Characteristics of Inorganic Nitrogen and Phosphorus Runoff under Different Water Management Treatments in Irrigated Paddy Fields
2017
Lee, K.B., National Institute of Crop Science, RDA, Muan, Republic of Korea | Yu, G.D., National Institute of Crop Science, RDA, Muan, Republic of Korea | Lee, K.D., National Institute of Agricultural Sciences, RDA, Wanju, Republic of Korea | Park, C.W., National Institute of Agricultural Sciences, RDA, Wanju, Republic of Korea | Lee, D.B., National Institute of Agricultural Sciences, RDA, Wanju, Republic of Korea
The objective of this study was to quantify and characterize the inorganic nitrogen and phosphorus outflow loading from different water managements in paddy fields. We investigated the NO3-N, NH4-N, and PO4 in runoff from paddy fields in Iksan. The three different water management treatments were conventional continuous irrigation at 4 and 8 cm water levels, and intermittent irrigation at a 4 cm water level. The concentration of NO3-N at the early growth stage in surface water was 6.11 mg L-¹, and then it gradually decreased. The downward curve increased slightly with additional nitrogen fertilization at the panicle initiation stage, and then it continued to decrease. The NH4-N concentration was 5.26 mg L-¹, and that of PO4 was 0.70 mg L-¹ at the early growth stage. However, the concentration of NO3-N peaked at 8.79 mg L-¹ directly after transplantation and then decreased rapidly throughout the growing season. The amount of NH4-N runoff was 1.86 kg ha-¹ in the plot with intermittent irrigation, and 2.0 kg ha-¹ and 2.1 kg ha-¹ in the plots with water depths of 4 and 8 cm, respectively. The NO3-N runoff was 7.43 kg ha-¹ in the plot with intermittent irrigation, 8.62 kg ha-¹ in the plot with a water depth of 4 cm, and 10.25 kg ha-¹ in the plot with a water depth of 8 cm. In addition, the PO4 runoff was 0.42 kg ha-¹ in the plot with intermittent irrigation, 0.48 and 0.55 kg ha-¹ in the plots with water depths of 4 and 8 cm, respectively. The saving effect of irrigation water was 28.5% than that of conventional water management treatments, and the amount of nitrogen runoff was decreased by 18.5% with intermittent irrigation. However, the phosphorus runoff was not different between the different water management treatments in paddy fields.
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