Heavy farm machinery can compress the soil, affecting plant growth and environmental conditions. However, it is important to know the difference between soil compaction in the lower soil layers and the upper 20 cm or more, which for plowed soil corresponds to the plow layer, called also topsoil.
Compaction of the lower soil layer causes long-term damage, which is very important to avoid. In the case of topsoil, compaction can be corrected by tillage, changes in temperature from cold to thaw or rain and drought, and microbial activity in the soil.
“Nevertheless, it is generally known that the structure of the upper layer of the soil greatly affects the yield of the plant. Here we see a large pile of decaying organic matter and a living biological activity . A very large part of the root mass of plants is found. in the upper soil. This means that the poor conditions for the necessary oxygen chemical and biological processes can impair the use of nutrients. of the plant and lead to emissions of nitrous oxide and other gases. Therefore, it is very important that we examine the process of compaction of the topsoil,” said senior researcher and emeritus Per Schjønning from the Department of Agroecology at Aarhus University.
In a recent scientific article entitled “An empirical model for predicting the change in surface traffic in the field” and published in Soil and Cultivation Studieshe presented a new model that can predict topsoil deformation caused by agricultural machinery.
For the lower layers of the soil, there is a certain amount of pressure that must not be exceeded to avoid damage to the soil. It is assumed that the soil is elastic up to this pressure value. The topsoil, on the other hand, consists of a mixture of large and small crumbs and clods that are gradually degraded. Therefore, another method is needed. Newly plowed soil can be too loose. This is one of the reasons why furrow packers and rollers are used. On the other hand, the soil should not be compacted too much. Therefore, a tool is needed to predict how much a traffic will compact the soil.
The research is based on extensive field studies in which Schjønning and his colleagues measured and analyzed the mechanical forces under the tires and the physical changes that occur on the surface as a result of farm traffic for many years. Based on the collected data and advanced statistical methods, he developed an empirical model that can estimate the deformation of the topsoil.
“The model takes into account various soil properties – organic matter content, pre-traffic density, clay and water content. Similarly, knowledge of tire load, tire type, and recommended and applied tire pressure is used. The model can provide an estimate of the expected deformation of the surface soil. This will be extremely valuable knowledge for agricultural advisors and not least for the farmer himself,” explains Schjønning.
The new model has the potential to improve the planning and management of agricultural activities. If the farmer has an accurate prediction of what will happen to the density of the topsoil when he chooses to drive a particular machine in a field at a given time, he can more easily optimize the conditions for in plant growth.
“This makes it easier for the farmer to choose the tire fitment, weight and tire pressure of the machines, as well as the best time (moisture content) for a particular field operation, ” he said.
The application of the practice model
The model is based mainly on Danish soil, which is quite sandy. If the model is to be widely used at the international level, it will require testing on more clay soils and possibly adjusting it based on additional measurements. Additionally, the shear forces that occur under the traction wheels can cause bends to result.
“Our research group at Aarhus University has already developed a decision support system that makes it possible to simulate the traffic situation for subsoil protection. It may be possible to incorporate the new model into this system and thus provide a more realistic and relevant advice on the surface,” explains Per Schjønning.
More information:
Per Schjønning, An empirical model for predicting topsoil deformation in farm traffic, Soil and Cultivation Studies (2022). DOI: 10.1016/j.still.2022.105589
Provided by Aarhus University
Citation: Predicting how topsoil is affected by field traffic (2023, July 3) retrieved 4 July 2023 from https://phys.org/news/2023-07-topsoil-affected-field-traffic. html
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