Tillage & soybean yields
If you're nervous switching to no-till or minimum tillage for fear you'll lose soybean yields, new data should help calm those nerves.
Especially with today's rising diesel fuel costs, making the switch to a minimum tillage system should net you more profit per acre of soybeans you raise, according to Iowa State University (ISU) Extension agronomist Mahdi Al-Kaisi. Almost a decade's worth of studies conducted at different locations around the state of Iowa in different crop rotations (corn-soybeans, corn-corn-soybeans and continuous corn) show that there's no real correlation between soybean yield and tillage system.
"Nine years of results from long-term tillage and crop rotations studies in Iowa showed that regardless of tillage system or crop rotation, soybean yields are not affected by tillage system. This is encouraging news for producers who are reluctant to switch to no-tillage soybean after corn due to concerns of poor crop performance," Al-Kaisi says in a recent report. "With current increases in diesel fuel prices, some growers could save costs by minimizing tillage passes before planting soybeans."
Though the tillage system doesn't seem to affect yields, the crop rotation does, Al-Kaisi adds. The differences aren't enormous -- ranging from 3 to 6 bushels per acre higher for corn-corn-soybean rotations over corn-soybean rotations -- but are enough to consider when making acreage decisions.
"Tthe trend shows an advantage in soybean yield following 2 consecutive years of corn over one year of corn in the rotation," Al-Kaisi says. "Potential causes for better performance of soybeans after 2 years of corn may be due to reduced risk of some soybean diseases because of a break in disease cycle that may be associated with the corn-soybean rotation as documented in some research. Economic return, input cost and other management considerations must all be taken into account before deciding to change crop rotations."
And, don't forget that other crop in the rotation. Corn can be affected much more by a range of weather conditions, so both crop rotations and tillage systems should take that into account. "Corn yield of continuous corn or corn following soybean is often lower with no-till system compared to conventional tillage, especially in poorly-drained and cold soils," Al-Kaisi says.