Apr 30, 2025
Determination of Water Holding Capacity (WHC) of Soil Samples
- Thomas Muratore1,
- Melissa Knorr2
- 1Dartmouth College;
- 2University of New Hampshire
- Tumber-Dávila LabTech. support email: grady.welsh@dartmouth.edu
Protocol Citation: Thomas Muratore, Melissa Knorr 2025. Determination of Water Holding Capacity (WHC) of Soil Samples. protocols.io https://dx.doi.org/10.17504/protocols.io.14egnjxbyv5d/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: April 30, 2025
Last Modified: April 30, 2025
Protocol Integer ID: 194127
Abstract
The aim of this protocol is to determine the water holding capacity (WHC) of soil samples. WHC refers to the maximum amount of water a soil can retain against gravitational forces after reaching full saturation. Understanding WHC is critical for laboratory experiments, particularly soil incubations, where maintaining a consistent moisture level is essential for reliable microbial activity measurements. This method is commonly used to determine 60% WHC, a moisture condition considered optimal for sustaining microbial processes during incubation studies.
Materials
Drying oven set to 30°C, Funnels (one per sample), Whatman No. 40 filter papers (one per sample), Graduated cylinders (one per sample), Beakers (one per sample), Parafilm, Deionized (DI) water, Balance (for weighing soil), Spatula or scoop for handling soil, Timer or clock, Laboratory notebook or data sheet for recording measurements
Sample Preparation
Sample Preparation
Dry soil samples overnight at 30°C.
Sub-sample dried soils to obtain a representative portion of each sample.
Weighing
Weighing
Weigh out 25 g of dried soil for each sample using a balance.
Filtration Setup
Filtration Setup
Line each funnel with a Whatman No. 40 filter paper.
Place each funnel into a graduated cylinder.
Initial Wetting
Initial Wetting
Slowly add 50 mL of DI water evenly across the surface of the soil sample in the funnel.
Allow the sample to stand for several hours so that water can percolate through.
Re-wetting
Re-wetting
Carefully collect the water that percolated through the soil into a beaker.
Reapply this percolated water back onto the soil surface, again dripping evenly.
Sealing
Sealing
Cover the top of the funnel and sample with parafilm.
Poke a small hole in the center of the parafilm to allow slow drainage.
Overnight Drainage
Overnight Drainage
Leave the setup to drain overnight at room temperature.
Measurement
Measurement
The next morning, measure and record the volume (mL) of water that has percolated through into the graduated cylinder.
Calculation
Calculation
Calculate the water holding capacity (WHC) using the volume of water retained by the soil (based on the initial 50 mL added minus the volume collected).
WHC (%) = (Volume of water retained by soil (v1-v2) / weight of soil) * 100%
Note: Can determine 60% WHC for an incubation moisture manipulation set-up by *0.6
| A | B | C | D | E | F | |
| Sample | Wt of soil sample (g) | Vol of water added (ml)– V1 | Vol of water collected (ml) – V2 | V1-V2 (ml) | WHC % | |
| BW-1-m | 25.02 | 50 | 30 | 20 | 79.9 |