(The following is from my monthly newsletter. This series began in March 2022 and has continued for nearly a full year, with its final installment in February 2023. Below is the “better” edited version from what I originally emailed to my followers.)

Water. Water is essential for all life. Without it, we and everything around us wouldn’t exist.

Here on Earth, water is perpetually cycled. It’s hard to pinpoint where it begins because every part of the cycle is considered a starting point. Regardless, we all know that the water cycle is in the form of clouds, rain, water bodies, condensation, evaporation… and so on. A nice simple view.

But it’s over-simplistic. To me, such a view mostly (not always) forgets about plants. Plants play a very important role in the water cycle! Almost 95% of a plant is made up of water. Plants will “let go” of some water via transpiration. Water vapour from plants (combined with water vapour from evaporation) helps to form clouds, which condense into rain, which fills lakes and rivers, which gives off (evaporates) water, and so on.

Again, still a simplistic view. But, do we want to venture down that rabbit hole in this article? No, neither do I. Without a doubt, there’s still a lot more to the water cycle that is easily discoverable on any search engine, especially if you want to dig into comparing how the water cycle works in deserts versus tropical rainforests. But, for today, our primary focus is how management practices using planning and livestock make the water cycle more (or less) effective.

First, we need to see what happens to the water after it rains. Then, we need to see where it goes and what happens to it on a landscape full of vegetation versus bare soil. Finally, we look at what it takes to make your resource base (the land) have an effective water cycle versus a non-effective water cycle.

My biggest TL;DR (too long; didn’t read) hint is that it’s all about the plants. Plants are what really help make the water cycle effective, both in life and in death.

What Happens When it Rains?

We’re almost always grateful when it rains (except when there’s too much), but have you thought of what happens to that water after it hits the landscape?

Three outcomes happen to this locally finite resource:

1. Evaporation
2. Runoff
3. Retention

As you read through this newsletter, ask yourself this question: Which of these is considered “effective” in terms of capturing and storing for future tough times ahead?

How do plants get water?

Water is an essential nutrient for plants as much as for animals. Plants need water in order for them to draw dissolved nutrients up into their leaves and stem. Water is also needed for their cells to be as rigid as possible, which gives plants the ability to hold up their leaves, stems, and flowers toward the sun. Water also gives roots the same structural ability to grow deep into the soil. Water helps roots store energy for tough times ahead.

Roots are how plants can collect water. Mycorrhizal fungi also help a plant get more water. Roots obtain most water from soil aggregates. Obviously, when it rains, plants will take advantage of this very limited yet readily-available water source as well.

Soil aggregates act like a sponge. They hang on to water and absorb it very quickly when it rains. Aggregates that are saturated with water are easy for root hairs to access water from. Root hairs will also grab any water particles that haven’t yet been absorbed by soil particles that are still trickling down into the soil profile: this is more evident in sandy soils than clay soils.

When soil aggregates are dry, they cling on to water molecules they absorb, and refuse to let go. This makes it very difficult for root hairs to try to force much if any, water from these stubborn particles.

Think of it as you versus a sponge. You’re the root hairs, and the soil aggregate is the sponge. Wet it as much as you like, and the sponge will only hold so much water before it’s dripping all over your hand. Want more water from it? Wring it out as much as you can. Root hairs, realistically, only take what they need. So, if you now have a still-wet sponge but no more water can be wrung out no matter how hard you try, you won’t get any more water from it. Nor will those root hairs.

What if the sponge is already bone-dry? Add just one single drop of water to it, then try to squeeze that water out. You should get nothing except a slightly wetter sponge. Try adding a couple more drops and squeeze it again. Again, you will get nothing.

This is just like with very dry soil aggregates. They will cling on to what little water there is and there’s nothing the poor root hairs can do about it. Until it rains some more, of course!

As a result, plants suffer. Their growth rate slows, and they wilt, becoming water stressed. Their ability to uptake nutrients is severely limited.

How Can You Minimize Dry Soil??

There are four ways, all of which I will discuss more on soon (or in a future newsletter):

1. Increase plant diversity.
2. Minimize the presence of bare soil.
3. Minimize surface disturbance.
4. More plant residue (soil armour).

I won’t add a fifth one to the list, as it’s more luck and studying weather patterns than anything. But, if you must ask, it’s “pray for rain.”

Now, let’s look at what happens to water once it does rain, and that water is bound and determined to seep down into the soil.

Water in the Soil Profile: How Deep, How Fast?

The rain has finally come. Water is ready to go down, wherever that may be. The gravitational pull towards the centre of the earth is ever present, yet there’s just a small problem.

Some of the water is being held back. Not all of it is going to go down into the soil at the same rate. Why??

The answer is, not all soil is made equal. Water must go down, but the rate as to how deep and how fast it goes depends on three important factors, none of which are mutually exclusive from each other:

1. Rate of application: How much snowmelt or rain fell on the landscape (or, also applicable, how much-irrigated water was applied). A little bit of water won’t go down as deep or as quickly as a lot, depending on the other two factors.
2. Soil surface porosity: Whether the soil surface is capped (more on this soon), or covered in dead and living plant material. Capped soil stops water from going down; soils covered in vegetative armour enable water to quickly move down to the below-ground layers.
3. Soil texture: The question is if the soil is made up of one or all combinations of sand, silt, loam, or clay. This determines the porosity of the soil. Clay is much less porous than sand. (Keep in mind: Silt and loam are situated in the middle.) Water, therefore, will travel more quickly down through sandy soil than clayey (or “gumbo”) soil; plants are able to capture moisture more readily in sand soil as opposed to clay. Also, clay soils capture and hold moisture more readily than sandy soils. This is because clay soils have a much greater surface area than sandy soils. The greater the surface area, the slower water will travel.

