Available Water Capacity - Soil Health Nexus

What is Available Water Capacity?

Photo Credit: https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/ nrcs142p2_051279.pdf

Soil Water Holding Capacity is ability of a soil to hold maximum amount of water between field capacity and permanent wilting point moisture levels and is affected by soil texture, organic matter level, porosity and pore sizes.

Available water capacity is the amount of water that a soil can store that is available for use by plants. In general, it is the water held between field capacity and the wilting point.

Plant Available Water is the part of water held between field capacity and permanent wilting point moisture levels. The actual amount of water absorbed by the plants depends upon plant water-use, growth stage and rooting structure and depths.

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Title	Source	Resource type and date	Short Summary
Soil Quality Indicators: Available Water Capacity	USDA	NRCS Fact Sheet Jun 2008	Fact Sheet. Available water capacity is the maximum amount of plant available water a soil can provide. It is an indicator of a soil’s ability to retain water and make it sufficiently available for plant use.
Available Water Capacity	Soilquality.org – NRCS & others	Webpage Sep 2011	The amount of water in soil is based on rainfall amount, what proportion of rain infiltrates into the soil, and the soil’s storage capacity. Available water capacity is the maximum amount of plant available water a soil can provide. It is an indicator of a soil’s ability to retain water and make it sufficiently available for plant use.
Soil Quality Resource Concerns: Available Water Capacity	USDA – NRCS	NRCS Fact Sheet Jan 1998	Available water capacity is the amount of water that a soil can store that is available for use by plants.
Rainfall simulator – soil health demonstration	Michigan State University	Video Demonstration May 2019	Paul Gross and Dean Baas, from Michigan State University Extension, give a rainfall simulator demonstration. The demonstration covers soil health topics such as runoff, water holding capacity, and aggregate stability.
Capillary Rise	Purdue Soil Health Education website	Video Sep 2017	Dr. John Graveel discusses capillary rise in soil.
Adhesion and Cohesion	Purdue Soil Health Education Website	Video Sep 2017	Dr. John Graveel, Professor of Agronomy at Purdue University discusses adhesion and cohesion within soil.
Soil Moisture	Purdue Soil Health Education Website	Video Sep 2017	Dr. John Graveel, Professor of Agronomy at Purdue University discusses soil moisture in regards to saturation, field capacity, wilting point, plant available water and oven dry weight.
Water Molecule	Purdue Soil Health Education Website	Image Not dated	Diagram of a water molecule.
How to Understand and Interpret Soil Health Tests	Purdue University	Extension Publication Jun 2018	Purdue and CCSI did some research using some commercial soil health tests. This document describes some descriptions and guidelines that came out of doing that work.

Title	Source	Resource type and date	Short Summary
Available Water Capacity	Cornell University	Extension Factsheet Dec 2016	Available Water Capacity (AWC) is an indicator of the range of plant available water the soil can store. The upper end of the range is referred to as ‘field capacity’ or the condition where saturated soil ceases to drain freely from gravity after wetting. The lower end of the range is called the ‘permanent wilting point’, when only water unavailable to plants is left after free drainage.
Water Availability	Soilquality.org – Australia	University Webpage (Australia) Not dated	Of the water entering a soil profile, some will be stored within the rooting zone for plant use, some will evaporate and some will drain away from the plant root zone.
Soil and Water Relationships	Noble Research Institute	Blog post from an independent research institute Sep 2001	Soil texture and structure greatly influence water infiltration, permeability, and water-holding capacity. Soil porosity refers to the space between soil particles, which consists of various amounts of water and air. Porosity depends on both soil texture and structure.

Title

Source

Resource type and date

Short Summary

Available Water Capacity

Cornell University

Extension Factsheet

Dec 2016

Available Water Capacity (AWC) is an indicator of the range of plant available water the soil can store. The upper end of the range is referred to as ‘field capacity’ or the condition where saturated soil ceases to drain freely from gravity after wetting. The lower end of the range is called the ‘permanent wilting point’, when only water unavailable to plants is left after free drainage.

Water Availability

Soilquality.org – Australia

University Webpage (Australia)

Not dated

Of the water entering a soil profile, some will be stored within the rooting zone for plant use, some will evaporate and some will drain away from the plant root zone.

Soil and Water Relationships

Noble Research Institute

Blog post from an independent research institute

Sep 2001

Soil texture and structure greatly influence water infiltration, permeability, and water-holding capacity. Soil porosity refers to the space between soil particles, which consists of various amounts of water and air. Porosity depends on both soil texture and structure.

This page reviewed by Liz Schultheis, Anna Cates, Walt Sell, and Joe Rorick.

Last reviewed 10/1/19