Vol. 7, Issue 1 (2019)

Agro-ecosystems play an important role in regulating global changes caused by greenhouse gas emissions. Restoration of soil organic carbon (SOC) in agricultural soils can not only improve soil quality but also influence weather change and agronomic productivity. With about half of its land area under agricultural use, sub -tropical conditions exhibits vast potential for carbon (C) sequestration that needs to be researched. Sub -tropical conditions cropland has experienced SOC change over the past century. The study of SOC dynamics under different bioclimatic conditions and cereal cropping systems can help us to better understand this historical change, current status, the impacts of bioclimatic conditions on SOC and future trends. Nationwide, 67.6% of the national arable land is considered to be in good condition. Appropriate farm management practices should be adopted to improve the poor C balance of the remaining 32.4% of cropland to promote C sequestration.

Although sandy loam soils on most sub -tropical conditions smallholder farms inherently contain a small amount of SOM, large variability in soil productivity exists between adjacent fields or field sections within the same farm. This review study was based on the SOM, a renewable resource, is the driving force behind sustainable crop productivity on depleted sandy loam soils. Organic inputs with a C: N ratio >25 (the bulk of available resources on-farm) contributed significantly to overall particulate organic matter (POM) size in typic ustochrespt soils. The intensity of C management was reflected more in meso- POM (53-250 µm diameter) compared to the macro-POM (250-2000 µm diameter) fraction suggesting that the larger POM fraction has a high turnover and is not protected from degradation. The overall size of the organo-mineral fraction (<53µm diameter) in these soils was small (<250g kg-1 soil) and stable, and was not influenced by quality and quantity of C inputs and time over which they had been applied.