Beans on Beans (part 1) by Kelley Schroeyers

This year we had a late harvest in Southern Ontario and many growers were unable to plant their winter wheat.

With this in mind, as well as strong market pricing on Soy Beans, many of our growers will be planting “Beans on Beans”.

If you’re one of these growers, you’ll find the following report useful.

                Tech report for Beechwood Agri-services

“Beans on Beans”

In the quest to grow the best possible crop of soybeans, growers appreciate and understand the importance crop rotations.   Years of on-farm trials, cropping experiences as well as a wealth of research data confirms that crop rotations are extremely beneficial for increasing crop yields, adding more bio-diversity, improving soil health and creating better integrated crop pest and disease control and management systems.  But as we know, the best cropping plan may not always be possible.  That’s working with Mother Nature, that’s farming and it is always wise to have a plan B.

That brings up the topic of “Beans on Beans”.  Certainly not a common, nor a recommended practice but more frequent than one would first think.  Higher acreages of 2^nd year soybeans usually coincide with heavy winter wheat kill. This can generate situations where 5% of the total soybean acres are replanted to “Beans on Beans” with only a short break crop of winter wheat during the fall and winter months.  Market conditions may also create unique profitability driven decisions where producers decide to plant “Beans on Beans”.  Growing continuous soybeans is definitely not a recommended practice and creates a situation where it is difficult to maintain longterm yields above profitability levels.  This report will examine the practice of short-term “2^nd year - Beans on Beans” only.

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.

Beans on Beans (part 3) by Kelley Schroeyers

  Recommended cultural practices with 2^nd year soys:

A) Conduct primary fall tillage to bury residue

B) Grow different soybean variety

C) Select variety with excellent disease package, (PPR, Pod & Stem Blight, WM, SDS, BSR, Septoria)

D) Select variety with strong pest protection including SCN and soybean aphid

E) Plant Crusier Maax treated, certified seed

F) Spray with fungicide such as Quilt at R1-R2, consider second spray at R5

G) Scout field for insect and diseases more frequently than 1^st year soybeans fields

By following these guidelines, growers can still produce a profitable crop of 2^nd year soybeans.  It is wise to remember, that many soybean pests are called slow builders.  This is where the pressure slowly ramps up each year, especially in fields where the soybean rotation frequency is higher than desired within the cropping cycles, until the pest pressure reaches critical threshold levels.  Once these levels are surpassed, there is a negative impact on production each time soybeans are grown within the cropping system.  It is said by many soybean specialists including Don McClure, soybean breeder with Syngenta, that soybean diseases and pest are the biggest limiting factor to increasing on-farm average yields.  The guidelines in this tech report are meant to help producers through plan B situations only.  To maintain the highest production levels possible, it is imperative that producers maximize crop rotations with their cropping systems.

Eric Richter, B. Sc (AGR),  C.C.A.

Agronomic Sales Rep

Syngenta Canada