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

Change in land use can alter soil chemical properties and microbial community composition that are greatly associated with the soil quality and health. In South Korea, large numbers of paddy areas have recently converted to upland fields, and various types of land management are conducting to improve the soil fertility and productivity. However, lack of studies have been reported to seek out proper soil management in uplands converted from paddies so far, and also there are few studies about soil microbial community and its relationship with soil properties in the agricultural lands. This study aimed to investigate differences in soil chemistry and microbial community structure between upland converted from paddy and existing soybean upland and to evaluate their changes according to the cultivation periods following the land use conversion. As a result, the soil chemistry and microbial community composition varied significantly with various fertilizer treatments including non-fertilizer (NF), inorganic fertilizer (NPK), and a mixture of NPK and compost (NPKC). Additionally, variations in the chemical and biological parameters were influenced by the period of farming practices following the land use conversion. Overall, the major soil factors related to the change in soil chemistry by different fertilizer treatments; in particular, organic matter (OM), available phosphate (Av. P₂O₅), and exchangeable K (Ex. K). It is likely that such differences in the chemical parameters were closely linked to the change in soil redox condition after the conversion to uplands. This may affect the formation of soil microbial community structure, directly or indirectly, throughout the whole treatments of this study. The indices of abundance/richness including abundance-based coverage estimator (ACE) and Chao and alpha diversity including Shannon and non-parametric Shannon (Np-Shannon) were in the order NPCK > NPK > NF, consistently. Also, the microbial community structure at phylum level was observed in the order of Proteobacteria > Acidobacteria > Actinobacteria > Chloroflexi > Verrucomicrobia > Planctomycetes > Firmicutes in the soils of this study. Among the bacterial phyla, Acidobacteria and Bacteroidetes that are aerobic and play a key role in nutrient cycling were found to increase their population as the cultivation period increased after the conversion of land use. However, despite the increase in such beneficial bacteria abundance related to nutrient cycling through the soil management for 3 years, it seems that the low availability of P in soils of all treatments and severe climatic conditions adversely affected the soybean yield. Therefore, in order to maximize the soil fertility and productivity after conversion from paddies to uplands, it is important to find out proper soil management approaches for each cropland. Also, such land management should be continuously implemented by identifying environmental factors and microbial community structures that are largely related to soil quality and health improvement.

RDA of bacterial community and chemical properties of soils with different fertilizer treatments for 3 years after conversion from paddy to upland.