Healthy soils are the foundation of our cropping systems. One of the most important attributes of a healthy soil is good soil structure. Due to the excess rainfall we have received this summer, the soil structure of our local farm fields is at risk of being destroyed by compaction this fall.
Soil compaction refers to a reduction in soil pore space. Healthy soils have a balance between solids – minerals and organic matter – and open pore space. For plants this pore space is critical because it allows for proper water infiltration and drainage as well as gas exchange between surface air and roots. When soils are significantly compacted and pore space is lost, crops become stressed and growth potential is lost.
Even though we know more about the causes and consequences of soil compaction than we did years ago, the risk of soil compaction is still high. Soil compaction can be caused by many things, including rainfall, but the primary concern this fall will be wheel traffic. As our equipment has gotten bigger, so are the loads that our soils are being exposed to. And, as soil moisture increases, so does the potential for those heavy loads to cause compaction deep in a soil profile. Combining these heavy loads with the need for farmers to get increasingly larger amounts of work done in small periods of time and we increase our chances of causing compaction.
The negative consequences of compaction are very real, can last for multiple years after the initial compaction occurs and often times are not easily corrected. Not only does soil compaction limit the exchange of water and gases, but it also makes root growth more difficult. If root growth is limited, plants may not be able to reach vital nutrients needed during growth.
The effects of compaction are not always bad, though. Seeds germinate best when there is adequate contact between the seed and soil. This contact makes water more readily available to the germinating seed. Corn planters have been designed to moderately pack the soil around seeds for years. If too much compaction occurs during planting though, all of the negative consequences described above come back into play.
So how can we deal with soil compaction? Avoiding working in fields that are too wet is the simple option. But this is easier said than done during busy harvest seasons. If you do have to venture out into a wet field, keep field traffic to a minimum and use controlled traffic patterns. Controlled traffic patterns use the same wheel paths for each piece of equipment, limiting damage to a smaller area of the field. When compaction has occurred and is going to be removed using tillage, be sure to use the proper equipment for the depth of compaction and the soils you have.
Remember, healthy soils are the foundation of our cropping systems. If we weaken that foundation, by destroying good soil structure through compaction, we limit our maximum crop yields for years to come. We also increase the potential for environmental degradation through lost water infiltration and increases in runoff and erosion. For the health of your soils and the health of your bottom line, keep compaction in mind when doing field work this fall.