Soil compaction can be minimized but cannot be eliminated. What is soil compaction, and how does it occur?
When soil particles are pushed together so the amount of air space between the soil particles is reduced as compared to normal, it’s called soil compaction. Larger equipment, earlier planting when the soil may not be ready, use of loaded trucks on the soil and manure tankers crossing the field can lead to compacted soils. Working wet soils when the content of soil moisture is above field capacity and soil strength is reduced adds to soil compaction.
Soil compaction reduces yields. You know that soil compaction should be avoided when possible. But what can you do with wet springs? Crops must be planted before it is too late, even at the risk of causing some compaction.
We know that soil compaction causes yield reduction because roots cannot penetrate the compacted layers and their growth is stunted. Plants cannot use the nutrients and water below the compacted layers. Water absorption from rain is reduced, which increases the chances for soil erosion.
Soil compaction in dry years produces stunted plants and reduced yields due to reduced root growth. However, soil compaction in wet years reduces soil aeration, and increases denitrification and loss of nitrogen into the atmosphere. It can also decrease potassium uptake, increase disease pressure, and produce weaker roots and stalks.
Minimizing soil compaction
What can we do to reduce soil compaction? Here are some practices I have watched farmers adopt to attempt to reduce the potential for soil compaction, and to lessen possible impacts if it occurs:
Prepare ground properly and plant with common sense. It is common sense to avoid fieldwork when soils are wet as much as possible. Does disking soils that are “a bit too heavy to work” to air them out really make sense? Probably not. I like early planting, but you don’t have to be the first to plant in your neighborhood. Make sure the ground is ready, and you won’t be causing unnecessary soil compaction as you rush to get planted.
Control field traffic. Restricting traffic to certain lanes within the field should help in reducing soil compaction on most of the farm. Use controlled traffic and use the same path every year, if possible. Use the road, farm lane or headlands, if possible, when hauling inputs to the field. Strip tillage is a tillage choice that helps control traffic across the field.
Build soils with organic matter. Adding manure and other sources of organic matter can help improve soil structures and reduce soil compaction. Rotation with different crops and cover crops also helps. Look for crops with different root lengths and structures that explore different layers of the soil. For example, radishes as a cover crop grow more than 12 inches long and 1 to 2 inches thick. They can penetrate compacted layers and add organic matter. Plus, they hold nutrients during winter months.
Subsoil when necessary. If existing compacted layers are deeper than 12 inches, subsoiling is recommended. Then adopt healthy soil practices like those mentioned here to prevent soil from compacting again. Remember, soil compaction can’t be eliminated, so you must constantly work on reducing it.
Nanda is director of genetics for Seed Genetics Direct, Jeffersonville, Ohio. Email firstname.lastname@example.org or call 317-910-9876. Please leave a message.