Is it just me or has anyone else noticed the increased flooding around the globe? Am I the only one who notices the increasing number of droughts? My local area, according to government data, has had seven droughts in the last 11 years. We also had people kayaking in the grocery store parking lot a while back because of a heavy downpour. I believe that agriculture is largely to blame. Why? I personally think that our water cycle is broken. We have broken it.
Water is the most important nutrient. For every 50 pounds of nitrogen that we need to grow a crop, we need approximately 10,000 pounds of water. Why then are we so stuck on managing nitrogen? We are blessed in agriculture with rainfall to help our crops grow, but we are at fault for losing most of it every time it rains. It is the only nutrient that I manage here at Greener Pastures Ranching. On most farms, there is a huge difference between actual rainfall and effective rainfall. Actual rainfall is what ends up in your rain gauge. The effective rainfall is the amount of that rainfall that the plants get to use. If you receive two inches of rain, how much do you think your plants actually get to use? We can’t control the actual rainfall we receive, but we can control the effective rainfall we get to use.
There are three factors that cause the difference between the two.
1. Runoff: Let’s look at a microscopic level at our land when it rains. Without a protective layer on the soil’s surface, one rain drop hurls to the ground and impacts the bare soil. That one rain drop is like a hand grenade, a small explosion that destroys the soil structure. It breaks the soil structure apart, causing soil capping. A capped soil is that smooth surface that eventually cracks when it dries. During the rain storm, this smooth surface causes the second rain drop to runoff, as it cannot penetrate this capped soil. As it runs off the land, it takes the best parts of the damaged aggregates, our valuable organic matter, washing it into our water systems and our rivers. Have you noticed how dirty our rivers look in agricultural areas? But how they are crystal clear in most non-agricultural areas?
2. Evaporation: The moisture that did get into your soil is now vulnerable to evaporation. Rainfall is affected by gravity. The moisture in the soil, however, doesn’t work by gravity. It works by diffusion. This is a movement from an area of greater concentration to an area of lesser concentration, or in other words, wet to dry. If the top layer of the soil’s moisture evaporates, the moisture from further down in the soil profile will move up to the drier area. It will then evaporate and more moisture will move up. Suddenly our water cycle has been reversed. Instead of moisture infiltrating down the soil profile, it is moving up and evaporating from the surface. As this moisture moves up, it can also bring salts. When the water evaporates, these salts are left at the surface, which can be detrimental to plant growth.
3. Infiltration: If we have a very permeable soil, moisture can infiltrate too fast and disappear down through the soil profile. What we need to do as producers is to build soil. We need to use the plants to add organic matter to hold onto the water.
What I have just described is an unhealthy water cycle. It will have capped soil which causes runoff along with excess evaporation from the surface and infiltration that occurs too fast.
Now I’ll describe a healthy water system. Water evaporates from our lakes, ponds and rivers and that moisture forms clouds. These clouds will become dense enough for precipitation to fall back to the ground as rain. We need those rain drops to hit live or dead plant material. We call this our soil armour. Our plants are stronger than the rain drop. This time, the rain drop will break into tiny droplets.
At this point, we also have to hold on to the water. That thatch layer will reduce evaporation. The soil armour protects the soil from sun and the wind. The water will not move up through the soil profile. Instead, moisture can slowly infiltrate down through the soil to replenish water bodies below ground. I know, I just said infiltration was a bad thing, but we need to slow down the infiltration. We do that by building soil. The more exudate we can add to soil through roots, and the more residue we can add to the soil surface, the faster we can build water-holding capacity in our soil. Infiltration is a good thing, if we can slow it down.
So how do we fix this unhealthy cycle? It is really quite simple. We need to leave more residue and build soil through our root growth. We need to make sure that the first rain drop cannot hit exposed soil. We need live or dead plant material to protect soil from runoff and evaporation. We need plenty of organic matter in our soil to hold onto water. We need to build a sponge within our soil to hold water. Any excess moisture that we receive above our water-holding capacity can then infiltrate down into the soil and away to our water bodies, filling them from the bottom. No one else is going to do this for you. There is no magic bullet that will build soil.
After many years of building water-holding capacity on our ranch, we now have the pleasure of watching our water bodies fill up two weeks after a rain from infiltration, instead of filling up during a rainstorm from runoff. When you see this, it is sure gratifying.
It is up to us to manage our water. It frustrates me when I see farmers ditching their fields to drain wet areas. Yes, we get to farm a few more acres, but at what cost? How much flooding occurs downstream? Let’s say every farmer drains three riparian areas in the name of gaining more crop land. Say each riparian area holds an average of 10,000 gallons of water. On a single watershed, we might have 2,500 farmers. That adds 75,000,000 gallons of water to the watershed. How much taxpayer money is spent on flood prevention and repair? How much topsoil is washed away from that land? How many riparian areas are destroyed? I won’t even get into the detrimental ripples caused by the loss of riparian areas. It has a drastic effect on our biodiversity.
I apologize if this article offends you. I believe that we are the cause of many of our own issues. We as humans naturally only look at a small part of the problem and try to bandage it when really we need to take a good look at the whole problem to find permanent solutions. Let’s look closely at cause and effect within our management and start managing our water. It is the most important nutrient that we have in agriculture.