Soil Health and Corn Research

A new trend emerged at the CTTC conference last month. At least one third of presentations had soil health, regenerative farming, or cover crops in the title. A big change in farming practices started with soil and health and cover crops from 2010-2020, but that trend has slowed down. Was it just a fad?
The last 3-5 years have been tough. Dry weather and volatile crop and input prices makes change difficult. Slowly, more research is being started and a new generation is interested in soil health and regenerative topics. More farmers and researchers are looking at the advantages and disadvantages of new farming techniques.

Dr. Oslo Cotez, a new OSU cover crop and corn production specialist is researching this change. Dr. Cortez says the biggest problem with farmers planting cover crops is getting them seeded and established after harvest. He is actively researching farmers transitioning to no-till and cover crops.
Dr. Oslo has set up several long-term field scale sites throughout Ohio. He has three crop rotations with corn (c), soybeans (s), and wheat (w): c-s-w, c-c, c-s. He has two tillage systems, conventional tillage (vertical tillage 3-6 inches deep) versus strip till (80% no-till, one 6-inch strip tilled). For nitrogen, he has a high rate at 240# N compared to a 200#N rate. On cover crops, he has either cereal rye or no cover crop. Each farmer makes his own decisions within their own farming operation on when to plant, varieties, other decisions, so it is not a perfect comparison. Each farmer is trying to maximize his production and his profit.

You might ask, why cereal rye as a cover crop in corn? Both are grasses and both require more nitrogen to grow well. Why? Cereal rye is the most popular cover crop and many farmers are using it. Cereal rye can have an allelopathic (negative effect) on weeds but also corn growth.
Here is a tip: In corn use a low allelopathic cereal rye variety like Aroostock (Michigan), Elbon, Wren Abbruzzie or Meton. On soybeans, use a high allelopathic or common cereal rye variety because soybeans can take it.

Here are Dr. Cortez 2024 results. On tillage, no difference in yield for corn, however on soybeans the yields were slightly lower (40 bu conventional soybeans, 37 no-till). Due to wet early spring then dry summer, the soybeans in the cereal rye got planted later.

On nitrogen, no-till had slightly higher yields in both low and high N rates. On crop rotation, no-till did slightly better in both corn and soybeans in the rotations. On cover crop (cereal rye), no difference on corn but soybeans yields were slightly lower. Dr Cortez says it was difficult to get the cover crops planted on time. Individual plots varied on when the cover crop was planted and established. From research and other test plots, typically it takes 3-7 years to see big changes and these plots are only 3 years old. The 2024 year had delayed planting, a dry summer, and corn yields were in the 130-140 corn bushel range with soybeans 30-40 bushels.

Jonah Van Rockel, Dr. Cortez graduate student is doing a study on barriers to cover crop adoption. He is looking for farmers in the Maumee watershed or 14 Northwest Ohio (NWO) counties. Only about 5% of farmers are using cover crops in NWO. Jonah is collecting information off of 60 fields and he is looking for more fields to study. He needs four types of farmers: 1) Zero history of cover crops, 2) Winter wheat in the rotation, no cover crops, 3) cereal rye fields at least 1 of 3 years, and 4) More than 5 years of using cereal rye.

His results so far on 60 fields: On corn and soybeans no negatives to using winter wheat or cover crops on crop yields so far. On Soil Organic Matter (SOM) no differences. On carbon dioxide respiration (CO2, an indication of good soil health), early spring had higher levels of CO2 in cereal rye. On CO2 emissions, a greenhouse gas, slightly higher on cereal rye fields. More carbon dioxide may translate into higher crop yields but may increase greenhouse emissions. The same for Nitrous Oxide emissions (greenhouse gas), slightly higher with the cover crop. No changes in the soil health score card yet.

A few comments: Corn likes nitrogen so why not add a legume to your cover crop mix. No-till Cereal rye plus a legume (crimson clover, hairy vetch, Balansa) or a mixture of cereal rye plus oats with a legume would be helpful. Corn also needs more N up front to help stabilize the carbon dioxide emissions.