Soil: The Ultimate Defense Against Drought
“When you add organic matter to the soil, no matter the soil texture, whether it’s sand, silt or clay, you increase that soil’s water-holding capacity. Organic matter, which is about 50% carbon, can hold up to 400 times its weight in water. When soils increase their water holding capacity, they are far, far more drought resilient.”
Dale Strickler, Kansas farmer and cover crop expert
Ultimately the answer for making farms more drought-resilient lies in the soil. Globally, groundwater holds more water than rivers and lakes. Healthy soils are water banks that release water slowly to plants and riparian zones. Soil literally “grounds” the physical and kinetic assets of water and harnesses them to hydrate the agricultural system. If soils are abused (by plowing and applying chemicals) they turn delinquent, and their rebellious actions take the form of erosion and flooding. Chemical fertilizers and tillage destroy the beneficial soil microbes and the soil structure that create the conditions for the soil to hold more water. Soils dry out and erode. Heavy equipment compacts soils, preventing water from infiltrating properly. Instead, it runs off into waterways carrying topsoil and toxic agricultural chemicals.
Understanding the Soil Health Quartet of Plants, Microbes, Carbon and Water
Healthy soils harness the power of water by welcoming it to infiltrate to deeper root levels.
Plants are the mediators of life force between Sun and Earth. They have the singular talent of being able to directly capture sunlight energy and transform it into chemical energy — the process is known as photosynthesis and is the basis of life on our planet.
Plants’ vibrating chloroplasts convert the carbon captured from the air into nutrients that power the soil food web and build soil health.
When the soil underground is healthy, it’s a thriving, wild and alive place where things like microbes, bacteria and fungi all work together to provide the ideal environment for water absorption, helping plants to grow.
Soil microbes skillfully engineer their habitats to collectively create conditions in the soil that help retain water. Microbes exude substances that glue soil particles together in formations called “aggregates”. Those aggregates create soil structures with meandering pathways that help slow water passage through the soil. Think about boulders in a creek and how they slow and divert water flow. Healthy soil structure allows water to seep more deeply, making it more available to plant roots.
Aggregates also contain carbon, which acts like a sponge, absorbing water and making the soil more drought-resilient. Keeping soil moist protects microbes from ultraviolet light and allows them to thrive and nourish plants.
Carbon, water, microbes and plants form a “soil health quartet.” Carbon and water are mates—the marriage of the hydrogen molecules in water and the carbon molecules from the atmosphere form carbohydrates that feed the plants and microbiota in the soil, and the soil microbes use carbon as the building block for their habitats.
David Montgomery, author and Professor of Geomorphology at Washington University, explains: “Carbon plays a vital role in the soil in terms of water storage, which is increasingly important as the world is subject to more droughts and extreme weather. There is a direct correlation between organic matter (which is made up of about 50% carbon) and the water-holding capacity of soil. A 1% increase in organic matter increases water-holding capacity by 3%.
Increasing the organic matter content of agricultural soil means more of the rain that falls on a field will seep into the ground and be held there and retained as a reservoir to feed the crops rather than running off into a river or stream and bypassing the agricultural system.”
By following nature’s guidance, regenerative farmers create the conditions for the “soil health quartet” to work its evolutionary magic and capture carbon, store water and build soil fertility.
REGENERATIVE AG PRINCIPLES THAT HELP SOILS RETAIN WATER
Scroll through to explore strategies
Keep Soil Covered Year-Round
Planting cover crops and spreading mulch protects the soil and keeps it cool so it doesn’t bake and dry out. When soil is protected, water infiltrates better rather than running off and causing erosion. Cover crops also send vital nutrients into the soil to build a healthy population of microbial life.
Grow a Diversity of Crops
Growing a variety of crops builds soil health by providing a diverse diet to soil microbes. Various types of microorganisms symbiotically provide different eco-services to those plants. Mycorrhizal fungi, for example, extend the plant root’s reach to harvest water from the soil.
Photo: Singing Frogs Farm
Feed the Soil with Organic Matter
Increasing soil carbon helps rain seep into the ground and retain it there as a reservoir to water crops. Increasing infiltration and eliminating runoff means fewer floods and droughts. More days of moist soil make farmers’ lives easier.
Bring Animals Onto the Land
Animals are a part of almost every natural ecosystem. They’re the ultimate recyclers, converting plant residue into carbon-rich manure. Manure is nature’s perfect organic matter to improve soil health because putting carbon back into the soil is one of the best ways to help it retain water.
Soil, Carbon and Water Connection
Geomorphologist, David Montgomery, discusses the importance of preserving our soils.
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