Let's Talk Legumes - Cool Season

Amanda Rollins, October 1, 2019

 Did someone say nitrogen credits? How about forage quality? Cool season legumes can provide both! Here are our favorite legumes to plant when the summer heat subsides:

Winter Peas

       In forage or cover crop blends seeded in August to early September, winter peas can be your go-to for generating nitrogen. These cold tolerant, bad boys can fix anywhere from 90-150 lbs of N per acre when given ample time to grow and nodulate. That “ample time to grow” can vary based on temperatures, but is important to remember when estimating the amount of nitrogen credits you are actually getting for the next crop. But don’t get caught up in just the nitrogen, these plants will also condition the soil with their roots and provide excellent feed quality.

       Seeding Rate = 50 lbs per acre full rate, 10-30 lbs per acre in a blend

       Seeding Depth = 1-2 inches in a blend

Lentils

       Ah, lentils. The even more cold tolerant cousin of winter peas! These will be your latest planted legume at they are most able to withstand weather extremes. While they aren’t indestructible, established lentils will be able to hold up against a few frosts. The roots of lentils are great for creating connections with mycorrhizal fungi and assist with water infiltration. Lentils can also be your early spring planted cover crop for green manure or forage, when weather permits.

       Seeding Rate = 20-30 lbs per acre full rate, 10-20 lbs per acre in a blend

       Seeding Depth = 1-2 inches

Faba Beans

       Whether you spell it with a “b” or a “v”, it doesn’t matter. Vicia faba is a plant that does a little bit of everything. Pollinator benefit when flowering? Check. Vigorous tap root? Check. Tall, stalk-like growth? Check. The only down fall of this legume is the seed is so big! That being said, it can work well in a blend to fit the slot of cool season legume with attractive advantages and nitrogen fixing ability like the other legumes.

       Seeding Rate = 60-75 lbs per acre alone, 10-30 lbs per acre in a blend

       Seeding Depth = 1-2 inches

       Fixing nitrogen is a super power of these legumes, but where do they actually store that nitrogen? Within plant tissues, meaning the full plant has to be left whole to break down and release the nitrogen back into the soil. While mechanically harvesting these crops can provide great feed, you have to take that removal of the top of the plant into account when figuring how much it is giving back. You will still have the benefit of the root breaking down to release some nutrients back into the soil. For grazing, many of the nutrients will still go back into the soil after they pass through your livestock. Keep this in mind when balancing the forage vs. soil building goals of your legume!