Alternate Drying and Rewetting Effects on Chemical and Physical Properties and Moisture-Salinity Relationships of a Histosol
1978
Giskin, M. | Levin, I.
Under field conditions, cycles of drying and wetting take place naturally. Extreme fluctuations in the moisture content of Histosols have been reported to affect a number of soil processes and constituents. The purpose of the study was to investigate the possible influences on soil management of changes in chemical and physical properties resulting from a Histosol being carried through several successive dryings and wettings. Soil from the 0 to 30 cm layer of a low moor Histosol with a pH of 7.6 and organic matter content of 55.3% was used. The soil was put through three successive cycles of air-drying and rewetting; subsamples were removed at each stage and physical and chemical determinations were carried out. The saturation percentage of the field sample decreased from 95.9 to 87.3% after the third drying cycle. The elecrtical conductivity of the saturation extract decreased at each drying stage, due to the large differences in the nitrate content between the dry and wet stages (8 vs. 380 ppm). Moisture retention curve data showed 5% difference in available water between the moist field sample and the same sample after air-drying. The data show that laboratory measurements of soil-water relations for a Histosol change with time, i.e., with each exposure to drying and rewetting prior to sampling. This information will have a direct bearing on the management of a Histosol, i.e., when determining the amount of irrigation waters to be applied.
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