Is it possible to quantify the improvement in soil’s water retention capacity with regenerative farming practices?
The soil’s water holding (or retention) capacity is the amount of water that a given soil can hold for crop use. Why is it so important? When there is a deficit in the amount of water in the soil, the soil needs to be replenished by precipitation or irrigation.
The key is for farmers to understand the nuances of soil water holding capacity and how to manage it so that the land does not require very much irrigation or suffer from a drought. The higher the water holding capacity, the more resilient the crop is because the soil is able to resist extreme weather events.
As extreme weather patterns increase (very long and wet winters, very dry and hot summers), water retention is the variable that provides the most improvement to the resilience of soil. By improving soil quality and restoring soil’s water retention capacity, farmers will quickly experience the benefits on crop resilience.
What Improves Water Holding Capacity?
Apart from its texture (the proportion of sand, silt, and clay), Soil Organic Matter (SOM) plays a major role in determining a soil’s Water Holding Capacity. SOM acts like a sponge; it improves soil structure, allowing it to hold significantly more water in its pore spaces, and, in times of heavy rainfall, reduces surface runoff and erosion.
Regenerative agriculture practices increase SOM primarily through three mechanisms:
- Cover Cropping and Continuous Root Presence: Keeping living roots in the ground year-round (through practices like cover cropping) provides a constant source of organic material to the soil.
- Minimizing Disturbance (No-Till/Reduced Tillage): Tillage rapidly oxidizes and destroys existing SOM, releasing its stored carbon (and water-holding capacity) into the atmosphere. By utilizing no-till or reduced tillage practices, SOM is preserved and allowed to accumulate near the surface.
- Increased Biological Activity: Practices like applying compost and biofertilizers (which feed the microbial life) stimulate soil fungi and bacteria. These organisms are the biological engine that creates stable humus and SOM, which directly improves the soil’s spongy structure.
The Soil Heroes Water Holding Capacity Project
This project worked with the University of Wageningen to test the evolving water holding capacity across 35ha. The goal was to compare the water holding capacity of plots in various phases of transition to regenerative agriculture with fields that were still under conventional practices.
We found that the topsoil (5-20 cm) under regenerative management had a higher water holding capacity compared to conventional methods after 1-5 years into the regenerative transition.
You can read the reports on the field data HERE and the full summary report HERE