As we all know, we cannot change the type of soil we have on our land. We can make the very costly decision of pulling up roots (pun not intended) and moving to an entirely different area with better soil, but that is neither here nor there, nor much of an option. What soil[s] we get is what we must work with.

This leaves us with determining how to be “effective” in terms of capturing water. And, in order to answer that question, earlier I asked which of the three outcomes was most effective in capturing rainfall.

The answer is:

Retention.

In Order to Have an Effective Water Cycle…

We must utilize vegetation in order to slow the flow of water into the soil profile. Not stop it entirely, but slow it enough that it is merely a gentle trickle. Like, taking a nice gentle shower instead of using the pressure washer meant for the tractor on yourself. Right?

Also, we need to capture water for later. The soil needs to become like a water-holding tank instead of a drainage canal. What if it doesn’t rain for the next three months? Will your soil have enough water stored up for plants to take what they need during those dry months?

A good way to remember that is by this little quip: slow the flow, retain the H₂O!

Soil armour is crucial for ALL of this. Soil armour is only provided by the kind of management practices that allow for it to happen. In terms of grazing, this means employing more than just the “take half, leave half” rule of thumb (it’s more of a loose guideline). It means planning out pasture moves so that you’re always going to be leaving plenty of residues behind.

As Jim Gerrish has always noted in his grazing classes, “Don’t be afraid to waste grass!” How true.

If you can scrape up enough residue in a small area to fill the palm of your hand, that’s a good indicator that you have a healthy amount of soil armour.

In a future newsletter, I will expand more on the “take half, leave half” rule and discuss its faults. I’ll very briefly mention one here: if there isn’t much forage on the pasture, to begin with, why would a producer take half of it when the other half won’t be sufficient to protect the soil? It’s an entirely different story if you have plenty of forage available.

Leaving residue (or litter) behind feeds the soil biology. Soil biology turns that into soil organic matter, which becomes a sponge for water collection. Animals consume the vegetation and return it back to the land as manure, also contributing to building soil organic matter and feeding the soil microbes.

It’s a beautiful cycle. That’s nutrient cycling, something which I will discuss in July’s newsletter!

How does an effective water cycle compare to a non-effective water cycle, though?

What’s a “non-effective water cycle?”

The above photo is a great start to show how the non-effective water cycle works.

When a raindrop lands on the soil (the force of gravity driving it toward the Earth’s core), it doesn’t land gently. It lands with such force that it sends soil particles flying through the air. That’s just one water drop. Think of trillions more hitting the soil surface! All those seemingly innocent drops of water falling from the sky constantly bombard the soil surface, displacing soil particles and disrupting soil structure.

When the bare soil surface becomes wet with water, another thing starts to happen: capping. Capping is closely associated with runoff and consequently erosion.

Capping of the soil occurs when the driving force of the raindrop breaks the crumb structure and frees fine soil particles. Fine particles are lost to the air or are carried away by the water. Never to return.

Runoff washes away these fine particles into ditches, lower areas of the field or pasture, and/or into water bodies to be lost forever. Heavier particles, on the other hand, settle down and seal (or “cap”) the soil surface.

Capped soil prevents water from penetrating into the soil profile. This is a big issue for plants. Plants have little choice but to keep their roots at or near the soil surface so they can get the moisture they need. Capping does more damage though; it prevents oxygen from getting in and carbon dioxide from getting out. Essentially, this suffocates soil biology to death.

Should more rain fall on the kind of surface pictured above, it will have nowhere else to go but downhill. Or, a large portion will be evaporated. Very, very little retention occurs on such a desertified landscape.

The Pasture Context

I realize that the above demonstration may be seen as a bit extreme for most pastures. However, lack of residue from overgrazing (or just bad planning) still leaves it tending towards a non-effective water cycle. Capping will occur, even though it’s not altogether noticeable. Also, those short little plants don’t do a good job of slowing those raindrops coming down at a terminal velocity of 9.8 meters per second. Soil particles are still going to be displaced, and plenty of that precious rainwater runs off or evaporates. Not much will be retained in the soil profile. If it does, it’ll get quickly used up by the plants.

It’s like trying to fill a barrel that has a hole near the bottom. You can fill it with as much water as you think that entire barrel will hold, but if you haven’t fixed the hole, that barrel will only hold as much water as that hole will allow.

Soon, in the absence of rainfall and at least a few days of hot weather, the pasture will show how much it’s suffering from lack of water; plants wilt and start to turn brown. Should the hot spell continue, those plants will die.

So, instead of adding more water or wishing for more rain, find that hole (your soil armour or lack thereof) and fix it so that your soil (the barrel) retains as much water as it possibly can.

Rain is great because it makes everyone look good. But not droughts. Droughts are where bad management reveals its ugly head. A lesson to be made is that you should start planning for a drought during the good wet years, not when there’s a drought already happening. Planning for a drought in a drought is planning for a carriage ride when the horse has long escaped the stable and joined the local wildies.

Conclusions

The water cycle shows the importance of needing plants, lots and lots of plants. But as I will discuss in the next post, plants are great for more than just retaining water. These highly cheap, all-natural green photosynthetic solar panels are great at harnessing the awesome power of the sun…