Aggregate Associated Carbon, Aggregation and Storage of Soil Organic Carbon Respond to Organic and Synthetic Fertilizers in Cereal Systems: A Review

Soil organic carbon (SOC) and its labile fractions are strong determinants of soil chemical, physical, and biological properties and the recycling of crop residues is an important factor affecting soil organic matter levels and soil quality. This collected review literature specifically aims on soil fertility related to aggregate associated carbon, aggregate-size distribution, aggregation and storage of soil organic carbon trends and their respond towards organic and synthetic fertilizers and also understanding of the effects of diverse soil management regimes on SOC sequestration in cereal systems. Several studies results showed that, with the exception of unfertilized control (CK) and nitrogen fertilizer (N) treatment, the concentration of SOCs in the soil layer 0-20 cm increased. The SOC concentration and storage to depths of 60 cm is significantly affected by long-term fertilization. SOC concentrations and stocks below 60 cm for all treatments were statistically insignificant. The degree of SOC was higher in farmyard manure plus N and P fertilizers (NP+FYM) at different depths, compared with CK, at 0-60 cm soil profile and followed by straw plus N and P fertilizers (NP+S) respectively. SOC storage in NP+FYM, NP+S, FYM and nitrogen and phosphorus (NP) fertilizers treatments increased by 41.3%, 32.9%, 28.1% and 17.9% respectively compared to CK treatment in 0–60 cm. Organic manure plus inorganic fertilizer application also increased organic carbon pools of the labile soil at depths of 0–60 cm. Particulate organic carbon (POC), dissolved organic carbon (DOC) and microbial biomass carbon (MBC) average concentration in organic manure plus inorganic fertilizer treatments (NP+S and NP+FYM) increased by 64.9–91.9 percent, 42.5–56.9 percent and 74.7–99.4 percent over CK treatment. The average control treatment SOC concentration was 0.54 percent, which increased to 0.65 percent in RDF treatment and 0.82 percent in RDF+FYM treatment and increased enzyme activity, potentially affecting soil nutrient dynamics in field conditions. The RDF+FYM treatment sequestered 0.28 Mg C ha-1 yr-1 compared with the control treatment while the NPK treatment sequestered 0.13 Mg C ha-1 yr-1 respectively. It can be concluded that long-term additions of organic manure have the most beneficial effects on the production of carbon pools, improve the availability of SOCs and also enhance C sequestration in soils.