Correlation between Carbon dioxide Evolution and Biological Quality Index of Long-term Nutrient Management Adopted Soils

Abstract

Soil respiration in terms of carbon dioxide (CO 2) evolution is a potential biological indicator to assess the soil quality as influenced by different agricultural practices. However, the relation between the CO 2 evolution and the biological attributes of soil is a multitude and hence less resolved. The purpose of the study is to relate the measured CO 2 values with the biological quality indicators of the soil. Four long-term nutrient management treatments (organic manure amended, OM, integrated nutrient management enforced, INM, synthetic fertilizer applied, IC, and unfertilized control, Control) from 100-years old permanent manurial experiment was used for this study. The soils were analyzed for soil organic carbon, microbial biomass carbon, labile carbon, protein index, dehydrogenase activity, and substrate-induced respiration and calculated the soil biological quality index (SBQI) by quadrantplot method. All the soils were measured for the flush of CO 2 immediately after wetting the dry soil by three methods viz., alkali trap method, infra-red probe-based flux apparatus, and multi-gas analyzer. The results revealed that INM had a positive influence to improve all the six biological attributes followed by OM, while the IC and Control had at par levels of all the assessed variables. The SBQI also has high resolution to discriminate against the soils and INM > OM > IC ≈ Control is the order being observed. The CO 2 evolved from these four soils had a strong positive correlation with all the assessed biological health indicators. The regression analysis revealed that SBQI had a significant positive relation with alkali trap CO 2 (R 2 0.82), flux CO 2 (R 2 0.75), and multi-gas analyzer CO 2 (R 2 0.79). The present results suggest that analyzing CO 2 evolution could be a simple method to relate the overall biological quality of the soil. Hence, developing a simple tool to measure the soil CO 2 evolution could help the farmers to know the biological quality of the soil .