In the past, many growers may have shied away from the prospect of a sod-based rotation because they didn’t want the added trouble brought by cattle. But declines in commodity prices might change their opinions.
Kris Balkcom, research associate at Auburn University’s Wiregrass Research and Extension Center in Headland, Ala., is one of the researchers involved in a multi-year, multi-state project looking at the viability of sod-based rotations. The project has research sites in Alabama, Florida and Georgia and involves cooperation from state and federal agencies and several conservation groups. In Alabama and at one Florida site, cattle are used to harvest the grass produced as cow-calf operations. At the second Florida site and in Georgia, the grass is harvested as hay and seed crops.
The Alabama site, says Balkcom, is a four-year rotation with peanuts, cotton and two years of bahiagrass.
“We just can’t go out and change our soils overnight. It takes time for these cover crops and perennial grasses to work and build up organic matter,” says Balkcom.
One of the drawbacks to a sod-based rotation is some farmers don’t want cows, he adds. “When you do have cows, it means a lot more work for you. We do have a lot of cattle/row-crop farmers in the Wiregrass region, and they stay busy throughout the year, with something always going on. It’s either the cows or the crops all the time,” he says.
But being diversified is a plus, says Balkcom, because it spreads your risks, and a sod-based rotation with cattle gives you another enterprise.
“There wasn’t been much interest in sod-based rotations when commodity prices were so high. You could have made a lot more money with cotton at 90-plus cents or corn at $6 or $7. Now we’re sitting at $3.70 for corn and 60 cents for cotton. It’s a lot different now when we look at the future of these systems,” he says.
In the Alabama plots, explains Balkcom, plots were strip-tilled and turned. The impact of cattle grazing also was gauged, he adds.
“The data shows that we get a boost from the grazing due to the nutrient cycle. We want the benefit of cover crops to build organic matter, but what happens when cows eat the cover? That nutrient cycle is giving us a little yield bump there. We want to look at this further to see if we still can get this yield bump if we take away the cattle, for those producers who don’t want the trouble of running cows.”
Tillage impact seen
“Looking at four years of peanut yields, we see an improvement in yields where we used a moldboard plow in the sod-based rotation. On cotton, we don’t see a difference when we compare tillage. Farmers in our region were quick to adapt conservation tillage in cotton and corn but have been slow to adapt it in peanut production because we’ve always had a yield drag with strip tillage in the Wiregrass.
“But we do see the conservation tillage paying off and the sod-based rotation paying off. A lot of farmers are using GPS and doing grid soil sampling, and everyone has bad spots in their fields. We try to alleviate that, but there are spots that we can’t change no matter how much fertilizer we use. One of the ways to change those areas is to plant it in a perennial like bahiagrass; something that will change the organic matter.”
Bahiagrass is deep-rooted and can penetrate the hardpan, explains Balkcom. “It also helps us with our water infiltration. Some of our research has included looking at 1 inch of rain on these different rotations. On cotton after peanuts, it took 22 minutes for 1 inch of water to penetrate the ground. After the first year of bahiagrass, it was down to 20 minutes, peanuts after cotton was down to 13 ½ minutes, and with peanuts behind bahiagrass, that 1 inch of water was gone in 2.2 minutes. The bahiagrass roots deeply penetrate the ground, and it opens it up for our peanuts and cotton, giving us a higher water infiltration rate and helping us to get through a longer period of time between rains.”
Most Coastal Plains soils in the southeast portion of Alabama are 1 ½ percent or less of organic matter, says Balkcom.
“Over time here at the station, we’ve seen 2 ¼ percent with our sod-based rotation and strip tillage. This is one way to get a benefit. Even if cattle don’t fit into your operation – and cattle prices will cycle out just like commodity prices – I think the more diversified we are in our operations, the better off we’ll be in the long run.”
Cover crops also can benefit soil organic matter, especially the heavy covers that many farmers are beginning to use, says Balkcom.
“Small cover crops won’t last long in the South, and we won’t get much benefit from them. A good cover also will help you in the chemicals you have to use. It’ll especially help with glyphosate-resistant Palmer amaranth pigweed. In our research with a sod-based rotation, we saw only a few scattered escapes in the field, but it was nothing like a traditional rotation, especially where we turned the ground. All Palmer amaranth pigweed needs to thrive is sunlight and stirring the soil a little bit.”
A sod-based rotation also requires less fertilizer, says Balkcom. “Auburn University’s fertilizer recommendations for peanuts don’t call for much other than calcium requirements, but with cotton, we recommend 90 to 100 pounds of nitrogen. That’s a lot of expense when you consider the high cost of nitrogen. We were able in our trials to drop down to 60 pounds of nitrogen on cotton, and we’ve had years when we made three bales and better. Nitrogen was not a limiting factor.”