UT Extension News: Drilling Vs Discing

July 6, 2021

By Chris Hicks, County Director – UT Extension Smith County

I had a question come through on email this past week that is one of those frequently asked questions without a one-size-fits-all answer. The question was essentially, “Which is better when establishing a forage crop: conventional tillage and broadcasting seed or drilling seed with a no-till drill?”

It’s a great question and the answer depends on the site, the equipment one has access to, and the time available. There are pros and cons to each, and at the end of the day it may come down to personal preference. 

Conventional tillage and broadcasting require more passes over the field, as well as equipment like a plow, disc, and cultipacker that someone may or may not have. It also requires more seed since you can’t really control seeding depth and need to bump up the rate to account for seed that gets planted too deep or too shallow. 

That said, it’s a good option if you have a fairly level field where erosion isn’t a concern or a weed-infested field where you want to use deep tillage to bury weed seeds deep enough they hopefully won’t germinate. Keep in mind that shallow tillage will bring previously buried weed seeds to the surface and you will have to spray them to avoid competition with seedling grasses. 

For best success with this method, plow/disc/finish at least 2-4 weeks prior to planting, and incorporate lime, phosphorus, and potassium based on soil test results. Being able to incorporate your lime by tillage is a nice advantage of this method, as it will change the pH faster than broadcasting lime on top of the soil. Allow time for the soil to settle or firm it with a cultipacker/roller. The seedbed should be firm enough your boot tracks aren’t deeper than ~1/4 inch when you walk through the field. 

Drilling with a no-till drill is a good option if you have land that might erode or don’t have the equipment for conventional tillage. No-till drills can be rented for a nominal fee from your local Co-Op, or larger farmers may choose to purchase one to have handy. What I like about this method is every aspect can be controlled precisely – rate of application, seeding depth, and row spacing. In one pass, the drill opens a furrow in the soil, places the seed in the furrow at a controlled depth, and then covers the seed.

It’s important to calibrate the drill beforehand rather than rely on the chart on the drill. UT has a nice video on drill calibration at utbeef.tennessee.edu. Make sure you get off the tractor and check the seeding depth periodically. No-till drills can plant the seed much deeper than it needs to be, especially in wet soils, and seed planted too deep won’t germinate. That’s probably the biggest reason for stand failure I see with drilling. 

With no-till establishment, you’ll have best results by killing existing vegetation before planting by spraying glyphosate or paraquat. If it’s a decent stand of grass (>50% stand) you are just wanting to thicken up, you might skip this step and instead clip or graze it as close as you can prior to drilling. Be sure and control broadleaf weeds prior to planting.

With either method, fertilizing according to soil test results is essential. Also, your seeding rate, depth, and planting dates are critical components. UT recommendations for most all forage species can be found in our publication “Forage & field Crop Seeding Guide for Tennessee” which is available at the UT Extension office or online at  smith.tennessee.edu