"In some cases, it would take substantial increases in other rotational crops to make it pay," says Gary Bullen, North Carolina State Extension ag economist. "There is little data to verify the economic benefits of crop rotation for cotton growers."
In a recently completed six-year study, Bullen looked at rotation on three model farms in eastern North Carolina, taking into account what kind of yield increases would be needed to make the practice pay.
As with any practice on the farm, Bullen says it’s a matter of where rotation works best and when it pays to use it. "You can’t say, ‘Well, this crop will do well in rotation with cotton,’" he says. "You have to look carefully at what the yields have been and what the potential is for rotation. You can’t just say, ‘I’m going to plant wheat in rotation with cotton."
Bullen began the study at a time when North Carolina cotton acreage was on the rise. From 1997 to 2002, cotton acreage in North Carolina increased from 670,000 to 930,000 acres. Much of the new acreage is grown on a continuous basis.
He chose farms in Jones, Northampton and Hyde counties to simulate the net income effects of continuous cotton and four different crop rotations. Jones County was the only location in the study where cotton in rotation with other crops paid off on a consistent basis.
In Hyde County, nothing came close to continuous cotton.
And in Northampton, only the wheat-soybean rotation had a similar return when compared with cotton.
In Jones County, cotton was planted on at least 800 acres of the total cropland and tobacco on 100 acres for each of the six years. The additional 400 acres was planted to wheat, corn and wheat-soybean double-crop, soybeans or cotton. Using a 5 percent increase in all crop yields, three of the four crop alternatives — corn, wheat-soybean double-crop and soybeans — had a higher per acre net income than continuous cotton. Adjusted for a 5 percent increase in yield, continuous cotton had a net farm income of $104.85 over the six-year period; corn, a $115.76 net income; wheat-soybeans, a $119.52 net income; and soybeans, a $106.03 net income.
In Northampton, the leading cotton county in the state, farmers use peanuts in the rotation. The model farm had at least 750 acres of cotton, and 150 acres of peanuts, used in rotation, over each of the six years. The additional 350 acres was planted to the same rotation scheme of wheat, corn, wheat-soybean double-crop, soybeans or cotton. Using the 5 percent increase in crop yields, the wheat-soybean double crop in Northampton County had similar returns as continuous cotton, albeit at a lower rate. Continuous cotton in the county had a net income of $56.75 over the six-year period; wheat-soybeans, a $52.70 return.
In Hyde County, the model farm was larger than the other two. It had at least 1,667 acres of cotton, with an additional 833 acres planted in wheat, corn and wheat-soybean double-crop, soybeans or cotton. With a 5 percent increase in all crop yields, no alternative produced a higher net farm income than continuous cotton. Each rotation alternative had negative returns over the six-year period when compared with continuous cotton.