IRRIGATION IS OVERRATED. HERE’S WHY.
What is the “small water cycle” and why is it (usually) better than irrigation?
A conversation with consultant Jackie Eschelman, an expert in “Holistic Management”
HART HAGAN: The best water is what's already in the soil, because the soil captured it, and is holding onto it. That’s plant-available water.
JACKIE ESHELMAN: Then you have the small water cycle, right? So, when your soil is holding water then those plants transpire. That water turns into dew and drops back into the soil.
There's this really small water cycle that happens. Most people, when they think about the water cycle, they're thinking about what they learned in middle school, where water evaporates off the ocean, turns into clouds and comes over the mountains. Then it rains and washes down the rivers, and back into the ocean.
That's the large water cycle.
But what we really want to see on the land, the thing that is most valuable on the land is that small water cycle. You need water holding capacity in the soil to have an effective small water cycle.
HART HAGAN: You get greater water holding capacity by stopping the irrigation. And your animal impact is just right because of your grazing.
And then your plant communities have more plant families. According to the Jena experiments, the more plant families you have in a given place, the better it is for building soil carbon, which is a proxy for building soil life and soil structure. Soil that has structure is then able to absorb the rain.
JACKIE ESHELMAN: Absolutely.
TAKEAWAYS:
We have overrated and overused irrigation. What matters is not how much water you pour onto the soil surface, but how much water is available to plants.
Too much water can create anaerobic (without oxygen) conditions, which degrades the soil food web and causes compaction, depriving the soil of its natural ability to hold water--like a sponge--and deliver that water to the plants in usable amounts.
We would do well--in our gardening, crop farming and livestock management--to explore ways to let our plants get their water from the rain. It’s not how much rain you get. It’s how much you keep. This is what Allan Savory calls “effective rain.”
Your land keeps the rain when you have good soil. You will have good soil by practicing Gabe Brown’s Principles of Soil Health, which includes avoiding tillage, avoiding chemical fertilizers and toxic pesticides, keeping the soil covered with organic matter and keeping living roots in the ground at all times. Also, nurture biological diversity at all levels, in the soil, in the plant matter and in the animals that interact with the soil.
If we practice the principles of soil health, then the soil will team with living organisms that deliver water and nutrients to the plants. It will also exhibit high infiltration rates, which means most rainfall will soak into the ground and remain available to the plants (and the underground living systems), such that your landscape will be resilient to drought.
Prior to the advent of irrigation, the land was lush and thriving with life, because the plants, animals, fungi and bacteria worked together to condition the soil to teem with life and capture the rainfall. Even most “deserts” were highly functioning ecosystems, featuring tall grasses, unlike the hardscapes of sand and rock that they have become.
We would do well to rethink everything we thought we knew about how to make our gardens, farms and ranches productive and profitable. Mainly, the missing ingredient is our willingness to work with--and mimic--nature.