Will fallow syndrome affect your acres in 2020?
Did you have prevent plant acres in 2019? In Iowa alone, there were more than 460,000 prevented plant acres last year. One concern that stems from unplanted fields is fallow syndrome. Fallow syndrome occurs when populations of good fungi, or vesicular-arbuscular mycorrhizae (VAM), are reduced due to the lack of actively growing roots. These good fungi help with nutrient cycling and plant nutrient uptake, specifically for phosphorus in corn.1
Any plant roots in a field, whether those from a cover crop or weeds, can reduce the risk of fallow syndrome for the following crop. If you did not fill those acres with a cover crop, fallow syndrome should be a concern this year.
Corn acres are at the greatest risk for yield loss from fallow syndrome, so one suggested solution is to plant soybeans in susceptible fields, according to university research. Iowa State suggests that starter fertilizer is not necessary for soybeans, but if it is used, it should not be placed in-furrow.
If you choose to plant corn on those acres, there is less data to support yield response with fertilizer application. The University of Minnesota Extension recommends banding phosphorus and chelated zinc directly on the seed as starter at planting2. However, specific application rates depend on region and state. Work with your AgVenture Yield Specialist to determine appropriate applications of phosphorus and nitrogen that may help combat yield losses.
Additional questions can be directed to AgVenture agronomy expert Louis Sutton.
1 Iowa State University Extension. https://crops.extension.iastate.edu/blog/rebecca-vittetoe/will-fallow-syndrome-be-issue-2019-prevented-plant-acres
2 University of Minnesota Extension. https://blog-crop-news.extension.umn.edu/2020/04/spring-management-of-prevent-plant-acres.html