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Evaluation of Changes in Agricultural Stream Water Quality of Small Watershed in Gyeonggi Province
노안성,박정수,박영수,주옥정,신민우,김민경,최순군 한국토양비료학회 2019 한국토양비료학회지 Vol.52 No.4
This study aimed to identify the changing trends in the agricultural water quality of the major watersheds inGyeonggi 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 3.8 mg L -1 , with the median values being 3.5 mg L -1 . The mean chemical oxygen demand in April, July, and October were 4.7, 3.8, and 3.1 mg L -1 , respectively, and chemical oxygen demand values trended to decrease from April to October. The mean and the median electrical conductivity were 0.22 dS m -1 . The mean electrical conductivity values were slightly higher in April and lower in October, and there was no yearly fluctuation. The mean and median values of the T-N (Total Nitrogen) content were 3.3 mg L -1 and 3.0 mg L -1 , respectively. The mean and median values of the T-P (Total Phosphorous) content were 0.10 mg L -1 and 0.06 mg L -1 , respectively, and there was no tendency to increase or decrease during the April, July and October.
Status and Changes in Chemical Properties of Paddy Soil in Gyeonggi Province
노안성,박정수,김유학,강성수 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.5
The chemical properties of paddy fields in Gyeonggi province were monitored every 4 years from 1999 to 2015 in order to provide basic information for soil fertility management of paddy fields. In 2015, the soil chemical properties of paddy fields were 5.9 in pH, 23 g kg-1 in organic matter (OM), and 84 mg kg-1 in available phosphate (Avail. P2O5). Exchangeable (Exch.) potassium (K), calcium (Ca) and magnesium (Mg) were 0.30, 5.1 and 1.3 cmolc kg-1, respectively, and available silicate (Avail. SiO2) was 129 mg kg-1. In the long-term analysis, the contents of Avail. SiO2, Exch. Ca and pH of paddy soils showed increasing tendency. However, Avail. P2O5 and Exch. K tended to decrease, and there were no significant changes in the contents of OM and Exch. Mg. Paddy soil within appropriate pH range increased from 44% in 1999 to 76% in 2003, 84% in 2007, 63% in 2011, and 80% in 2015. But soil within appropriate range of Exch. Ca tended to decrease, showing 36% in 1999, 42% in 2003, 38% in 2007, 37% in 2011 and 32% in 2015. In case of Avail. SiO2, soil within appropriate range increased from 14% in 1999 to 17% in 2003, 18% in 2007, 16% in 2011, and 31% in 2015. As a result, paddy fields with less in nutrient level need to be more fertilized based on soil analysis. And the application of silicate fertilizer is strongly recommended to those of paddy fields in need. Also soil management such as the cultivation of green manure crop or application of rice straw will be necessary to increase the organic matter content of paddy soil.