Stability of Arable Soil Aggregates: Experimental Determination and Normative Characteristics

Abstract

Soil stability in modern soil physics is divided into two directions: water stability and resistance to mechanical influences (compression, wedging). Both soil properties in water-saturated soil are based on the rupture of intra-aggregate interparticle bonds, however, no standard physically justified values have been proposed to characterize the stability of aggregates. The purpose of the article is to substantiate the physical concept of stability of soil aggregates and to propose a single methodological method for quantifying stability as a normative soil characteristic. A high-performance method has been developed based on the dissection of linearly arranged water-saturated aggregates using blades under controlled load. The main stages of the technique are vacuuming of aggregates to eliminate the uncontrolled influence of trapped air, saturation of aggregates in vacuum with water and subsequent determination of the aggregates stability to penetration of blades. Experimental stability values (mN/aggregate) were obtained for 17 soils, which made it possible to form normative ranges for mountainous arable heavy loamy soils: sod-podzolic – 17–19, gray forest –27–29, chernozems – 34–37 mN/agr and a number of other soils, which makes it possible to apply the obtained value as a soil characteristic of the stability of aggregates. The possibility of using the stability values as a methodological basis for monitoring soil stability and degradation, quantitative directions for assessing the state of physical characteristics of soil aggregates (first their main parameter, their stability) is discussed. Taking into account the highly correlative dependence of the proposed stability characteristic on the water stability values obtained by the Savvinov method (85%) and the high performance of the stability determination method (the proposed method is about 20 times more productive than the Savvinov method), the possibilities of using the method and the obtained values of the stability of aggregates as a general physical characteristic and a separate well for quantifying water stability are discussed.