Water Holding Capacity: Why It Matters for Soil Health and Crop Growth 

Soil is one of planet’s most important resources — it’s responsible for producing 95% of the world’s food and serves as a habitat for over 70% of the world’s species. Among soil’s most interesting talents is its ability to hold water. This allows soil to act as a tank of sorts so that plants can benefit from hydration even between irrigation times and rainfall events. 

The water holding capacity of soil determines how much water is available for crops, impacting their growth, yield, and overall health.  

Growers in regions that experience drought or irregular rainfall are especially impacted by water holding capacity. With limited or unpredictable access to water, the more the soil can help out, the better. 

Many growers who struggle with water holding capacity find that their crops suffer because of it. By improving this capacity, farmers can reduce irrigation frequency, conserve water, and lower labor costs.  

In this post, we will dive into water holding capacity (WHC), how it impacts the environment, how growers can increase their water holding capacity, and its connection to soil health. 

What is water holding capacity and why does it matter?  

Water holding capacity is the ability of soil to hold water despite the force of gravity. There are several factors that influence it, from soil texture to organic matter and soil structure.   

Proper water holding capacity is essential for efficient farming practices and sustainable land management. Growers that have soil with excellent water holding capacity benefit from:  

• Reduced need for irrigation: Higher water holding capacity allows soil to store more water between rainfall or irrigation events, reducing the frequency of irrigation. 

• Healthy crop growth: Soil with high water holding capacity provides a stable water supply. This can minimize the stress plants experience during dry periods and promote steady growth. 

• The prevention of nutrient loss: Water holding capacity reduces nutrient leaching, which means essential nutrients remain in a plant’s root zone. 

How is water holding capacity related to soil health?  

Water holding capacity and healthy soil are closely linked because healthy soils with high organic matter and good structure retain more water and are more resistant to erosion. By improving water holding capacity, farmers can enhance soil health and create resilient farming systems that support long-term productivity.  

What elements of soil impact water holding capacity?  

Every grower aims to have optimal water holding capacity. Four key factors that determine the WHC of soil include organic matter content, soil structure, soil depth, and soil texture.  

Organic Matter Content 

The organic matter inside soil is a huge part of the equation that makes up water holding capacity. Organic matter like compost, manure, or plant residue are ideal for increasing water holding capacity—all those things act like a sponge for healthy soil.  

In fact, according to the Natural Resources Defense Council, every 1% increase in organic matter allows soil to hold an additional 20,000 gallons of water per acre. Whoa! 

Soil Structure 

Well-aggregated soils with good porosity balance water retention and drainage. Compacted or poorly structured soils hinder water infiltration and reduce water holding capacity. 

Soil Depth 

Deeper soils can hold more water, providing a larger reservoir for crops. Shallow soils, on the other hand, have limited water storage capacity. 

Soil Texture 

Soil texture directly correlates with its ability to hold water. The University of California, Division of Agriculture and Natural Resources developed a helpful chart to explore the WHC limits of sandy, loamy, and clay soils.  

The highest water holding capacity of soil is typically found in clay soils, with their small particle sizes and high surface area for water retention. However, these soils need good structure to ensure water is accessible to plants. 

Loamy soils also provide a good balance of WHC and drainage, making them ideal for agriculture. Sandy soils have the lowest water holding capacity, requiring frequent irrigation. 

How do you increase soil water holding capacity? 

If you want to increase the ability of the soil on your land to hold on to water, here are a few tips to help you out: 

• Add Organic Matter (OM): This is the aim of many growers, and for good reason. OM has many benefits, including improving the structure of your soil, which can lead to higher water holding capacity.  

• Reduce Soil Compaction: Compact soil can often mean there isn’t space for water to hold underground. To combat this, growers can avoid working wet soils or soil compaction as strategies to maintain porosity.  

• Plant Cover Crops: Cover crops with deep roots enhance soil aggregation and water retention. 

• Improve Soil Texture: While texture cannot be changed directly, adding organic matter can improve WHC even in sandy soils. 

How does water holding capacity impact the environment?  

Healthy water holding capacity impacts growers in positive ways—from reducing the need for irrigation to helping them produce high quality crops. But the impact on the environment may even be more impressive. Soils with high water holding capacity contribute significantly to a healthy planet: 

• Reducing Flood Risk: By absorbing more water, soils with high water holding capacity reduce surface runoff and help mitigate flooding. 

• Preventing Soil Erosion: Higher water holding capacity improves water infiltration, reducing the likelihood of erosion caused by heavy rainfall. 

• Enhancing Drought Resilience: Soils with higher water holding capacity act as a buffer against droughts, storing water for use during dry periods.  

Want to learn more about soil health?  

Water holding capacity is an essential aspect of soil health and agricultural productivity. By understanding the factors that influence WHC and adopting practices to increase it, farmers can optimize water use, conserve resources, and improve crop yields.  

Growers, if you’re interested in learning more about soil health solutions that can help increase your water holding capacity, see how MyLand can help.