Factors affecting spatial pattern of groundwater hydrochemical variables and nitrate in agricultural region of Korea

초록

The overuse of fertilizers for high yields in agricultural production increases the leaching problem particularly in areas affected by heavy monsoon precipitations in Republic of Korea. The extent of leaching depends on various factors such as rate of monsoon precipitation, agricultural management practices, land use, soil properties, topographic features, and hydrochemistry. We studied spatial variations based on temporal fluctuations of groundwater level below the ground surface, pH, electrical conductivity (EC), and nitrate (NO3) from year 2011 to 2014 in 70 groundwater wells in agricultural region of Korea. We found that groundwater level deepening across the studied period in agricultural area. Low pH (5.50-6.50) gradually vanished in year 2014 and high pH (8.51-9.50) appeared in the same year. Variations in the EC values shifted from high range EC (>500 mu S/cm) to lower range (<100 mu S/cm) from 2011 to 2014. Similar to spatial pattern of groundwater EC and contrary to pH, the high values (>50 mg/L) for groundwater NO3 which appeared in the start of the study period, got vanished at the end of the study period. These findings are attributed to improved agricultural practices and change in land use pattern from vegetables to orchards and ginseng fields which do not require excessive fertilizer application.

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