I am looking suggestions how to determine seeding rates and seeding depths in a mixture of various crops with different seed sizes to be grown as a cover crop in big field assume 500 ac? I knew the small seed size such as canola should be shallow compared with other big seed size such as corn when planted in a monoculture. But the challenge is when they are in a mixture, particularly when we have several seed sizes in the mixture. In addition, I feel that seeds may not be uniformly distributed in the field while planting big field due to seed segregation in the seed box because small seed size may come first than the big seed size. Please share any experinces and suggestions.
Thank you,
Yesuf
Dear. Yesuf. If the seeds are separated you can seedling the large seeds before small seeds
Your concerns are well founded and reasoned. Use a precision drill and make sure you have a packer for seed contact for the small seed. Plant a little deeper than normal for the small seed which will be shallower than normal for the larger seed. Make sure you have a reliable rainy period shortly after your planting time and schedule an irrigation to make sure of the initial establishment. Seedling establishment can favored by developing a well tilled fine seedbed and ensuring the initial weed population is well controlled. When establishment is considered marginal use a high seed rate from the seeding range. Heavy cover crop rates favors the biological control of weeds as they are more easily smothered. In organic farming the success of the main crop is generally determined by the farmers ability to optimize the cover crop. The ability to control weeds in organic farming is heavily dependent on thick development of the cover crops.
Dear Paul,
Thank you very much for the suggestions. Very good point. With regard to the seeding rate, if I use two crop species in a mix, I am thinking to use 50% of the recommended seed rate for the respective species when planting monoculture to make it more logical. If I use four crop species in a mix, then this will be 25% instead of 50%. I think this will make sense for the producers as well.
Yesuf
Hi Yesuf, I would add to this discussion thread that it depends on the status of your soil (cultivated or not, soil type). Also, how many species of cover crop are you considering (2-3, or more)? Soil moisture as Paul indicated is a critical condition in order to have the highest cover crop density. Regarding seed of different sizes and planting depth I would say that if the soil has been reduced to a fine tilth the broadcasting could be followed by the passing of a rolling cylinder that will lightly push the seed into the soil. Hopefully, your cover crop establishment is done at a year period when rain precipitations are going to occur. Check out also the book: Cover crops for the Northeast US Region. By Marianne Sarrantonio. The ATTRA sustainable agriculture web site has also a lot of information about cover crops. Select the link here below and then search for cover crops.
https://attra.ncat.org/
Dear Bruno,
Thank you very much for your comments. We will be uisng no-till drill to estabilsh the cover crops. I am convineced to seed them a little shallow but when there isenough moisture.
Thank you Yesuf!
Check out also Fred Magdoff & Harold Van Es soil book, which I am attaching here. Chapter 10 (pg. 101) is all about cover crops.
You have identified a world-wide issue of equipment designed and manufactured for seeding monocultures. Multi-functional cover crops are seldom monoculture. Since seed segregate, especially through vibration, going across fields, consider segregating before planting. If you are buying standard cover crop mixes, it will not work. On my ground this spring, I have a cover crop trial on 35 acres to eliminate grasses in cover crop preceding next year's corn. The six species (2 annual clovers, collard, radish, turnip, and forage soybean) had a seed count ranging from about 200,000 seeds per pound down to about 3000 for soybeans. It is impractical to segregate every species based on seed count. A neighbor with a 7 1/2 inch-row air-seeder had experience with cover crops and agreed to have one seed hopper for large seed (soybean) and one for small seed (~50,000 to 200,000 seeds/lb.). Part of the objectives is to select seed that could all be planted about the same depth. (In my case shallow planted.) My crop is just emerging but appears uniformly mixed. I am also interested in other practical experiences, and found these two sources helpful https://onpasture.com/2015/09/21/cover-crop-mixes-seed-size-counts/ and https://www.greencoverseed.com/.
Dear Mr. Wietgrefe,
Thank you very much providing practical solution. Yes, the use of two seed hoppers is best solution to minimize seed segregation. Do you get uniform plant stand due to shallow seeding? If you have enough moisture then this should not be a problem. I am trying this practice in a place where moisture is limiting.
Yesuf
My farm averages 18 1/2 inches moisture per year and we must no-till to conserve moisture to raise a corn/soybean rotation. Limited moisture is always a concern, but small seed always needs to be planted shallow relying on soil or light surface moisture to allow germination. Broadleaves, like forage soybeans, along with covers and others small seeded mixtures also can be planted shallow, whereas corn for example must be planted deep (1 1/2 in.) to allow proper root set. In cover crop I'd hedge toward shallow planting (1 in.) and have good weed control before emergence.
Mr. Wietgrefe,
Thank you for your explanation. The place where I am, we usually receive not more than14" a year. Cover crop supposed to have minimum input/low maintenance. Do you use chemicals to control weeds in cover crop? Do you use your cover crop for animal feed (grazing or haying)? There is a kind of confusion in cover crops. Some say we are not supposed to use it for other benefits than covering the soil other scholar says it is ok to use it for animal feed to bring immediate economic benefits. What is your opinion?
Thank you.
Yesuf
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