陇东黄土高原苜蓿草地土壤水分消耗及水分生态效应（英）

黄土高原地区土壤干化导致林草植被大面积衰退，研究苜蓿草地土壤水分消耗规律对该区农业持续发展及生态环境恢复具有重要的理论意义。该文研究了黄土高原地区不同生长年限苜蓿草地1 000 cm土层土壤水分的变化特征及其对土壤水分生态环境的影响。结果表明：在0～1 000 cm土层，4年、6年生苜蓿草地土壤水分条件最好；12年、18年、26年生苜蓿草地土壤水分条件最差。在黄土高原地区，苜蓿地土壤干层出现的区域及发生的程度不同。4年、6年、8年生苜蓿草地，对土壤水分生态环境不会产生不利影响；12年、18年、26年生苜蓿草地，对土壤水分生态环境产生深刻负面影响。研究表明在陇东黄土高原地区苜蓿生长6 a后，应实施粮草轮作，以恢复土壤水分，持续提高土地生产力水平。

Soil moisture consumption and ecological effects in alfalfa grasslands in Longdong area of Loess Plateau

Soil desiccation is the most serious problem, which leads to widespread land degradation in the Loess Plateau of China. Hence, it has important theoretical significance to study the consumption patterns of soil moisture in alfalfa grasslands so as to realize sustainable agricultural development and ecological environment rehabilitation in the entire Loess Plateau. Changes of soil moisture characteristics in 0-1000 cm soil and the effects on ecological environment of soil moisture in alfalfa grasslands were investigated. The results showed that: (1) In 0-1000 cm soil, the grasslands with alfalfa growing for four years, six years had the best soil moisture conditions, while the grasslands with alfalfa growing for twelve years, eighteen years and twenty-six years had the poorest soil moisture conditions. (2) In the Loess Plateau, emerging regional and extent of dry soil layer differed in alfalfa grasslands. (3) The grasslands with alfalfa growing for four years, six years and eight years did not produced unfavorable impacts on ecological environments of soil moisture, but the grasslands with alfalfa growing for twelve years, eighteen years and twenty six years had a profound negative impact on ecological environments of soil moisture. The study considered that in Longdong Loess Plateau, grass-crop rotation should be practiced to recover soil moisture so as continue to raise land productivity, after alfalfa grew for more than six years.