Soil Water Matric Potential Effects on Aggregate Stability1
- P. B. Francis and
- R. M. Cruse2
The effect of soil water matric potential (ψm) is not considered with most techniques utilized to evaluate aggregate stability. Rather, aggregate stability usually is measured at ψm of 0 Pa or at an unknown ψm. The objective of this study was to determine ψm effects, in the range of 0 to −3,000 Pa, on stability of natural soil aggregates obtained from a fencerow and from plots having a range of management histories. Aggregate stability, considered inversely related to the mass of soil detached by impact of falling water drops, increase markedly as ψm decreased from 0 to −500 Pa. Similar ψm changes at ψm < −500 Pa had smaller effects on aggregate stability. Significant differences in stability of aggregates obtained from plots with different cropping and/or manuring histories, were sometimes undetectable at ψm ≤ −500 Pa but were more consistently detected at ψm = 0 Pa. Data from this study indicate that aggregate stability is very sensitive to ψm, particularly at ψm near zero. Techniques for comparing aggregate stability between soils or soil treatments should ensure equal values of ψm exist for all aggregates. Measurements made over a range of ψm should yield better comparisons of aggregate stability between soils than measurements made at one ψm.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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