Understanding the Small Water Cycle

Of all the ecological cycles on our planet, our stewardship impacts the small water cycle more than perhaps any other—for good or for ill. It is critically important to understand how the small water cycle works, why it matters, and how regenerative agriculture practices help it function.

The first thing to understand is that there are two primary water cycles on Earth, the large one and the small one. The large water cycle is the movement of water from the oceans to the land and back to the oceans. The small water cycle is the movement of water that originates on land and moves over land. But you might be surprised to learn that it’s the small water cycle that’s responsible for the majority of the precipitation we can use—up to two-thirds of local rainfall.

That means all living things on land depend on the function of the small water cycle for drinking water, for habitat, for crops, for ecosystem health—water is life. And it’s fair to say that the small water cycle is life, too.

The Connection Between Plants, Transpiration, and Rain

For a well-functioning small water cycle, the more plants that cover the landscape, the better.

That’s because wherever there are plants to transpire water, the more water vapor is present in the air directly above them to form clouds.

How the Small Water Cycle Breaks Down

Conversely, the fewer the plants covering the soil surface, the less water vapor that is generated. Although land with few to no plants can create water vapor through evaporation of water pooled on the soil surface, more of the Sun’s energy is reflected as heat back into the atmosphere. Excess heat drives away clouds.

Keeping living roots in the soil, armor on the ground, increasing biodiversity, integrating livestock, understanding your context, minimizing disturbance—it’s all of the soil health principles working together that impact the small water cycle. Of course, minimizing mechanical or chemical disturbance is foundational: when the soil surface is exposed and/or compacted through frequent tillage, synthetic input usage, fallowing, or overgrazing, rainfall doesn’t infiltrate deeply enough.

Therefore there’s less soil moisture for remaining plants to take up through their roots, less transpiration, less vapor, less rain, the aquifer doesn't recharge, and the cycle breaks down.

How Regenerative Agriculture Facilitates the Small Water Cycle

To facilitate the small water cycle, the ground needs to be covered with a diverse mix of living plants and plant residue with active soil biology and appropriate animal impact to make the best use of every drop of rain it gets. Depending on context, practices that benefit water cycle outcomes include:

• Reducing and/or eliminating tillage and synthetic inputs wherever possible
• Growing a cover crop or cash crop
• Planting a cover crop immediately following grain harvest
• Planting higher-residue crops and leaving residues in the field after harvest
• Delaying termination of cover crops so they become more mature to provide longer-lasting cover on the field before the next crop is planted
• Harvesting more than one cash crop per year, if the growing season allows
• Converting annual cropland to perennial pasture or including a short-term perennial pasture sequence into an annual cropping system
• Grazing plants at a later stage of maturity and at high stock densities to provide more mulch that will last longer

We must all realize the degree to which droughts and floods are often the consequences of improper land management practices that impede the small water cycle. And we must change this dynamic. Water scarcity and water rights issues are extremely relevant today and will only grow more urgent, unless we start solving for protecting and restoring the small water cycle.

While energy resources like oil can potentially be replaced by other things, there is no substitute for water. The Earth provides it through the small water cycle. Or it doesn't, if we do things to break the small water cycle. The good news is that appropriate and continuous application of soil health principles can help regenerate the small water cycle.

In this way, regenerative agriculture doesn't just benefit fields, crops, and farmers, but all living things in the greater ecosystems they belong to.