加硒再生水不同灌溉方式下土壤硒的空间分布及影响因素分析

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

【目的】研究加硒再生水滴灌与畦灌对土壤中硒的空间分布及与土壤理化性质的相关性。【方法】采用盆栽试验水肥一体加硒法,设置了高低2个加硒量(H:4 mg/kg,L:1 mg/kg)和3种灌水方式(2D:2 L/h滴灌,4D:4 L/h滴灌,Q:小畦灌),并以不加硒作为对照,试验共7个处理(2DL、4DL、QL、2DH、4DH、QH、CK不加硒),研究了在再生水滴灌和畦灌条件下,添加不同量的外源硒对土壤硒空间累积分布的影响。【结果】除不加硒处理(CK)外,其他各处理0~10 cm土壤含硒量显著高于10~20 cm土壤含硒量(P<0.05);在距滴头水平距离10 cm处的土壤,低加硒量的2DL、4DL、QL处理土壤含硒量比CK分别提升了1.04、1.21、0.83倍,高加硒量的2DH、4DH、QH处理比CK土壤含硒量分别提升了2.03、2.31、2.48倍;2 L/h滴灌的2DL、2DH处理土壤含硒量的等值线图呈“窄深”型,4 L/h滴灌的4DL、4DH处理土壤含硒量呈“浅宽”型,小畦灌的QL处理下呈“浅宽”型,小畦灌的QH处理下呈“近水平等高线型”。【结论】加硒灌溉显著提升0~10 cm土层土壤含硒量,且外源硒施加量为1 mg/kg和4mg/kg时,0~10 cm土层处于中硒与富硒量值区间内;2 L/h加硒滴灌,相较于畦灌更有利于外源硒在0~10 cm土层植物根系层附近的累积,同时减少外源硒的深层淋洗;0~10cm土层土壤有机质质量分数和含水率与土壤含硒量显著正相关,土壤电导率与土壤含硒量呈负相关关系。

【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.