Inter-seeding Cover Crops into V6 Corn while Side-dressing Nitrogen

Keith Hartmann

My first objective is successfully establish a stand of annual ryegrass, oilseed radish and rapeseed into V6 corn while making an in-season nitrogen application. I will accomplish this by using the lnter-seeder/Side-dresser that I built in the spring of 2016 for the first year of my MN Corn Innovation Grant trials. During this past growing season, I established 28 plants/square foot or 85% germination using only 10lbs of seed per acre ($15/acres seed cost). That mix was annual ryegrass, oilseed radish, rapeseed, turnip and crimson clover. In my observations over the past 2 years, the turnips and clover have struggled with the residual herbicide and shade of the com canopy. I will be removing those in 2017 in hopes to improve stand establishment and potentially lower the seed cost. I would also like to modify the inter-seeder by replacing 4 of the 12 seeding units (Yetter Strip Fresheners w/ Firm wheel) with a coulter and seed tube. I would like to compare the cover crop stand of both methods. Using just a coulter and seed tube would be more cost effective than the strip freshener unit for a farmer to get started but, seed to soil contact would be reduced without the firming wheel, potentially slowing or reducing emergence. I like to look at it as possibly a Gold and Silver method.

I will again set up a replicated, full field length, test plot comparing the inter-seeded cover crop to no cover crop in the corn rows. I will be weighing corn grain yield at harvest and measuring stalk nitrate levels at maturity to monitor if the cover crop is taking nitrogen away from the com and yields to confirm if there was any difference. I will also again take soil nitrate levels at first killing frost. In 2016, I took a 12 inch deep soil core for the soil nitrate tests. After reviewing the results, I do not feel that was deep enough to get a good measure of the soil nitrate content that late in the season. In 2017, I intend to deepen that core sample to 24-36 inches depending on the soil probe capabilities. The corn yield will be measured using a certified weigh wagon, ensuring accuracy. The stalk and soil nitrate tests will be processed by Frontier Labs MN, LLC in New Ulm, MN.