Korean Journal of Soil Science and FertilizerISSN:0367-6315(Print) 2288-2162(Online)한국토양비료학회

The intrinsic characteristics of soil can be altered by purpose of land use and its history, which would determine the quality and health of the soil. In South Korea, along with the trend of decreasing agricultural land area, land use conversion from paddies to uplands is being promoted to alleviate the oversupply of rice and to improve the self-sufficiency rate of field crops. So far, in order to increase the productivity of crops after land use conversion, various types of soil management have been applied, focusing mostly on chemical properties related to soil fertility rather than biological properties related to soil health. This study was conducted to compare the difference in soil biochemistry of uplands with different periods of land use conversion from paddies, and to investigate the interrelationship between these soil characteristics. In general, there were significant differences in chemical parameters of soils according to the period of soybean cultivation (2, 4, and 10 years) after land use conversion of paddy fields. In Andong region, soil pH, organic matter (OM), total nitrogen (T-N), available phosphate (Av. P), and exchangeable potassium (Ex. K) increased with increase in the period of the land use conversion. Similarly, pH, Av. P, Ex. K, Ex. Ca, Ex. Mg and Org. P were the highest in the 10-year soybean growing uplands. Like the soil chemistry, soil microbial enzyme activities including dehydrogenase (DHA), β-glucosidase (BG), alkaline phosphatase (ALP), and arylsulfatase (AS) differed by the period of agricultural practices since the land use conversion but varying with study areas. Principle component analysis (PCA) showed clear separations of the upland soils with different periods of farming since land use conversion that is highly influenced by soil OM and pH as well as BG and ALP in both areas. With comprehensive interpretation of all results in this study, we predicted that, in both areas, applications of inorganic and organic fertilizers have been continuously performed, thereby improving the soil productivity of uplands converted from paddies following the land use conversion. As such, improved quality of the soils by the land managements could result in a positive effect on the soil health, by enhancing the overall microbial abundance as well as stimulating their functions such as nutrient cycling.

PCA of the biochemical properties of soils with different periods of agricultural practice after conversion from paddies to uplands.