Four Steps to Better Bean Yields

"We use to see 40 bushel beans in the 1940's when we first started growing soybeans and last year I was still growing 40 bushels beans" was a question from the hallway last Friday with a couple area farmers. Their question has been on my mind. I do not have all the answers but a few things that could lead to better bean yields if the proper attention has not been given to these areas. I assume the first question of are we picking high yielding genetics has already been answered and is the starting point.

1. What soil borne problems do you have? Probably the two biggest things we need to consider is phytohpthora root rot, pythium and soybean cyst nematode. If we are not accounting for the presence of these diseases in our production we are losing yield. Phytothora needs to be looked at in a total management way with use of genetic resistance, variety tolerance and seed treatments in a total package to control this critical disease. Pythium likewise needs to be controlled with seed treatment and the treatments are similar to phythothora. An detailed article for more reference Soybeans :When to use a seed treatment and which seed treatment to use? was in a recent CORN Newsletter article. The other consideration from a soil standpoint is soybean cyst nematode. This is a silent yield robber resulting in stunted plants that could be from any number of other things. If you have have not checked field for this problem it can make a significant difference. More information can be found in SCN Factsheet.
2. Soil Compaction is another concern. Soybeans have a tap root and compaction layers can substantially alter the root system. Last summer I watched a field that had a compacted area that seemed to be behind all year long. The root system went down about 4 inches and made a 90 degree turn. The plants got growth to them late season and it would have been easy to just write it off as just wet area but the yield was substantially lower.
3. If you are letting weeds get more than 6 inches tall before controlling them in May and June you are losing yield. Post emergence applications should be planned to assure these first weed flushes do not get ahead of the crop. By 9 inches tall you have lost 6% or 3.6 bushels on 60 bushel beans or at 12 inches 10% or 6 bushels. A good article on weed competition and yield loss in beans is Benefits of Pre Herbicides in Roundup Ready Management Systems.
4. Don’t forget the inoculant! For a number of years, Dr. Jim Beuerlein has evaluated these and they have provided a return on investment. If you are applying inoculant at the same time as the seed treatment be sure that it is a safe combination. 2007 data from these studies can be found at http://agcrops.osu.edu/soybean/documents/12007INOCFINALREPORT.pdf