Comparison Of Chemical Properties And Humified Fractions Of Soil Of Different Land Use From Limpopo Province, South Africa And Jilin Province, China

Changes of land use have an influence on the buildup of soil organic matter. Suggestions have been made on amendments on the different fractions of SOM to be more effectual in indicating differences in soil uses total SOM content for sustainability of agricultural management. Hence it is viable to find ways to sustainably manage the soil for better crop production. This studies objective was to compare the chemical and humic fractions of soils of three different ecosystems:forest, grassland and cultivated land at of two regions with varying climate. The analysis was carried on soils from Limpopo province, South Africa and results were compared to soils from Jilin province, China. Three land-use types, conserved forest (CF), arable land (RCL and BCL) and grassland (RGL and BGL) collected on plots at a soil depth of 0-7.5cm and 7.5-20cm in South Africa, while from China, cultivated land (CK and CS- deep incorporation of corn stover) and grassland (CGL) were collected at depths 0-20cm and 20-40cm, then examined for specific chemical properties. Two soil types:Black (B) soils and red(R) soils where considered in arable, while only black soils for conserved forest. Analyses were carried in the following manner:Humic substances were extracted by NaOH method, purified and then dialysed. Their substances of chemical nature [Humic acids (HAs), Fulvic acids (FAs), Humin (Hu)] on soils of varying land uses were analyzed by elemental composition and Fourier transformed infrared spectroscopy.Results showed that soils type’s had an influence on soil chemical properties and humic substances, black soils portrayed better chemical and humic contents as compared to red soils in both grassland and cultivated soils. Land use and soil depth both had a significant effect on the SOC stock. The C contents of the HA were higher in black soils (BGL>BCL, respectively) than in red soils. O/C and H/C ratios of the HA were slightly higher in RCL. Higher 2920/1720 and 2920/1620 ratio of HA observed BCL>RCL>BGL surface respectively.The study showed conserved forest land soils to contained higher SOC content and HA and FA when compared to grassland and cultivated area. The PQ value for different land uses showed the expression GL>CL>CF. No obvious patterns were observed for different fractions in all land uses. C, H and N contents of the HA in followed the pattern CF>GL>CL respectively. O/C ratios of the HA was slightly higher in CL and the H/C in CF. Higher 2920/1720 and 2920/1620 ratio of HA observed in CL and lowest in CF subsurface.In soils from China, the results showed that grassland had higher humic fractions than cultivated land and the deep incorporation of corn stover a form of SOM amendment had a positive influence on soils SOM, and improved SOC and humic substances. It is encouraged to improve the fertility of soils as a whole. No major changes observed for C, H contents and O/C ratios of the HA between CS and CK treatments with higher N content observed in CK. H/C remained as par following corn stover incorporation. The ratio of 2920/1720 of HA was higher in CK whereas 2920/1620 of HA was higher in corn stover treatment.The comparisons between black soils of different countries, the study showed that soils chemical and humic fractions content varied. For the investigated cultivated and grassland soils, the SOC, HA and Hu and PQ value where higher in soils from South Africa. Regardless of the land use results showed the largest C contents were measured for the Hu, followed by HA and FA. For cultivated soils, higher C and lower H, O contents of HA and H/C ratio where observed in soils from China (CS>CK excluding O contents of HA). While grassland soils from South Africa showed higher O/C and H/C ratios of HA in the surface than in subsurface soils.