate of biochar and corncob residue application either alone or combined was equivalent to 45 tons/ha. Each treatment was replicated four times and microcosms were incubated in an incubator following completely randomized design (CRD) at 70% water holding capacity and 25 °C for 54 days. Soil C mineralization was quantified by measuring soil respiration. At the end of the experiment, soil samples were analyzed for soil C and N mineralization indicators, and some physico-chemical properties. Biochar reduced decomposition of fresh organic matter and decreased cumulative respiration by inducing negative priming effect. Decrease in C mineralization in biochar amended soil could be due to the strong adsorption of soluble soil C, nutrients and microbes on the surface of biochar resulting in enhanced C use efficiency and reduction in activity of C mineralization enzymes. Another mechanism for the reduced rate of C mineralization could be CO₂ adsorption on biochar surface as carbonate. The decrease in mineral N after biochar incorporation could indicate that organic N was assimilated into microbial biomass rather than being mineralized. In conclusion, biochar could decrease C mineralization but enhanced microbial C use efficiency. It, therefore, offers an important management strategy to improve C sequestration in nutrient and organic C deficient alkaline soil by altering mineral associated & particulate organic matter.
Dr. Muhammad Riaz is working as an Associate Professor in the Department of Environmental Sciences & Engineering, Government College University Faisalabad (GCUF), Pakistan. He earned his PhD in Environmental Sciences from the University of York, UK. His research is mainly focused on soil biogeochemistry, CNP cycling in agroecosystems, biochar as a tool for soil C sequestration and soil quality management, and dynamics of soil organic matter cycling and recycling in semi-arid and arid agroecosystems.