Chemical and hydrological controls on salt accumulation in irrigated soils of southwestern U.S
Chemical and hydrological controls on salt accumulation in irrigated soils of southwestern U.S
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DOI：
10.1016/j.geoderma.2021.114976
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发表时间：
2021-06
期刊：
影响因子：
6.1
通讯作者：
A. Ortiz;Lixin Jin
中科院分区：
文献类型：
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作者：
A. Ortiz;Lixin Jin
土壤盐渍化是一个全球性问题，影响约10%的农业土壤，特别是在灌溉干旱地区。本研究量化了洪水灌溉和土壤肥料/改良剂与大气沉降的盐负荷，研究了溶质运移和盐积累的控制，并评估了石膏应用在改善美国西南部干旱地区土壤碱度方面的有效性。研究地点包括该地区主要作物的一个自然地点和两个农业地点，一个山核桃果园和德克萨斯州埃尔帕索附近的苜蓿地。农田土壤的盐分负荷率主要受灌溉沃茨的数量和质量的影响，而不是受沙尘的影响。灌溉沃茨的盐分负荷估计为~ 306 g Na+m− 2 yr −1、129 g Ca 2 +m− 2 yr −1、361 g Cl−m− 2 yr −1、419 g SO 42 −m− 2 yr −1和284 g HCO 3 −m− 2 yr −1，其次是土壤改良剂。而农业土壤中的粉尘和肥料含量可以忽略不计。土壤质地的变异性在物理上控制着水分运动和溶质运移;灌溉后，较粗的土壤比较细的土壤保留的水分明显较少（p < 0.005），有利于盐的淋溶。在低渗透层附近，盐分积累较多。一些土壤在耕作仅90年后就已接近盐度阈值。由于科罗拉多州降雪量减少，预计格兰德河流量将减少，从而导致更多含盐量较高的地下水被使用。如果地下水是唯一的水源，盐的负荷率几乎会增加一倍。土壤改良剂暂时降低土壤碱度引起的高Na+浓度的灌溉水。每年都需要施用它们来防止土壤分散，改善渗透，并阻止更快的盐积累。这项研究突出了美国西南部格兰德河流域和其他灌溉旱地面临的挑战。
Soil salinization is a global problem affecting approximately 10% of agricultural soils, particularly in irrigated aridlands. This study quantified salt-loading by flood irrigation and soil fertilizers/amendments versus atmospheric deposition, studied controls of solute transport and salt buildup, and evaluated the effectiveness of gypsum application in improving soil sodicity in the arid southwestern United States. Study sites include one natural site and two agricultural sites in fields of dominant crops of the region, a pecan orchard and an alfalfa field near El Paso, Texas. The salt-loading rate in agricultural soils was dominated by the quantity and quality of irrigation waters rather than by dust. Salt loadings by irrigation waters were estimated ~ 306 g Na+m−2yr−1, 129 g Ca2+m−2yr−1, 361 g Cl−m−2yr−1, 419 g SO42−m−2yr−1, and 284 g HCO3−m−2yr−1, followed by soil amendments. Whereas dust and fertilizer loadings were negligible in agricultural soils. Soil texture variability physically governs water movement and solute transport; coarser soils retained significantly less water than finer soils upon irrigation (p < 0.005) facilitating salt leaching. More salts accumulated around low-permeability layers. Some soils have approached salinity thresholds after only 90 years of cultivation. The Rio Grande river flow is projected to decrease due to reduced snowfall in Colorado, leading to more groundwater of higher salinity, to be used. If ground water were to be the sole water source, the salt loading rate would almost double. Soil amendments temporarily reduce soil sodicity induced by high Na+concentrations in irrigation water. Their application is needed annually to prevent soil dispersion, to improve infiltration, and to stop even faster salt accumulation. This study highlighted the challenges that the Rio Grande valley in southwestern United States and other irrigated drylands are facing.