Soil Compaction Guide: How to Reduce Soil Compaction

Soil compaction occurs when soil particles are compressed together too tightly, reducing pore space between soil particles and preventing air and water from flowing at their optimum. Soil compaction impedes proper nutrient uptake and root growth, which can lead to the starvation of your crops. A number of factors can lead to soil compaction, including the use of heavy machinery, excessive soil moisture, foot traffic, and climate change.

There are two main types of soil compaction. Topsoil compaction involves contact pressure that compresses the top level of your soil surface. Subsoil compaction is typically a result of heavy machinery with high axle loads that compress the topsoil so severely that the untenable conditions radiate to the deeper soil levels. Even a small amount of subsoil compaction can reduce crop yields for years.

There are a few different factors that can affect the extremity of soil compaction, including the following causes.

1. 1. Soil profile: Dry soils have a relatively high load-bearing capacity. In general, clay or wet soils have fewer voids and become compacted more easily than dry soils. Some soils, such as sandy or loamy soils, are naturally prone to denser soil volume and more compaction than other soil types. These soils are likely to experience compaction more often with the absence of proper farming methods or drainage practices.
2. 2. Poor drainage: Overwatered, wet soils with poor aeration and low porosity are more likely to become severely compacted. When water is able to properly penetrate the soil, your plant roots to absorb nutrients more effectively. Standing water (from raindrops or overwatering) that sits on compacted topsoil can lead to the soil’s moisture content becoming too high. This can create maladaptive soil conditions and potentially starve your crops.
3. 3. Thatch buildup: Thatch is an accumulation of living and dead stems, roots, and rhizomes that build up around your grass. Accumulating thatch material on your lawn is not the same as mulching your soil with organic matter; in fact, it can increase the level of topsoil compaction. Thatch buildup can suffocate your lawn, reducing the amount of air and water that can penetrate your soil.
4. 4. Foot traffic: Heavy foot traffic from humans and grazing livestock can lead to compacted topsoil. This reduces soil permeability and increases the density of the soil, eventually leading to nutrient and air penetration resistance that can inhibit crop production and plant growth.
5. 5. Field operations: Wheel traffic from over-plowing and deep tillage operations can reduce soil strength and increase the degree of compaction. Tire pressure from heavy equipment runs across the ground and applies pressure to further compact the soil. (You might notice that crops rarely grow in places with heavy wheel tracks.) Repeated soil tillage operations, plowing, and ground treatments also destroy aggregates that bind the soil particles together. This can offset the proper balance of the soil structure, leading to severe subsoil compaction.
6. 6. Climate change: Global warming and climate change can also contribute to soil compaction. As soil temperatures and/or availability of nutrients fluctuates, the soil becomes imbalanced, leading to clumping, soil erosion, leaching, or other irregularities that enable more compacting.

Soil compaction can lead to environmental harm as well as poor growing conditions. Here are some of the common effects of soil compaction.

1. 1. Poor aeration: Soil compaction increases with a lack of proper aeration, and it can also cause a lack of proper aeration in turn. Watering any soil that isn’t aerating properly can increase soil density, causing soil particles to bind together and starve your plant’s root system.
2. 2. Pests and diseases: Compacted soil is an excellent breeding ground for pests and diseases. Waterlogged, compacted soil lacks the proper nutrients necessary to suppress certain bacteria and organisms in the soil, which can contribute to root rot and sick plants.
3. 3. Poor crop yield: Plants in compacted soil may see consistently poor crop growth and yields season after season because the lack of space between soil particles can limit the space for root development. Poor root growth also inhibits a plant’s ability to absorb nutrients, which can lead to poorly producing crops.
4. 4. Flooding: Areas with severely compacted soils are more prone to runoff or flooding, as the excess water content can’t properly penetrate the soil. This can lead to both structural and further agricultural damage through soil erosion.

There are a few things that you can do to reduce soil compaction in your crops. While topsoil is generally easier to loosen, subsoil compaction is significantly more difficult to address. Take preventative measures to avoid the risk of deeply compacted soil. See below for some tips on how to help reduce soil compaction in your lawn or garden:

1. 1. Use perlite or vermiculite. Adding perlite and vermiculite to the compacted layer of your soil can promote granular soil aeration and water infiltration. Perlite often appears in cactus soil mixes and soil mixes for other drought-tolerant plants. Vermiculite flakes are mined and heated at high temperatures to form a worm-like shape to create space between soil particles and retain moisture.
2. 2. Use no-till soils. No-till soils are crafted with higher biological activity than repeatedly used/treated soils, which can naturally help prevent your soil from becoming compacted. No-till soils have a higher level of soil aggregates and are associated with less erosion and less runoff, which can protect the sublayers from heavy compaction.
3. 3. Avoid working with wet soils. Dry soils can withstand the weight of machinery much better than wet soils. In addition, machinery with wider wheels and better weight distribution may not compact the soil as severely.
4. 4. Check your soil regularly. Use a penetrometer to check the moisture and resistance levels of the soil periodically. Knowing how compacted your soil already is can help dictate which methods you use to treat your ground soil.
5. 5. Add soil organic matter. Adding organic matter to your soil can help reduce its bulk density and provide it with beneficial microbial activity. Spreading out manure or compost on your soil can also provide it with additional nutrients and create space between the soil particles. Adding earthworms to your soil can also help create some distance between your soil particles.

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