Part 4: How Should I Plant My Hay Field or Pasture?
What’s the best means of seeding fields, no-till or conventional tillage (a prepared, weed-free, firm seedbed)? As with any choice, there are advantages and disadvantages to each method. Both seeding methods allow for weed control activities before seeding but no-till is limited only to herbicide applications. Whenever deciding on an herbicide to use, read the label carefully to be sure there are no rotation restrictions of what can be seeded following the herbicide application or how many days or months must separate the application and seeding activities. Also use the label to determine if a single application will be all that is needed or whether you will need follow-up applications and if you will at what stage of growth must the new seedlings reach before the next application is applied. This latter concern is especially important for perennial and hard to kill weeds such as hemp dogbane, Canada thistle, horsenettle, and others.
No-till drills must be calibrated properly to deliver the correct amount of seed per acre as well as be set to place the seed at the correct seeding depth with adequate soil to seed contact for fast germination and emergence. Never assume that the last person to use the drill set it up properly for your seeding. When you spend a hundred or more dollars per acre just for seed, you need to be sure the seed is being planted as best as possible to ensure a successful establishment. No-till drills also place the seed in rows usually from 7 to 10 inches apart so it often is useful to cover the seeded area in two directions making a cross hatch pattern over the field to help the plants fill in the space quicker. Brillion seeders that broadcast seed over a prepared seedbed and then press the seed into the soil have the advantage of achieving canopy closure much sooner than no-till seeding.
Canopy closure is when the new plants get large enough that they are able to shade the underlying soil and therefore reduce the ability of weeds from germinating and establishing in the field. Fields seeded with no-till drills can be many years (if ever) filling in so that a full canopy exists during normal grazing activity. This is one disadvantage to the no-till drill although it is offset by the soil conservation advantage of no-till when a field has enough slope to allow significant water erosion or enough exposure to allow wind erosion problems if the weather turns dry again.
Which method is best? Since each has both advantages and disadvantages, it will depend on your situation. No-till helps conserve the soil in situations where soil can be loss; it reduces moisture loss since the soil is not disturbed; it doesn’t encourage new weed growth since buried weed seeds are brought to the surface; it does not introduce oxygen into the soil causing the soil organic matter to be reduced via oxidation; and when done correctly it ensures rapid germination and emergence since seeds are placed in the soil and soil is firmed around the seeds. From the negative side, no-till does not allow nutrients and lime to be worked into the soil profile; no-till does not help break up compaction issues from previous grazing or haying equipment use; and no-till seeding is often in rows that can be seen for years in some cases.
Conventional tillage does allow nutrients and lime to be incorporated in the soil; it allows tillage during the summer to help with weed control issues; it allows for the summer establishment of annual smother crops for weed control and to introduce organic matter into the soil; it allows you to rip fields to help alleviate compaction issues; and it allows seed to be broadcast to ensure rapid canopy closure. Some of the disadvantages include the loss of soil moisture during the tillage operation as well as the loss of soil organic matter during tillage. The above lists of advantages and disadvantages are not meant to be exhaustive but to point to some of the important factors you should consider when deciding on seeding method.
This article was submitted by Dr. Richard Taylor, Extension Agronomist, University of Delaware. Dr. Taylor can be reached at firstname.lastname@example.org