Estimating Air Porosity and Available Water Capacity from Soil Morphology1
- J. A. McKeague2
Field guidelines based on soil morphology and calibrated against measured values were developed for estimating air porosity (AP, volume percent air-filled pores at 5 kPa) and available water capacity (AWC, volume percent water retained between 5 and 1500 kPa). The guidelines were tested by estimating and subsequently measuring these properties of 24 soil horizons. The mean of the absolute differences between estimated and measured AP and AWC were 3.7 and 4.5% respectively. AP for the 24 horizons ranged from 3 to 30% and AWC from 14 to 39%. In view of the magnitude of local soil variability, the discrepancies in measured values of AP and AWC by different methods and the lack of standard methods, the estimates are shown to be useful. Estimation of air-water regime properties of soils from well-calibrated morphological guidelines is recommended for use in soil survey and in research on effects of management on soil physical properties.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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