Spatial Distribution of Added Selenium in Soil as Affected by Different Irrigations Using Reclaimed Water

【Background】 Selenium is a crop nutrient but scarce in many soils. One solution is to add selenium with irrigation water to the soil. In this paper we investigated experimentally spatial accumulation and distribution of added selenium and is correlation with physical and chemical properties of soil under different irrigations using reclaimed water. 【Method】 The experiment was conducted in pots. It consisted of two selenium additions: 4 mg/kg and 1 mg/kg (L), with each addition having three irrigation amounts (or methods). 2 L/h drip irrigation (2D), 4 L/h drip irrigation (4D), and border irrigation (S). Without selenium addition was taken as the control (CK). We measured accumulation and distribution of the added selenium in each pot. 【Result】 Except in CK, selenium content in the top 0~10 cm soil was significantly higher than that in the 10~20 cm soil (P<0.05). For L treatment, the selenium content in the soil 10 cm away from the emitter under 2D, 4D and S increased by 1.04, 1.21 and 0.83, respectively, while for H treatment these increased by 2.03, 2.31 and 2.48 times, respectively, compared to CK. The contour of selenium content in 2D+L and 2D+H showed a "narrow-deep" type, while in 4D+L and 4D+H and Q+L, it showed a “pudgy” type. Selenium content in Q+H showed a “near horizontal contour” distribution. 【Conclusion】 Adding selenium with irrigation water increased selenium content in the 0~10 cm soil, with the content increasing with the application amount. Compared with border irrigation, drip irrigation increased selenium accumulation in the root zone - the top 0~10 cm of soil. Soil selenium content was positively correlated with organic matter and water content in the 0~10 cm soil, but negatively correlated to soil conductivity, both at significant levels.