Managing Soil Compaction During Corn Silage Harvest

Corn silage needs to be harvested at a precise moisture level to produce good results, so there is very little opportunity to postpone harvest when soil is really too wet to be on it. After that, manure needs to be spread.

Corn grain and soybean harvest are around the corner, therefore farmers need to work to make their soils resist compaction. They need to use equipment that causes minimal soil compaction, and as a means of last resort, be ready to repair any detrimental compaction that has been caused.

Farmers can make their soils resist compaction better by using practices that improve internal drainage and soil structural stability, increase organic matter content and biological activity, and maintain a permanent living root system in the soil. By using permanent no-tillage practices, soil develops a natural porosity in a relatively firm soil matrix. There will be permanent macropores that stay open, many of them created and maintained by nightcrawler earthworms, while decomposing roots of previous vegetation also leave pore spaces behind.

Nightcrawlers are favored by no-tillage, needing residue mulch at the soil surface. They live in 3-5 foot deep, vertical burrows that stay open, thus improving water movement through the soil profile. Deep taproots of crops like alfalfa in the rotation also help increase macropores into the subsoil. When the alfalfa is terminated, the roots decompose, leaving behind permanent pores coated with organic matter. Soil aggregation is improved by increasing organic matter content and the enmeshment of soil with fine roots. Thus it is important to find ways to add organic matter sources such as crop residues, animal manure, and compost. Cover crops add organic matter too and help to maintain living roots in the soil year-round. 

To avoid soil compaction, farmers should attempt to limit axle loads by using multiple axles on equipment or using smaller size equipment: bigger is not always better. The aim is to limit axle load to no more than 10 tons. Tires are also important. Tire inflation pressure should be kept as low as possible (check tire inflation tables). Variable Tire Inflation Systems are common in northern Europe, but not yet in the U.S. If we experience high soil moisture conditions during harvest times on a more frequent basis, it may be something to look into. Tracks are another possibility, but just make sure the tracks have many rollers to avoid high stress underneath the rollers. 

Finally, if everything fails and you do cause detrimental soil compaction, it is necessary to repair the damage caused. Ruts need to be repaired: I advise farmers to bust up the bottom of the ruts with some heavy-duty tillage tool like a subsoiler or chisel plow, then level the soil so crop production can continue. This needs to be done when the soil has dried out a bit. However, it is much preferred to avoid repairs and focus on avoidance. Remember to plant a cover crop after you do remedial work to restore aggregation and build structure back up.