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

This study was conducted with the data of monitoring on soil chemical properties of rice paddy soils in Gyeongbuk Province. The selected soil chemical properties were analyzed every 4 year from 1999 to 2015. The soil pH measured in 2015 was higher than pH 6.0, which was 0.3-0.4 pH unit higher than data until 2007 survey year. The mean content of organic matter was greater than 24 g kg-1 since 2003, but 35% of soil samples remained below the recommended level (20-30 g kg^-1) in 2015. The mean concentration of available phosphate was maintained at 40 mg kg^-1 higher than the upper recommendation level (80-120 mg kg^-1), and more than 40% of paddy soils tested were found to have less than the recommendation level during the survey period. The exchangeable K concentration ranged from 0.25 to 0.39 cmolc kg^-1. Exchangeable Ca showed an average at the optimum range (5.0-6.0 cmolc kg^-1) during the monitoring period. Exchangeable Mg decreased linearly (0.02 cmolc kg^-1 year^-1) from 1.55 cmolc kg^-1 as of 1999 to below the lower level of the recommendation range (1.5-2.0 cmolc kg^-1). The amount of available SiO2 was increased significantly from 2011 to over the recommendation level (≥157 mg kg^-1). It was revealed that the soil chemical properties of rice paddy fields was influenced by topology, soil texture, type and region as result of principal component analysis or cluster analysis. Therefore, an assessment on chemical properties of rice paddy soils should be performed to consider various soil physical conditions and agronomic practices such as fertilization, cropping system, and so on. Because of the high variability of nutrient levels across Gyeongbuk Province, nutrient management based on soil fertility test is required by respective farm land unit.

Changes in soil chemical properties of rice paddy soils in Gyeongbuk Province.

†Mean and standard deviation of soil chemical properties are shown. Different letters in a same column indicate a significant difference (Tukey, p < 0.05) between survey years.