Soil and Plants Need Each Other

streamline and turbulent wind around different windbreaks

It is common knowledge that plants need soil. However, not often enough is it asked; does soil actually need plants? The relationship between plants and soil is more mutually beneficial than most would think. Soil is the uppermost layer of the earth in which plants grow. It is a composite of rock particles, organic materials and microorganisms. Within the soil there is an entire complex ecosystem of microorganisms, insects, and burrowing critters—their activity is as vital to soil composition as are the nonliving (abiotic) components of soil. 


Floods spread water over a floodplain once soil becomes too saturated to hold additional water. Flood water moves across the earth and erodes soil as it washes over a landscape. Wind, which is also a fluid force of nature, can contribute to soil erosion as well. This is especially the case in certain narrowed areas of the landscape where wind funnels through a “corridor” – this increases wind velocity by reducing air pressure, a phenomenon explained by the Venturi effect. Some erosion is simply a natural process, but as with many things in nature, there must be a balance. Too much

Turbulent eddys form around obstacles

erosion leads to arid soils deprived of organic materials and incapable of supporting life. A cover-crop grown over an underutilized agriculture field can significantly preserve the soil's quality in the area and protect it from abrasive forces. Windbreaks which perpendicularly intercept prevailing winds in an open space also help protect soil, by decreasing wind velocity. These windbreaks can be trees, or even shrubby herbaceous plantings. Windbreaks created by trees in a field can be a critical way for increasing soil health by protecting surface soil from powerful windflows across a wide-open space. Adding vegetation can also protect soil from erosion caused by floods by giving the soil something to “grab” onto as floodwaters sweep an area. Some types of trees can also help decrease a local water table by taking-up water; consider that just one large tree can lift up an average of 100 gallons of water out of the ground.

We are seeing the effects of desertification driven by drought and decreased vegetation coverage in many areas of the world. Adding trees to a space is just one way to increase soil health and combat this ecological threat (a few arboreal-lacking biomes are exceptions). Without vegetation, soil “dies” and without soil, the vegetation dies--once their relationship is disrupted it creates a dangerous negative feedback loop. The maintenance of healthy soil is essential to supporting a functional ecosystem and is also extraordinarily important for food security, as well as preventing species extinction of plants and the animals that rely on those plants. These and other considerations should lead to the realization that soil health is vital for our own survival and we should approach landscape design and land-use planning with that in mind.


By Molly Burhans

catholicgeo.org

Sources:
[photo quote] Pope Francis I. “Laudato Si’ - Encyclical Letter, On Care for Our Common Home, Pope Franci I.” Vatican: the Holy See. Vatican Website. Libreria Editrice Vaticana, 2015. Web. July. 2015.

This whole post is influenced by the work of Richard T. T. Forman.

A nutrient rich upper-layer of of soil, or organic layer, mingles with mineral rich parent material from the lowest layer of soil. In this image it combines and coalesces overtime to form this fascinating stagnogley soil. Stagnogley soils are loamy or clayey soil with a relatively impervious subsurface horizon. The colors can indicate the aerobic conditions of soil with some iron content--this soil was likely very moist/waterlogged for extended amounts of time.