Characteristics of Nutrient Concentrations in Groundwater under Paddy and Upland Fields
2011
Jang, H., Korea Water Resources Corporation, Yeoju, Republic of Korea | Kim, J.S., Chungbuk National University, Cheongju, Republic of Korea | Kim, Y.H., Chungbuk National University, Cheongju, Republic of Korea | Song, C.M., The Policy Council for the PALDANG Watershed, Yangpyeong, Republic of Korea
The objective of this study was to compare concentrations of nutrients such as total nitrogen (TN), nitrate nitrogen (NO₃-N) total phosphorous (TP), and phosphate phosphorous (PO₄-P) in groundwater under paddy and upland fields, and surface water recharging from a rural mixed land-use watershed. Chinese cabbage and hot pepper were cultivated on the upland field plot. The TN concentrations in upland groundwater showed double peaks (4.7, 4.3 mg/L, respectively) in April 2009 shortly after fertilizer application, indicating that TN concentrations are greatly influenced by fertilization. However, the TN concentrations in paddy groundwater were always lower than 2.0 mg/L irrespective of fertilization. Whereas the mean concentrations of TN and NO₃-N in upland groundwater significantly (p less than 0.05) higher than those in surface water, the mean concentrations of TP and PO₄-P in upland groundwater were significantly lower than those in surface water. On the other hand, the mean concentrations of TN, NO₃-N, TP and PO₄-P in paddy groudwater were significantly (p less than 0.05) lower than those in surface water. The TN concentrations in upland groundwater were generally higher than those in surface water during early April to early December due to the effect of fertilization, but vice versa in the other periods. In contrast, the TP concentrations in upland groundwater were always lower than those in surface water due to the sorption of inorganic phosphorous by soil. Moreover, the TN and TP concentrations in paddy groundwater were always lower than those in surface water, and therefore paddy groundwater may dilute nutrient concentrations in surface water when paddy groundwater and surface water mix.
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