When cotton seed cost $350 per ton, the rule was to plant heavy and thin the stand later on if you needed to. But when seed hit $500 per bag, you sort of had to find a new rule book.
“Everyone with anything to do with cotton farming is aware that the genetically modified varieties have had a very big impact on agriculture. They have allowed us to improve our weed and insect control,” says Dr. Earl Vories, a USDA/ARS agricultural engineer at the University of Missouri Delta Center in Portageville. “But along with that, the cost has gone up, and there have been a lot of questions about what we can do to make sure we’re not wasting seed.”
So the research hypothesis becomes finding ways to minimizing seeding rates while maximizing yields. The most visible means to that end at the moment is site-specific, variable-rate planting, and the ability to do just that is already available.
“I am very confident in saying that we have the mechanics, the hardware, and even the software in place. If someone wants to variable-rate plant, the technology is there,” says Dr. Edward Barnes, Director, Agricultural Research at Cotton Incorporated.
What we lack, though, is the definitive data required to write the prescriptions. “One of the things that makes it difficult to say exactly how much benefit you can get with precision planting is that cotton is a great compensator,” Barnes continues. “Cotton can absorb a lot of variability in seeding rates, so it makes it very hard to collect the data it takes to make strong decisions on variable-rate planting.”
Vories agrees: “We don’t have economic data that would make us say with confidence that this is the way to go – we’ve only been working on the data for one year. … We as researchers are behind the equipment that is available. The technology to make the adjustments is there. But right now, our recommendations can’t match up with the equipment capabilities.”
Data Quest Begins
Most prescription-based applications of farm inputs starts with soil-type and yield-monitor maps.
“(Farmers) know what’s going on in a field. They know the highest yielding areas, and the lowest yielding areas,” says Vories. “One of the reasons we were able to start work on precision planting is because we are getting so much information from yield maps and Veris EC data.”
What’s lacking at the moment is an understanding of how the relationship between soil types and planting rates impacts yields. Frank Groves, Cotton Verification Coordinator for the University of Arkansas Cooperative Extension service has completed one year of research, and through a grant from Cotton Incorporated, will begin another three-year trial.
“We are looking at two varieties at low, medium and high seeding rates on variable soil types in three different locations in the state,” Groves says. “Ultimately, what we are shooting for is to be able to have a prescription that will fit each soil type as the planter moves across the field.”
The plots will run across light, mixed and heavy soils. Then each 12-row strip will be planted with one of five seeding rates.
“We are using a variable-rate planter, and we have a prescription, but we’re not changing it according to soil texture in this study,” says Groves. “When we harvest the plots, we’ll be able to lay the yield maps over the zones and see what seeding rate looked best in each soil zone.”
Irrigation can also impact prescriptions. For instance, there would be one seeding rate for areas of a field covered by the main span of a center pivot, another rate for the area covered by the end-gun, and yet another for areas not watered at all.
“Once we synthesize all of the information, we’ll be ready to go,” Barnes says. “Ideally we want a turn-key system that, based on the data points on soil type and yield, will give a farmer a variable-rate planting prescription that a researcher would be proud of.”
Groves agrees: “Absolutely. That is what we want to wind up with. With seed cost being what it is, ultimately our goal is to plant only as many seed as you need to.”