Every row tells a yield and nutrient uptake tale
The last harvest is 88 years away, and Wayne Ebelhar knows he’ll never bring in the final crop. He is 12 years into a 100-year look at crop rotation practices with measurable results pointing to the bottom line.
While chasing markets, farmers see dollar signs and profitability numbers as the only way to change opinions on farming practices. However, solid data stacked over multiple years shows the peaks and troughs of a consistent rotation system.
When Ebelhar, an agronomist with Mississippi State University (MSU), began the Centennial Plot program in 2004, he wanted to quickly build a production database with corn, cotton and soybeans. His system is unique: four replications and 15 combinations going at all times. An 8-acre area at the Delta Research and Extension Center in Stoneville, Miss., is divided into 60 plots and 240 subplots.
“Having this number of observations allows us the opportunity to assess natural variation in the field. Many of the long-term studies around the country only have years as replications. I’m getting four replications every time, with an additional four subplots inside, and that means 16 observations at the same time,” Ebelhar explains.
Ebelhar grows top GMO varieties with furrow irrigation, single-row corn, single-row cotton and twin-row LibertyLink soybeans on beds. The shift to LibertyLink was necessitated by glyphosate-resistant weeds. He uses the latest technology in fungicides, seed treatments and soil sampling.
His main focus is on the rotation effect on nutrient removal and yield. Ebelhar tracks removal of nitrogen, phosphorus, sulfur and potassium. Despite a dramatic rise in yields, he often finds corn and soybean farmers underapplying fertilizer. Consistent withdrawal from the soil bank without resupply is a losing proposition.
“We’re looking at tremendous nutrient uptake with high yields in corn and soybeans. After 12 years, if we show 2,600 lb. per acre of potash removed, the figure hits home with farmers,” he says, taking careful measure of the practical effect of a crop switch. “If I made 1,000 lb. per acre of cotton in a continuous cropping system and I made 1,200 lb. per acre in rotation following corn, I take the target price of 65¢ and do the multiplication. Evaluation is plain and simple.”
The only sure bet with commodity shifts is there’s another coming. The Centennial Plots help prepare farmers for the shifts, says Bobby Golden, MSU Extension soil fertility agronomist.
“It’s very powerful for analysis over time. You can go back and see the yield increases to trace the monetary benefits to a farmer over time compared to other rotations,” Golden says. Multiple years of data showing yield benefits of a particular rotation, combined with nutrient drawdown results, weigh heavy when a farmer considers soil test ramifications of altering the rotation, Golden adds.
“We’re dealing with crop systems that don’t change rapidly, and the Centennial Rotation research is needed to characterize those changes,” echoes Larry Oldham, MSU Extension soil and water quality specialist.
Producers see the bottom line, and Ebelhar’s research connects yield gains with dollar figures. “Rotation is the way to go,” he says. “Rotate chemistries for disease and insects. Plant crops with different root structures. Recognize the different levels of nutrient removal. All of that together means profit and that’s what the research plots repeatedly tell us.”