By: Emily Rossiter
Did you know that that United States loses 11 tons of topsoil per acre each year? However, the United States Department of Agriculture T-Factor states that an acceptable rate is only 4-5 tons (Hoorman, 2023). This is a pressing matter, because topsoil contains the most organic matter, meaning that it provides nutrients for plants to grow. Without topsoil, we wouldn’t be able to grow food to survive. This means that topsoil is arguably our most precious natural resource, alongside water. The USDA is urging farmers to switch up their farming practices, because they are predicting that Iowa could lose enough topsoil within the next 60 years that our current agriculture practices would no longer be sustainable (Fong, 2023). It is estimated that the US is losing topsoil 10x faster than nature can replenish it, because it takes hundreds of years for just 1 inch of topsoil to be replenished (Powers, 2022).
Here at Whiterock, we practice sustainable agriculture methods to mitigate the loss of topsoil. We do this in a couple of different ways, which we will discuss in a bit. As many of you know, Whiterock sits on 5500 acres of land. Of those 5500 acres, nearly 1400 acres are used for our sustainable agriculture practices. 550 acres is used for row crops and of that 550, we custom farm 250 acres, where we rotate small grains. We then lease out the other 300 acres for row crops. The rest of the acres are used as pastureland (which we will discuss towards the end of this post).
The first sustainable agriculture method we’ll talk about is the use of cover crops. Cover crops are an in-field practice that entails planting another form of vegetation to cover the soil during the time between harvest and planting the next year's cash crop. We use cover crops to build, protect and armor the soil by having continuous living roots in the ground to help hold down the soil. The plants also act as a barrier between rainfall and the bare soil. A heavy rainfall will breakdown a soil particle, causing the soil to erode, so the plants will help soften the blow. The use of small grains helps diversify crop rotation and adding these small grains will help with soil health and can help combat diseases in the soil. This idea isn’t fully understood by scientists quite yet, but they are noticing a correlation between cover crops and soil-borne diseases being suppressed. This may be because the use of cover crops increases the overall activity and diversity of soil microbiota (microorganisms that live in the soil). An increase in microbial diversity and activity not only increases the competition with plant pathogens for nutrients, but also may release more compounds in the soil that interfere with the pathogen’s ability to grow and develop. Also, there are certain species of cover crops that are known to release fungitoxic compounds (hinders the growth of fungus). The small grains that we plant here at Whiterock include production rye and oats. Our goal for 2024 is to have nearly 20 acres of oats and 16 acres of production rye. After we harvest the rye, we process the seed and then plant a rye cover crop that fall, immediately following harvest, whereas we like to sell the oats locally. Rye is a hearty type of plant that grows during the cold season.
Another technique that we practice and is recommended by the USDA NRCS, is no-till farming methods. The no-till farming technique is a way of planting crops without disturbing the soil through tillage. We do this because the soil is alive! There is a whole biological community in soil that is negatively impacted by tilling. Studies show that practicing no-till farming methods helps increase the organic matter in several inches of topsoil. Not to mention that practicing no-till farming methods also helps to decrease the erosion of topsoil. Keeping the soil intact helps to maintain root channels that help facilitate greater water infiltration and storage. However, if you’re going to practice no-till farming methods, it is also recommended that you consider cover crops as well. It has been shown that the use of cover crops will ensure the long-term viability of no-till farming methods.
We also don’t use any fungicide or pesticide on our crops, but we will occasionally use herbicide and commercial fertilizers. We are continuously experimenting and looking for different ways to reduce inputs and improve soil health. In our pasture systems, clover is great at replenishing nitrogen in the soil, so we try our best to manage our pastures and promote a sustaining forage that is both good for the animals and the land.
Another method we use to help combat soil erosion is by enrolling acres in CRP (Conservation Reserve Program). This land is not as productive for row crops for multiple different reasons, like it could be on a steep hillside, or maybe the soil is too sandy. Once it’s converted to CRP land, it is usually a mix of native plants that is booming with biodiversity, which wildlife tends to love.
We also use terraces and waterways across our crop land to help prevent soil erosion. A terrace is an earth embankment or a channel that runs across the slope of a hill to intercept water runoff by catching it and letting it soak into the ground and then deliver it to a safe outlet, rather than letting the water rush down the slope and taking precious topsoil with it. This also helps conserve moisture in the soil along steep slopes. Some terraces are also seeded with grass for extra erosion control and to provide a nesting habitat for birds. When it comes to waterways, they help carry the surface water runoff out of a field. They also help mitigate gully erosion and improve water quality by lowering the sediment loads in runoff.
Another way Whiterock is protecting Iowa soil is through our soil health easements. A conservation easement is a voluntary, permanent legal agreement between a landowner and a conservation group that protects the land for future generations. A soil health easement is different than your usual conservation easements because it primarily focuses on soil health. Through our soil health easement, we work with private landowners (primarily farmers) to ensure that they are practicing the sustainable agriculture techniques that are outlined in the easement.
The last main sustainable agriculture technique that we use is rotational grazing. Grazing helps soil health by reducing soil compaction and it increases soil carbon. We have around 800 acres of pastureland that is rotationally grazed. Cows are grazed through paddock systems every several days, depending on the size of the paddock and the size of the cow herd, to prevent overgrazing. We practice this method because the land can only handle so much, so by limiting the herd to a small area of land for a limited amount of time, we are ensuring that the land isn’t being overused. Occasionally, we will practice flash grazing, which is a large sum of animals on a small area of land for a very short amount of time. This is supposed to mimic how ancestral herds would flash graze an area. Besides our bison herd, we do not have any of our own livestock. So, any cows or goats that you see on our land are owned by a local rancher that is leasing out our land.
Sources [for stats]:
Powers, M. (2022, May 22). Soil, science, and society: We’re running out of dirt. FEW Resources.org. https://www.fewresources.org/soil-science-and-society-were-running-out-of-dirt.html#:~:text=The%20United%20States%20is%20losing,arable%20land%20has%20become%20unproductive.
Fong, A. J. (2023, January 3). Iowa’s prized topsoil could have 60 years left, experts say. wqad.com. https://www.wqad.com/article/news/local/iowa-topsoil-erosion/526-a12810c0-a82f-48d6-bd76-dd45f8acf3d6
Hoorman, J. (2023, January 5). U.S.A. soil erosion - ohio AG NET: Ohio’s Country Journal. Ohio Ag Net | Ohio’s Country Journal. https://ocj.com/2023/01/usa-soil-erosion/#:~:text=On%20average%2C%20farmed%20fields%20were,11%20tons%2Facre%2Fyear.