WILLMAR, Minn. — One thing that is a constant in conservation tillage is there will be residue of some sort on the field to consider.
At the Conservation Tillage Conference last month in Willmar, Dick Wolkowski, University of Wisconsin Extension soil scientist emeritus, walked producers through ways they might manage residue.
“Residue management, it’s complicated,” Wolkowski said. “You have to deal with what the combine left for you.”
Editor’s Comment: Soil health is at the core of a sustainable bioeconomy, especially when residues are removed from the fields. The article below provides food for thought, especially for Africa, where the soils are not necessary as rich as in the Northern Hemisphere.
Our business focus is on the beneficiation of agricultural residues that do not have a negative impact of soil health (e.g. corncobs, sunflower husks, rice hulls, sugarcane bagasse, etc.)
Given that, it’s a good idea to be conscious of combine settings and to change them if you want cuts higher or lower or for residue to be larger or smaller, Wolkowski said.
Other factors affecting residue management include soil moisture and accompanying compaction or rutting; equipment, especially the amount of residue the intended planter can handle; farm goals; whether there is manure or fertilizer to be applied; and even neighbor and peer pressure for the farm to look ‘normal,'” Wolkowski said.
Wolkowski is a residue fan for its soil-keeping properties.
“Crop residue is really your best erosion prevention tool,” Wolkowski said. “If a field is 30 percent covered, it can have a 60 percent reduction in soil loss.”
Erosion is a big problem in the Midwest and it’s cheaper to prevent than to fix, Wolkowski said. Practices like conservation tillage help prevent erosion. Soil can wash away in wet years and it can fly on the wind in dry years. Wolkowski cited 2012 as a good example of the latter. Soil loss by wind is higher than by water for North Dakota and Minnesota, he added.
That loss comes at a price. If one foot of soil is lost from a 40-acre field per year, that’s equivalent to 16 dump truck loads of soil leaving the farm annually, or $3,000 bought. On the reverse side, soil regenerates at 0.003 inches per year.
“It doesn’t seem sustainable,” Wolkowski said.
Stewardship should be the first consideration of residue management, Wolkowski said.
A nation that destroys its soils destroys itself (Franklin Roosevelt)
“What you do now is going to affect the future condition of the land,” Wolkowski said. He added a quote from president Franklin Roosevelt: “A nation that destroys its soils destroys itself.”
Wolkowski returned to the combines. Combines should size and spread residue, which modern machines are already set up to do. If residue gets chopped and then chisel plowed, there is less residue cover. Smaller pieces decompose more quickly. It’s better to retain some residue to decompose more slowly, Wolkowski said.
Bt corn stalks shouldn’t pose a challenge on the residue front, Wolkowski said. There seems to be a perception that remaining residue from the plants is less resistant to breaking down. However research out of Missouri, South Dakota, Nebraska and Switzerland has found that there is no difference in decomposition between Bt and non-Bt corn stalks.
Some producers may use fall-applied nitrogen to aid residue breakdown, Wolkowski said, but he hasn’t found the practice to be cost effective.
One residue concern Wolkowski sees on the horizon is the coming of cellulosic ethanol, which uses products like corn stover to make fuel. If too much residue is removed from the land, it can negatively affect grain yield as well as reduce the amount of carbon, nitrogen, phosphorus and potassium in the soil, Wolkowski said.
“It could be $25 to $35 per ton of nutrients you’re removing,” Wolkowski said.
Wolkowski expects there will be more interest in high residue systems as time passes. The practice has both stewardship and economic value, Wolkowski said.
His top takeaway for producers is that they shouldn’t plow soybean ground. He also encouraged farmers to foster an appreciation for proper soil resource management in young people. Other takeaways:
• There might be some light regulations in the future. Wolkowski is hoping they will be research-based.
• He expects there will be more of a push from companies regarding where food comes from and how it was produced, which may include pressure on erosion and water quality metrics.
• There is always room for improvement.
Source: Actively Manage Crop Residue