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Since the beginning of agriculture, people have recognized that a sufficient water supply is essential for crop production. The capacity of soil to store and supply water for plant growth is a fundamental agroecosystem service. It also is a soil health indicator. The Soil Science Society of America’s (SSSA) August 1st Soils Matter blog looks at two questions surrounding soil water holding capacity.
Xi Zhang at Louisiana State University – Agricultural Center explains that there are two questions to consider when looking at soil water holding capacity:
(1) What is the capacity of a soil to store water and have it available for plant growth?
(2) Are all soils the same in this capacity or do they behave differently?
When water, either rainfall or irrigation, touches the soil surface, part of the water is lost through surface runoff, and part is lost by evaporation. The remaining water enters the soil profile via infiltration and becomes soil water.
Soil is a mixture of mineral particles, organic matter, and pore space. Depending on the size, number, and continuity of the pores, soil water is retained in or moves downward through the soil and recharges groundwater through the pore space.
From the perspective of plant growth, soil water can be classified into three types:
(1) excess water or gravitational water, (2) available water, and (3) unavailable water.
When all the pores are filled with water, the soil is water-saturated and at its maximum capacity to hold water. This situation usually occurs for a very short period when water is being added. Water will soon drain out of large pores mainly under the gravitational force.
To read the study and the entire blog please visit: https://soilsmatter.wordpress.com/2023/08/01/what-affects-how-well-soil-holds-water/
