黄河三角洲不同盐度壤土表层水盐关系研究

Study on Surface Water-Salt Relationship of Loam with Different Salinities in Yellow River Delta

为防治黄河三角洲土壤次生盐渍化,通过配制轻度、中度、重度盐渍化程度的壤质土体,进行土壤水盐关系试验,利用经典统计分析、线性回归分析、Origin图表分析等方法,探讨了在加水升盐、淋水降盐、蒸发返盐过程中土壤水盐之间的相互关系,在此基础上,通过测算土体田间持水量估算了大田降盐灌水参数。结果表明,(1)升盐过程中,土壤表层水盐呈现正向线性关系,含水率的增加对含盐量较高的土体影响较显著,高水高盐环境下的水盐相关性高于低水低盐环境下的水盐相关性;(2)降盐过程中,土壤表层水盐呈现负向线性关系,达到田间持水量后再注入2%的水时,各土体内盐分下降的幅度最大,随后趋于平缓;(3)当体积含水率达到20%时,土体达到田间持水量,每667 m^(2)农田灌入约6.6 m^(3)水时,中度盐渍化土降为轻度盐渍化;灌入约7.8 m^(3)水时,重度盐渍化土降为轻度盐渍化;(4)自然蒸发情况下,重度盐渍土体返盐速率明显快于中度盐渍土。

In order to prevent soil secondary salinization,in the Yellow River Delta,this paper prepared loam soil with mild,moderate and severe salinization,and carried out the experiment of soil water-salt relationship,the relationship between soil water and salt in the process of adding water to raise salt,pouring water to lower salt and evaporating back salt was discussed by using the methods of classical statistical analysis,regression analysis analysis and Origin chart analysis,the field water holding capacity of soil was calculated and converted into field water holding capacity,and the parameters of salt-reducing irrigation were estimated.The results showed that:(1)In the process of salt rising,there was a positive linear relationship between water and salt in the surface layer of soil,and the increase of water content had a significant effect on the soil with higher salt content,the water-salt correlation in the high water and high salt environment was higher than that in the low water and low salt environment;(2)The water-salt correlation in the soil surface showed a negative linear relationship in the process of salt reduction;(3)When the volume water content reached 20%,the soil reached the field water holding capacity,which was converted to about 6.6 m3 water per 667 m2 farmland,the moderately salinized soil becomed slightly salinized;when about 7.8 m3 of water was injected,the severely salinized soil was reduced to slightly salinized soil;(4)Under the condition of natural evaporation,the rate of return salinization of heavy salinized soil was obviously faster than that of moderate salinized soil.