By Zachary Larson, Field and Forage Crops Educator
Cereal rye is widely used due to its ability to establish late in the season and can still be successfully established in most of Pennsylvania into October. In dry years, when lower than expected yields result in un-captured soil nitrogen (N), N-scavenging plants such as cereal rye can be especially important in consuming excess nutrients and releasing them the following spring. However, the traditional seeding rate of 2 bushels per acre should be more closely reviewed, with spring management objectives helping to determine seeding rates.
Know Your Seeds per Pound
A study of rye planting dates at the Big Flats Plant Materials Center in New York showed seeds per pound for rye varied from under 12,000 to over 33,000 based on the cultivar. Assuming traditional small grain seeding rates of 1.5 million viable seeds per acre and a germination of 85%, pounds of seed per acre would vary from 53-147 to hit the 1.5 million seed mark. While many older cultivars may have been accurately planted at 2 bushels per acre, knowing your rate of seeds per pound and the germination rate of the seed can better help determine how many total pounds should be hitting the field.
Follow Traditional Seeding Rates for Late Planting and Early Termination
The traditional seeding rate of 1.5 million viable seeds per acre is still a good starting point for establishing adequate ground cover when rye is planted later in the fall or in northern areas of the state where little fall growth is expected. This is particularly true when termination is performed well ahead of planting, when plants are younger and shorter. So if you’re managing rye for winter cover and are terminating early, you may only need to consider seeding at rates of less than 2 bushels per acre when your number of seeds per pound is above 16,000.
Less May Be More if You’re Applying Manure
A study of three rye planting rates and three poultry litter rates in Pennsylvania and Maryland showed that poultry litter application had an effect on rye biomass while planting rate had relatively little effect. In this case, biomass yields were similar at seeding rates of 80 and 186 pounds per acre when litter was applied. So for those applying manure to rye this fall or in the spring, a lower planting rate may be acceptable for achieving high forage yields, providing erosion control and meeting soil health objectives.
More May Be Necessary if You’re Looking for Weed Control
The same study showed that the increase in seeding rates from 80 to 186 pounds per acre resulted in greater weed control when the rye cover was rolled and crimped. This was likely due to increased ground cover early in the season, owing to greater plant density. A commonly accepted target for good weed control from rolled and crimped rye is 7,000-8,000 pounds per acre of dry matter, which can be achieved with 1.5 million viable seeds per acre, with planting dates as late as mid-October, depending on location and termination date in the spring. However, it should be noted that rolled and crimped rye may not suppress all weeds and that follow-up treatments may be needed later in the growing season.
Higher Rates May Not Be Necessary if Soil Health is Your Objective
For those looking to use a late terminated rye cover as a means of maintaining living roots throughout the year and improving soil structure, higher seeding rates may not be as important. Veteran no-tillers that use rye as a soil health tool may go as low as 30-60 pounds per acre, although due to smaller seed sizes, some may still be planting close to 1 million seeds per acre. Those that plant at lower rates cite reduced input costs, improved light penetration and airflow to the soil surface resulting in quicker drying in the spring and ease of planting when going into a standing cover crop, commonly referred to as “planting green.”
So before the drill hits the ground this year, determine what your objectives are and what seed you intend to plant. Depending on your rotation, need for spring forage and manure application practices, you may even want to use multiple planting rates. By considering your needs and resources now, you can better obtain the ideal cover crop stand when spring rolls around.