Check Soils for Compaction Layers
Josh Copes, Dennis Burns, R.L. Frazier, and Dan Fromme
Over the past couple of growing season, soil compaction has been a hindrance in many fields across Louisiana. Soil compaction was evident by observing reduced crop growth and development in fields and confirmed by inserting a penetrometer into the soil. Soil compaction is the compression of soil particles that reduces pore space thus creating a dense layer of soil that can impede plant root growth. Soil compaction can be caused by heavy machinery traffic and horizontal tillage operations when the soil is too saturated. There have been instances where a deep vertical till implement was used to alleviate a soil compaction layer only to create a new one, less than four inches deep in the row middle, when the rows were rebedded. This was probably a result of rebedding when the soil was too wet. Soil compaction reduces crop rooting ability, restrict water infiltration rate, reduces the volume of soil that plant root will be able to mine essential nutrients, and ultimately can reduce yield.
Machinery size is steadily increasing and will only lead to more frequent soil compaction issues. Silt loam soils are typically prone to compaction. There is perhaps a misconception that shrink and swell type clay soils are not prone to compaction layers due to being “deep broke” as they crack open during periods of drought. Regardless soil compaction layers have been observed in cracking clay soils. Fields where soil compaction could be an issue can be identified by visual observation where a reduction in crop growth rate is evident, early season nutrient deficiency symptoms occur, wilting of crops in certain areas of the field and not in others. Compactions areas can especially be identified during periods of cool weather early in the growing season where the crop develops at a reduced rate compared with the rest of the field with a similar soil type.
You can test for compaction layers by simply probing the soil (tops of beds/rows) in several areas within a field using a soil penetrometer. In order to mark the depth of the compaction zone, push the penetrometer down to the compacted zone and place a finger where the probe meets the soil surface. As a guideline, use the penetrometer when there is sufficient soil moisture for planting. Also, make sure that deeper soil compaction layers are not present. To avoid soil compaction limit field operations when soils are too wet. This can be difficult in Louisiana but creating hardpans will reduce yield. Deep vertical tillage is the fastest method to alleviate soil compaction layers. Deep or tap rooted winter cover crops can also help loosen a compacted soil over time and may help prevent a compaction layer from occurring by increasing soil organic matter and maintaining soil structure.
Below are some photos taken this year in fields with compaction layers. Fields with soil compaction layers should be identified and deep broke this fall when soil moisture conditions are favorable to lift the soil so the hardpan can be disrupted. If you have any questions or concerns please give us a call.
Photo 1. J-Rooted Cotton due to Soil Compaction Layer