Soil Quality Under Pressure

Primary Source: Šimanský, V. (2023). Reducing the intensity of machine movement in the field improves the structure of the soil. Acta Fytotechnica et Zootechnica, 16(1), 93–101.

The world’s population is constantly growing, and so it takes a lot of food to support it. As a result, farming has become increasingly industrialized to ensure the maximum yield of food crops. However, this change has not come without its costs. Among other issues, industrial farming uses up quality soil faster than it can be replaced, absorbing nutrients to grow crops at a higher rate than decomposers can re-introduce nutrients to the ecosystem. With these concerns threatening our agricultural future, much research is being done on ways to sustainably increase soil quality. In order to test one of the factors contributing to the speed of quality soil production, a group of researchers in eastern Europe studied the impact of routine traffic from heavy farming machines on soil quality.

An example of healthy, porous soil with notable amounts of decomposing plant-matter. Credit: “Healthy soil, agriculture” from U.S. Department of Agriculture, licensed under CC0 1.0.
A Porous Problem

The key issue being researched in this experiment is soil being regularly compacted as a result of heavy farming equipment passing over it. When soil is compacted, the individual particles that compose the soil are forced closer together, reducing the porosity of the soil. Soil that is porous easily allows for growing plant roots, habitation by various soil organisms, and microbial activities. All of these are important factors which help to chemically alter the soil, gradually turning synthetic material and dead biomass into organic forms that can be utilized by other living organisms, in this case our food crops. With less room for these various organisms to live within the soil, the rate at which new crops use up the organic material within the soil will surpass the ability of the soil, and anything that lives in it, to replenish those organic materials, known generally as humic substances. However, while these processes are generally understood, the degree of compaction produced by heavy farming equipment is not known, nor is the degree to which this compaction would affect the speed at which organic material is returned to the soil. 

Counting Clods

In order to measure how compaction caused by machine traffic impacts the soil, the researchers set up permanent traffic routes on the Slovak University of Agriculture farm in Kolinany, Slovakia. After twelve years following these traffic patterns, soil samples from the trafficked and non-trafficked areas were taken, at depths of 0-10 cm and 10-20 cm. After noting how the samples looked visually, they were run through various chemical tests to determine composition. These tests mainly looked for certain key organic molecules, but also tested more generally for materials that contribute to maintaining soil structure and water retaining ability. Ultimately, the soil samples taken from 0-10 cm at non-trafficked areas of the farm contained a significantly higher percentage of organic carbon molecules, as well as significantly more grams of humic acids (humic substances not soluble below a pH of 2) per kilogram of soil, than that from trafficked areas. Despite this significance seen at shallower depths, this degree of difference between sites was not seen in samples from 10-20 cm, although these samples did have visual signs of more organisms and microbial activity in non-trafficked soil compared to trafficked soil.The difference in significance between depths is most likely due to the limited time of the research period since, while twelve years may seem like a long time, soil maintenance is a slow but constant process. Nonetheless, the significance found here indicates that compaction caused by routine machinery traffic likely prevents the natural ability of the soil to recover organic material, although more in-depth, long-term study is necessary.

An example of compacted soil. It is hardened with only small cracks and crevices for waterflow. There is very little, if any, decaying plant-matter, and many hard rocks/ stones. Source: “Earth section” by 2happy, licensed under CC0 1.0.
Saving Crops from the Ground Up

While the results of this experiment indicate a need for further study, the differences found between the compacted and uncompacted soil still point to a trend of higher quality soil resulting from the limiting of heavy machinery traffic. While other experiments exploring the effects of compaction on soil quality have suggested more direct intervention to physically un-compact affected soil, this study shows that without a change to machinery usage, such intervention would have little effect due to the slow and long-term nature of decomposition processes. Forcibly making soil more porous would be meaningless if heavy machinery traffic would just compact those pores again before communities of organisms can establish in the soil and contribute to decomposition. In short, intervention without preventative measures, such as those taken in this study to limit vehicle traffic to designated paths, would be ineffective and costly. While some ideas on reducing compaction already exist, such as using specially designed drones, the practicality and scientific effects have not been studied in detail, and further studies should explore these options in increased depth.

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Cypress Novick

Cypress Novick

I am a recent graduate of Occidental College in Los Angeles, California, where I studied for my Bachelor's in Biology. My main research interests are wetlands ecology, mycology, estuary ecosystem interactions, and plant-based trophic interactions. I have always been passionate about making science more available and understandable, and am always trying to improve my writing so I may help myself and others be better understood.

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