Which Soil has the Highest Plant Available Water Capacity

The plant available water capacity (PAWC) of soil is defined as the amount of water that is held in soil that is available to plants for uptake. It is a crucial parameter for crop growth and can vary depending on the type of soil. In this article, we will discuss which soil has the highest plant available water capacity.

What is the Plant Available Water Capacity

The Plant Available Water Capacity (PAWC) is the total amount of water that is held by soil that can easily be extracted by a plant for use in growth and development. PAWC plays a vital role in the water balance of soil, as it is the difference between the maximum amount of soil water that can be held and the permanent wilting point, the threshold of soil moisture below which plants are no longer able to extract water. PAWC is an essential factor for estimating crop water requirements and managing irrigation.

Factors Affecting Plant Available Water Capacity

Various factors affect the plant available water capacity of soil, including texture, structure, organic matter content, and clay content. Soil texture plays a significant role in the ability of soil to hold water, with clay soils having higher water holding capacity than sand or loam soils. Structure and organic matter can also affect the water-holding capacity of soil by improving soil aggregation or increasing soil porosity. The ability of soils to manage water is also influenced by climate; for example, soils in arid regions have lower water availability than those in humid climates.

Soil Types with Highest PAWC

Studies have shown that clay loam soils generally have the highest PAWC, compared to other soil types. Clay loam soils have a high clay content (between 20-30%), which gives them high water-holding capacity. In comparison, sandy soils have low water-holding capacity due to their lower ability to retain water. Clay soils are dense and compact, which limits their ability to infiltrate water, but it is good at retaining water. Soils with high organic matter content also have high PAWC as organic matter improves soil structure and increases soil porosity. This helps soil to store more water by increasing its infiltration capacity.

Conclusion

The Plant Available Water Capacity is an essential factor for understanding soil fertility and agricultural productivity. The soil type, structure, organic matter content, and climate are the key determinants of the PAWC of soil. Studies show that clay loam soil has the highest PAWC, making it the most ideal soil type for agriculture. The high-water holding capacity of clay loam soils makes it suitable for crops, especially during dry spells, as it can retain water for a more extended period compared to other soil types.