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

This study aimed to identify the changing trends in the agricultural water quality of the major watersheds in Chungbuk province over a 10-year period ranging from 2007 to 2016. The results of water quality analysis of the study sites revealed that the mean chemical oxygen demand was 3.1 mg L^-1, with the median values being 2.8 mg L^-1. The mean chemical oxygen demand in April, July, and October were 2.9, 3.5, and 2.8 mg L^-1, respectively. The mean chemical oxygen demand values were lower in April and October and slightly higher in July. The mean value of electrical conductivity was 0.19 dS m^-1, and there was no yearly fluctuation. The mean and median values of the Total Nitrogen (T-N) content were 4.2 mg L^-1 and 3.4 mg L^-1, respectively. The mean and median values of the Total Phosphorous (T-P) content were 0.07 mg L^-1 and 0.04 mg L^-1, respectively, and there was a trend of increasing from 2014 to 2016.

Changes in annual water quality index in April, July, and October.