When buying cover crop seed, do you check the seed tag? Even though you don’t plant cover crops intending to harvest a cash crop, it’s still important to pay attention to seed quality. Seed quality attributes include purity, vigor, germination rate, weed seed percentages and “trueness to its variety.”
A variety is distinct, uniform and stable. How fast a seed breaks dormancy in the spring, how long it takes to mature, disease resistance and plant physical size are all characteristics that differentiate varieties.
If you don’t state what variety you want, the default will be VNS, or “variety not stated.” Essentially, this is usually a mix of numerous varieties. This can cause problems if you’re expecting all plants of a cover crop species to act similarly. For example, if one variety of cover crop breaks dormancy before another variety and they are all mixed together, you may spray too early just to terminate one variety and then have to spray again for the other varieties.
Successful users of annual ryegrass across Indiana have found there are several varieties that survive Indiana winters but will terminate in the spring when published guidelines are followed. Do your research and choose wisely.
Different varieties of cereal rye also have different characteristics. These differences can impact how and when you terminate the cover crop, and how the cover crop protects against erosion or fights soil compaction. If you want to roller-crimp rye to terminate it, you’ll be better off using a cereal rye variety instead of VNS, so the rye all matures at the same time.
Cover crop seed trade-offs
Some farmers have tried growing their own cereal rye seed. Data from the Office of the Indiana State Chemist shows that you need to spend some time with a pencil and calculator to see if there is an economic benefit to doing this. Growing cereal rye for seed isn’t as simple as planting and combining. High-quality rye for seed requires a heavier seeding rate, plus application of nitrogen both for quantity as well as to improve the germination rate. Indiana’s high humidity often results in needing fungicide.
Data gathered by OISC shows that Indiana-produced rye can test as low as 50% germination. The goal is 70% or higher. The germinated rates for rye grown in low-humidity areas usually averages at least 70% and can be over 90%. Extra costs of additional seeding rates, nitrogen and fungicides, along with seed cleaning, could mean no economic advantage to raising your own rye seed.
If you wish to raise your own cereal rye or purchase it from a local source, Donovan says you need to have the seed cleaned, labeled and tested for germination with OISC, especially if you’re enrolled in a cover crop cost-share program. This will ensure you’ll be planting the correct amount of viable seed to produce the results you wish to obtain from your cover crop.
Most cover crop cost-share programs administrated in Indiana require that you provide seed tag information as documentation before payment is approved. More information on seed law in Indiana can be found at oisc.purdue.edu. For more information on the use of cover crops, contact your local Natural Resources Conservation Service or soil and water conservation district office.
Donovan is a district conservationist with NRCS in Parke County, Ind. He writes on behalf of the Indiana Conservation Partnership.