Soil Water Retention
The spaces that exist between soil particles, called pores, provide for the passage and/or retention of gasses and moisture within the soil profile. The soil’s ability to retain water is strongly related to particle size; water molecules hold more tightly to the fine particles of a clay soil than to coarser particles of a sandy soil, so clays generally retain more water (Leeper and Uren, 1993). Conversely, sands provide easier passage or transmission of water through the profile. Clay type, organic content and soil structure also influence soil water retention (Charman & Murphy 1977).
The maximum amount of water that a given soil can retain is called field capacity, whereas a soil so dry that plants cannot liberate the remaining moisture from the soil particles is said to be at wilting point (Leeper & Uren 1993). Available water is that which the plants can utilise from the soil within the range of field capacity and wilting point.
The role of soil water retention is profound - its effects are far reaching and relationships are invariably complex. This section focuses on a few key roles and recognises that it is beyond the scope of this discussion to encompass all roles that can be found in the literature.
Read more about this topic: Soil Water (retention)
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“Let the soil squeal I am the biting man
And the velvet dead inch out.”
—Dylan Thomas (1914–1953)
“What’s water but the generated soul?”
—William Butler Yeats (1865–1939)
“Unless a group of workers know their work is under surveillance, that they are being rated as fairly as human beings, with the fallibility that goes with human judgment, can rate them, and that at least an attempt is made to measure their worth to an organization in relative terms, they are likely to sink back on length of service as the sole reason for retention and promotion.”
—Mary Barnett Gilson (1877–?)