Planting into Cover Crops

Today’s guest post is from Mark Licht, Assistant Professor with the Department of Agronomy at Iowa State University and Extension Cropping Systems Specialist with ISU Extension and Outreach.

Spring planting is several weeks away. However, before long, planters will be coming out of hibernation for pre-planting maintenance. This is a good time not only to get the planter in top condition but also to think about considerations for planting into cover crops.

planting-corn-or-soybeans-following-a-cover-crop

Planting corn or soybeans following a cover crop is not business as usual. Even farmers who have been no-till for a long time indicate planter settings must be adjusted. The same criteria need to be met whether planting into cover crop residue, high-residue, or low-residue situations. Focus on attaining optimal seed depth, make sure the seed furrow remains closed, and reduce risk of compaction from too much row unit down pressure and sidewall smearing. This sounds easy and straightforward, however, often times planting into cover crop residue fails for these reasons.

Sidewall compaction occurs because cover crop residues reduce soil water evaporation, increasing the time needed for soil drying prior to planting after spring rains. Shallow and variable seed depth is due to lack of row unit down pressure, while too much down pressure creates a compacted zone beneath the depth gauge wheels, potentially resulting is poor root development. Seed furrows reopen as a result of not enough pressure on the closing wheel.

feb-img_0393Knowing when soil conditions are ready for planting requires taking the time to check soil conditions. Remember, it’s not what the surface soil conditions are, it’s the soil conditions where the seed is placed. Make sure double disc openers on the planter still have a bevel and have 1.5 to 2.5 inches of contact. Row unit downforce should be enough to place the depth gauge firmly in contact with the soil yet should allow it to be turned by hand. Closing wheels should be checked to make sure the furrow closes again. In wet soils, too much pressure on the closing wheels cause problems.

Mark Licht