“It's not how much rain you get but how much rain you can keep.”
As I write this in late Oct 2024, we have had no measurable rainfall for the entire month here in west-central Indiana. If you look at the August-through-October total rainfall here, we have not been this dry since 2010, and we've not had a single year in the last 20 years where October has been this dry. We are in a 43-inch annual rainfall area, but what I'm about to share with you will illustrate how broken our water cycle is.
First, let's recognize the importance of a properly functioning water cycle. In order for things to grow we must have water, and it must be able to infiltrate into our soil to where the plants and biology can use it. Then, the living plants transpire moisture back into the air which will later produce more rain. Our water cycle is broken on many of the acres here in central Indiana, and it is not much different elsewhere around the country and world for that matter. What do I mean when I say our water cycle is broken? Simply, we are not cycling the water we have in an effective manner. When we do get rain, it doesn't matter so much how much rain fell but how much rain we absorbed into our soil. If the rain we receive runs off into our lakes and streams, what good is it doing us?
On-farm infiltration observations
I've been on a number of farms locally in the last few weeks performing water infiltration tests, and the data I've collected is very disturbing. Many of our soils cannot infiltrate water effectively. We are seeing a huge difference in farms that are being managed very conventionally with corn-soybean rotations compared to farms being managed regeneratively and using adaptive grazing. In these water infiltration tests we are timing how long it takes for one inch of water to infiltrate into the soil, and often times we'll also measure how long it takes a second inch to infiltrate. On every one of the conventionally managed soybean fields that I have tested, it takes over an hour to infiltrate even 1inch of water. The best results were about three quarters of an inch in one hour.
In these abnormally dry conditions, shouldn't the ground be like a dry sponge waiting to soak up water? Yet, I can go 30-50 yards away into the fence row where the soil has been managed very differently and consistently have found where one inch of water will infiltrate in much less than one minute and often times as quickly as 5-10 seconds. It is not uncommon to see a second inch of water infiltrate in these fence rows in less than one minute. This is a huge contrast in our soils’ ability to infiltrate water in the crop land vs the fence row.
The role of biologically created aggregates
So why the drastic difference between the field and the fence row? It's simple, and it all has to do with soil aggregation or the lack thereof. What is soil aggregation, you ask? A soil aggregate is simply particles of sand, silt, and clay bound together by biological glues. These biological glues that bind the soil particles together are from root exudates of living plants and the microbiology present in that soil. Soil that is well aggregated will resemble chocolate cake in appearance, having many different sized aggregates and pore spaces for water and air to move freely about. Without aggregation, the soil particles become collapsed and plated together forming very tight and compacted soil. This tight, compacted soil cannot infiltrate water or air.
Consequently, when we get a rain, often only a small portion of the precipitation can infiltrate the soil and remain present for the plants and microbiology to use. The rest runs off, carrying valuable topsoil and nutrients with it to pollute our watersheds. It's important to note soils that cannot infiltrate even 1inch of water per hour have little to no aggregation. It's also important to understand that tillage of any kind will not remedy this situation, but we can save that for another conversation. The only way to truly improve water infiltration and utilization is via soil aggregation.
Now, let's look at some of the water infiltration results from regeneratively managed systems that I've tested right along with the conventionally managed soils. On the regeneratively managed soils tested, we had water infiltration for the first 1 inch of water ranging from 21 seconds to just under two minutes. The second inch of water infiltrated in a range from just under one minute to just under 10 minutes. Two inches of water in less than 10 minutes! These soils had from 4-8inch depth of aggregation. The regeneratively managed systems tested have only been under that management for 3-4 years, and prior to that, were conventionally managed with similar water infiltration and depth of aggregation similar to these currently tested conventionally managed systems.
Look at the huge difference in water infiltration from less than two minutes to over one hour for the first inch of water. All of the farms tested are within 10 miles of each other and consist of similar-type heavy clay soils. We have soils that cannot infiltrate one inch of water per hour compared to soils that can infiltrate two inches in less than 10 minutes. Which soils are going to keep more of if not all of the rainfall they receive? Obviously, the ones that can infiltrate more water.
What is the common denominator for better water infiltration? Answer: Depth of soil aggregation. How do we build soil aggregation? Answer: By following the six principles of soil health and applying the three rules of adaptive stewardship to support the four ecosystem processes. By following this 6-3-4ä process, we can build soil aggregation rather quickly and see our water cycle begin to function as it should. Another benefit of building soil aggregation is the mineral cycle will also begin to function as it should resulting in the need for less purchased fertility.
Dig a little, learn a lot
How well is your soil functioning? To find out, take your shovel and dig up a shovel full of your soil to see how it looks. How much aggregation do you see? How much biological activity do you see? How many living roots do you see? What does it smell like? These and other observations will tell you many things about how your soil is functioning.
If you would you like to build resiliency into your soils to weather the extremes of lack of moisture or excess moisture, regenerative agriculture offers us an opportunity to repair, rebuild, revitalize and restore ecosystem function in and on the soils that we are responsible for stewarding.
We at Understanding Ag can help you develop a plan to begin your regenerative journey. Together, we can repair our broken water cycle and restore proper function to our soils. Remember, it’s not how much precipitation you get, it’s how much you can keep—and we can help you keep it.