- Depending on its depth, spring might not be the best time to alleviate compaction.
- In shallow compaction conditions, soil amendments like Gypsum can aid in compaction management
- On fields with deeper compaction layers, deep tillage in the fall is the recommended practice.
If soil compaction is any deeper than primary tillage depth (6-8”), spring is not the best time to start worrying about compaction management.Deep tillage to alleviate compaction at this time of the year can often do more harm than good.The fracturing of the soil to a depth greater than primary tillage can lead to moisture from rains received to continually penetrating below the active root zone, until large gaps in the soil seal.
How do I determine compaction depth? Use a tile spade, tile probe or cone penetrometer. Layers of compaction are best determined when the soils are near field capacity.This is soil moisture content point at which excess soil moisture has drained away and drainage has stopped.When soil conditions are not perfect to test, careful use any of these implements inserted into the soil with constant even pressure can help detect compaction layers.The compaction layer will be indicated when insertion of the probe is slowed as passed through the soil profile. As the probe breaks thru the compaction layer there is often a sudden increased rate of penetration.
Are there soil amendments to aid with compaction? Yes, for shallow compaction.Gypsum can help alleviate compaction and water infiltration at shallow depths up to 8 inches when applied at much higher rates than necessary for corn or soybean nutrition.Rates between 1000-5000 pounds per acre are necessary to alter soil physical properties.Gypsum acts on clay particles much like detergent acts on dirt on laundry, causing the clay particles to expand and disperse.Contrary to some beliefs gypsum has no liming property; it is more a soil conditioner and sulfur source for crops.
In summary, spring is not the best time to resolve compaction zones deeper than 8” however, shallow compaction and soil properties can benefit from gypsum application.Gypsum application need to be 1000-5000 lb/a, with greater rates used on higher clay content soils. On fields with deeper compacted layers, plan deep tillage for a fall timeframe. Fall deep tillage allows winter freeze and thaw to penetrate deeper into the soil profile to further fracture soil and allow the soil profile time to settle.
Below: Soil compaction meter. Source: Ben Potter, agweb.com
