添加γ-聚谷氨酸对土壤结构及持水特性的影响

Effects ofγ-PGA on Soil Structure and Water-holding Characteristics

为进一步探究γ-聚谷氨酸在农业方面应用,将不同γ-PGA含量(0,0.1%,0.2%,0.5%,1%)施入无团粒结构的砂壤土与粉壤土中,研究了γ-PGA在土壤物理结构及持水特征方面的作用。结果表明:随γ-PGA含量的增加,同一吸力下土壤持水量增加,VG模型中参数α值均大于对照组,n值递减。γ-PGA添加至1%时,砂壤土中容重降低0.087g/cm3,孔隙度增加3.28%,粉壤土中容重降低0.108g/cm3,孔隙度增加4.08%,添加γ-PGA降低了毛管孔隙比例,提高无效孔隙比例,表明γ-PGA对粉壤土物理特性影响大于砂壤土。饱和含水量与γ-PGA含量呈幂函数正相关,饱和扩散率则呈负相关关系,粉壤土中VG模型参数所计算饱和扩散率与水平入渗法计算值间相对误差值小于10%。除凋萎系数外,γ-PGA对其余土壤水分常数影响显著,均随γ-PGA含量增加而增大。土壤中薄膜水、毛管水比例提高,重力水比例显著下降。γ-PGA含量为1%时,粉壤土中有效水比例为64.83%,砂壤土中仅为56.14%。添加γ-PGA有利于改良土壤内孔隙分布,提高持水能力,防止土壤水分的深层渗漏。

In order to further research the application ofγ-PGA in agriculture,different contents ofγ-PGA（0,0.1%,0.2%,0.5% and 1%）were applied in sandy loam and silty loam without granular structure to study the effects ofγ-PGA on soil physical structure and water retention characteristics.Results showed that：with the increasing ofγ-PGA content,water retention capacity of soil increased under the same absorption force.Values ofαin the VG model were all larger than those in the control group,and n value decreased progressively.When the content ofγ-PGA increased to 1%,the bulk density of sandy loam decreased by 0.087 g/cm3,and the porosity increased by 3.28%;corresponding parameters of silty loam were 0.108 g/cm3 and 4.08%,The addition ofγ-PGA reduced the proportion of capillary pore,and increased the proportion of invalid pore,indicating that effect ofγ-PGA on the physical characteristic of silty loam were greater than those of sandy loam.Power function positive correlation existed between the saturation moisture content and theγ-PGA content,while negative correlation existed between the saturation diffusion rate and theγ-PGA content.The relative error between the saturation diffusion rates calculated by parameters of VG model and horizontal infiltration method was smaller than 10% in silty loam.Except for the wilting coefficient,γ-PGA had significant effects on other soil water constants,wherein the constants increased with the increasing ofγ-PGA content.In the soil,proportions of film water and capillary water increased,whereas the proportion of gravitational water decreased significantly. When theγ-PGA content was 1%,the proportion of available water was 64.83%in silty loam,whereas the value was only 56.14%in sandy loam.Addingγ-PGA was beneficial to improve pore distribution in soil and water retention capacity,and prevent deep seepage of soil moisture.