中文摘要：

γ-聚谷氨酸(Poly-γ-glutamic acid,γ-PGA)是一种高分子聚合物,具有超强的吸水能力和生物降解性。为探明γ-PGA在土壤改良方面的应用及对土壤水分运动的影响,该文基于室内垂直一维入渗土柱试验,研究了不同γ-PGA施量配比(0、0.5%、1%、2%、4%)对土壤水分入渗及持水特性的影响。结果表明:与对照组相比,添加4%的γ-PGA的累积入渗量、入渗率和湿润锋分别减少了57.95%、53.89%、59.58%;四种入渗模型参数的模拟结果显示,与对照组相比,随着γ-PGA施量的增加,Kostiakov公式中的经验系数从0.808减小到0.538,经验指数从0.530增大到0.623;Philip入渗公式中的吸渗率从0.704减小到0.292;Green-Ampt公式中,饱和导水率从0.0043减小到0.0011 cm/min,湿润区有效的土壤水扩散率从1.19减小到0.16 cm~2/min,湿润锋处的土壤水吸力无明显变化;垂直一维入渗代数模型中,饱和导水率从0.0044减小到0.001 cm/min,非饱和土壤吸力分配系数和土壤水分特征曲线和非饱和导水率综合形状系数均无明显变化趋势。土壤的持水特性结果表明:随着γ-PGA施量的增加,土壤饱和含水率增加,且与对照相比,表层土壤(0~10 cm土层)的含水率呈显著增加趋势,深层土壤(≥10~40 cm土层)的含水率则呈减小趋势。同时,湿润土层的厚度逐渐减小,说明γ-PGA不仅可增强土壤的持水能力,而且还可改变土壤剖面水分的分布形态,使更多水分蓄积在作物根区土层区域。该研究为γ-PGA的田间土壤改良及应用提供了理论支撑。

英文摘要：

Poly-γ-glutamic acid (γ-PGA) is a natural and water-soluble polymer, which consisted of D-glutamic acid and L-glutamic acid monomer linked by amide bonds between theα-amino and theγ-carboxylic acid functional groups, andγ-PGA is easily biodegradable and its degradation products are nontoxic in the environment. Main ingredients ofγ-PGA are made of protein, minerals and vitamins, and its appearance is white powder. Moreover,γ-PGA has strong water absorption property, which may be able to store water from rainfall and irrigation for enhancing crop growth. In recent years, it is the fact thatγ-PGA is being increasingly used in Agriculture because the enhancement of people's environmental awareness and the requirements of national sustainable development strategy play an important role in application of environmental protection material. An experiment based on the vertical one-dimensional infiltration soil column was conducted to investigate the effect of γ-PGA on soil water infiltration and its water holding characteristics. The soil in the experiment was collected from Changwu Agro-ecological Experiment Station (35°12′N, 107°40′E) in Xi'an, China. The soil passed through a 2 mm sieve, and was dried under normal temperature conditions. The particle size of soil was measured with Mastersizer 2000, and its soil texture was silty loam (3.47%clay, 92.26%silt and 4.27%sand). The soil was mixed with theγ-PGA with different contents (0, 0.5%, 1%, 2%and 4%) respectively. Then, the mixed soil was packed into organic glass column (46 cm in length, 5 cm in diameter) with 5 cm each layer till a depth of 40 cm. The Mariotte lucite was used to provide a free water supply with 1.5 cm in depth on the surface of chamber. The experiment started when the Mariotte lucite was opened. In order to make the head stable, the filter paper was laid at the soil surface. The results indicated that the cumulative infiltration volume, infiltration rate and wetting front reduced from 15.94 to 6.7 cm, from 0.0193 to 0.0089 cm/min and