Location: National Soil Erosion ResearchTitle: Aggregate stability and water retention near saturation characteristics as affected by soil texture, aggregate size and polyacrylamide application
|MAMEDOV, AMRAKH - Selcuk University|
|Huang, Chi Hua|
|ALIEV, FAZIL - Virginia Commonwealth University|
|LEVY, GUY - Agricultural Research Organization Of Israel|
Submitted to: Land Degradation and Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2016
Publication Date: 5/16/2016
Citation: Mamedov, A.I., Huang, C., Aliev, F.A., Levy, G.J. 2016. Aggregate stability and water retention near saturation characteristics as affected by soil texture, aggregate size and polyacrylamide application. Land Degradation and Development. 28:543-552.
Interpretive Summary: In the soil, smaller particles, i.e., clays and silts, tend to cluster together and form soil aggregates which are the primary sources for water holding and nutrient retention. Therefore, the stability of soil aggregates has been recognized as the primary factor in determining the quality of a soil. In this research, we measured the aggregate stability of three different aggregate sizes from four different soils, ranging in texture from loamy to clays. We also studied the changes in aggregate stability after adding polyacrylamide (PAM), a commonly-used soil stabilizer. In general, aggregate stability increases as the clay content is increased. We also found that PAM improved the stability in large aggregates, but totally ineffective in smaller aggregates. In other words, how well a soil will respond to PAM treatment depends on its aggregate size distribution. Therefore, in planning a soil improvement project, it is important to know the soil properties, such as its texture and aggregate stability, to have an effective treatment scheme.
Technical Abstract: Understanding the effects of soil intrinsic properties and extrinsic conditions on aggregate stability is essential for the development of effective soil and water conservation practices. Our objective was to evaluate the combined role of soil texture, aggregate size and application of a stabilizing agent on aggregate and structure stability indices (composite structure index [SI], the a and n parameters of the VG model and the S-index) by employing the high energy (0–5·0 J kg_1) moisture characteristic (HEMC) method. We used aggregates of three sizes (0·25–0·5, 0·5–1·0 and 1·0–2·0mm) from four semi-arid soils treated with polyacrylamide (PAM). An increase in SI was associated with the increase in clay content, aggregate size and PAM application. The value of a increased with the increase in aggregate size and with PAM application but was not affected by soil texture. For each aggregate size, a unique exponential type relationship existed between SI and a. The value of n and the S-index tended, generally, to decrease with the increase in PAM application; however, an increase in aggregate size had an inconsistent effect on these two indices. The relationship between SI and n or the S-index could not be generalized. Our results suggest that (i) the effects of PAM on aggregate stability are not trivial, and its application as a soil conservation tool should consider field soil condition, and (ii) a, n and S-index cannot replace the SI as a solid measure for aggregate stability and soil structure firmness when assessing soil conservation practices.