As I write this, we’ve had some substantial rain lately, with more forecast in the near future. This time of year, everyone is ready to put winter behind them, and turn the page to another growing season. One of the first activities in the spring is tilling the soil for spring planting. However, damage can be done rather quickly by getting into the fields when soil is too wet, causing soil compaction.
Soil compaction occurs when soil aggregates and particles are compressed into a smaller volume. As soil is compacted, the amount of open pore, or void space, decreases and the density, or weight of the soil increases considerably. Excessively compacted soil can result in problems such as poor root penetration, reduced internal soil drainage, reduced rainfall infiltration, and lack of soil aeration from larger macropores. Most soil compaction occurs from machinery being driven over a field when conditions are too wet, and may lead to reduced yields of 10-20%.
To determine whether your soil is dry enough to work, a simple test can be performed. Using a trowel or a spade, dig a small amount of soil and squeeze it in your hand. Does the soil stick together in a ball or crumble apart? Soil that crumbles through your fingers when squeezed is ready to till. If, however, the soil forms a muddy ball and will not fall apart, give the soil another few days to dry, and sample again later.
If you suspect you may have soil compaction, a tool called a penetrometer may be able to help you determine your depth of soil compaction. Based on the depth and severity of compaction, you will be able to identify corrective measures. Some of these measures include deep tillage, and more recently, the use of cover crops.
For more information on soil compaction, see http://extension.psu.edu/agronomy-guide