As November draws to a close, fields have been prepped for the upcoming seasons. For many, that includes getting fields tilled for next year.
While no-till farming has become more prevalent for increased soil health, tillage is still a dominant force in agriculture. However, that doesn’t mean conventional tillage doesn’t have ways to limit soil erosion.
Richard Cruse, a soil management agronomist at Iowa State University, said any form of tillage will weaken the soil bed, but ultimately rain will be the biggest cause of erosion.
“Any time we till, we weaken the soil structure, which means it is more prone to collapse from raindrop impact forces, tires or any of those things,” Cruse said. “About 40 inches of water falling has the energy equivalent of about 4.7 tons of TNT. That energy is incredibly effective at destroying the soil structure on the surface, which really restricts infiltration, meaning more runoff and increasing the potential of erosion.”
Cruse said one key for those looking to limit erosion is leaving residue on the soil surface. Using equipment that will keep crop residue throughout the tilling process will leave more area for rain to be absorbed, rather than hitting the soil and running off.
If it’s not possible to leave residue, Cruse said it might be more beneficial to wait until late in the fall to run through the fields.
“The longer you wait the better,” Cruse said. “Then you’ll have a longer period of surface cover. If you are tilling early, you are more susceptible to the short, warm periods, rapid cooldown and big thunderstorms which are drivers for soil erosion.”
Dennis Flanagan, a research agricultural engineer with the USDA and National Soil Erosion Research Laboratory, said tilling in a way that the surface remains covered, such as vertical tillage, makes it less critical when the tillage occurs. He also said farmers who combine tillage and cover crops will want to focus on early tillage so there is more time to allow cover crops to take root and build biomass.
“You certainly want to leave as much residue as you possibly can, and if you are giong to some type of vertical tillage — something like a straight chisel plow — and you are not completely disturbing the soil ... you are retaining some of that risk,”
Cruse also noted the crop grown over the summer may affect erosion. Corn will produce more biomass than soybeans, meaning there is more residue on the fields to limit erosion. Cruse said improvements in soybean genetics are starting to produce more biomass, which is important moving forward.
“Elevated yields have produced elevated biomass,” Cruse said. “The more residue you have in the field, preferentially on the soil surface, the greater interception you have of raindrops and the less erosion you are going to have.”