Beans on Beans (part 2) by Kelley Schroeyers

One important consideration is whether the crop needs to be an identity preserved, non-GMO crop.  This production system will restrict or eliminate some options and will dictate other decisions.  For example, if the first year soybean crop was a GMO crop, it will not be possible to grow a 2^nd year non-GMO, I.P. crop.  The chance of volunteer plants from the previous RR soybean year’s crop is extremely low, but still possible.  Thus, a 2^nd year crop of I.P. non-GMO is prohibited due to the terms and conditions of most production contracts.  In the situation where the 1^st year soybeans were a I.P., non-GMO field, and the grower no plans to re-crop to a non-GMO, identity preserved soybean variety, it is best to plant the 2^nd year crop to the same variety.  With 2^nd year crush beans of course this discussion of non-GMO vs GMO is a non-issue.

From an agronomic perspective there are a number of cultural practices that will help to minimize the yield decline from the dreaded “Bean on Beans” syndrome.  In most years, it is not uncommon to experience a 10% drop in yields primarily from increased disease and insect pressure.  The only exception is when soybeans are re-cropped after 1^st year soybeans on virgin ground.  In this situation, soybean yields may actually increase slightly in the 2^nd year due to the higher population of rhizobia and resulting higher nodulation numbers and subsequent increased nitrogen production for the soybean plant.  The acres on which this might occur in southern Ontario are now extremely rare.