A Furtherance of USB's Kitchen Sink Project

Soybean growers are continually searching for inputs other than variety that will increase yield when applied to given situations and under given economic conditions.

According to NASS, soybean price during the 2008-2014 period was in the $10 to $14/bu range, with a low of $10/bu in 2011 and a high of $14/bu in 2012 and 2013. Thus, income from soybean production during this period was significantly greater than in prior years. Since the above cited period of high commodity prices, soybean price has taken a significant downward turn to $9.50/bu in 2015 and about $8.50/bu in Feb. 2016.

A logical offshoot from the relatively high commodity prices in the above period was the interest among producers and researchers in determining if maximizing inputs to soybean would result in high yields coupled with high returns. That is, would high commodity prices allow the application of prophylactic applications of inputs vs. the traditional management system which calls for the application of only those inputs that are warranted from site history or integrated pest management (IPM) recommendations that are based on insect treatment thresholds and disease infestations that are known to reduce yield?

In previous blogs on this website, I reported results from USB’s Kitchen Sink Project that was conducted in 2009-2011 to determine if higher commodity prices warranted adding inputs for soybean production that were beyond those recommended as standard production practices by University Extension. Links to and a brief summary of those blogs follows.

Part I–Introduction. Description of study and objectives.

Part II–Preplant Fertilizer. Soybean yields will be maximized by having the recommended levels of soil nutrients, and over-fertilizing beyond those levels loses money.

Part III–Seed Treatments. Using soybean inoculants and fungicide seed treatments is not likely to result in yield increases. Rather, inoculants should be considered for use as cheap insurance where native populations are likely lacking, and seed-applied fungicides should be used as insurance against costly stand failures.

Part IV–Foliar Fertilization. Application of foliar fertilizer to soybeans late in the season is not a viable input for increasing yields in a high-yield environment.

Part V–Foliar Fungicide. Foliar fungicides should be applied to soybeans in a high-yield environment when diseases are present at yield-limiting levels. Using these products on a regular basis as a “yield enhancer” is not economically feasible, and will hasten resistance development in fungal pathogens.

Part VI–Summary. Applying all of the above inputs to soybean in a “high-yield” environment resulted in significantly lower net returns. The only treatment that showed promise for increasing yield and net returns was the late-season application of foliar fungicides. Row spacing was the key component for high soybean yields; i.e., narrow rows outyielded wide rows and resulted in higher net returns even with none of the above high-yield inputs. These results indicated the following.

●  Currently available inputs applied to soybean are best used at current recommended levels and only when the best information available indicates they are needed.

●  Future dramatic increases in soybean yields will have to come from genetic improvements in such traits as pest resistance and stress tolerance.

●  Improvement in economic yield, or maintaining current yield levels while cutting costs to produce that yield, may be the needed research direction in the short-term.

The above USB-supported research was continued in 2012-2014. Results from those years of the project are reported in two recent Crop Science articles, one by David A. Marburger et al. and the other by John M. Orlowski et al. (posted by Crop Science on Apr. 13, 2016).

Each report gives results from field trials that were conducted at 19 sites across nine states during the 2012-2014 growing seasons. At least two study locations were established in each state each year. Six high-yielding varieties suitable for each location were chosen by the collaborating university agronomist from each state. These articles are rather long and detailed, so I will provide a summary of pertinent points and conclusions only.

Three input systems were used: 1) current university recommendations for fertilizer and herbicide applications; 2) high-input consisting of No. 1 above plus seed-applied fungicides, nematicides, insecticides, and inoculants, soil-applied N fertilizer, and foliar-applied fertilizers, insecticides, and fungicides; and 3) No. 2 minus foliar-applied fungicides.

Results from the two studies follow.

●  The results overwhelmingly indicate that variety and production system input decisions can remain independent. That is, inputs to varieties that are different should yield the same results. Thus, variety selection remains the most important management decision to be made by soybean producers.

●  High-input systems produced small increases in seed yield in some cases, but breakeven probabilities were 0% at most yield levels and soybean commodity prices.

●  Soybean producers interested in maximizing yield in most environments would be better off to identify specific problems, conditions, or deficiencies, and apply specific inputs that address those issues.

●  Foliar fungicides and insecticides should be an input component for soybeans growing in a high-yield environment only when diseases and/or insects are present at yield-limiting levels. The sometimes small yield and/or economic gain realized from their use when only low levels of these pests are present will hasten resistance development in fungal pathogens and insects. The long-term negative effect from this latter occurrence far outweighs any small short-term gains realized from their annual use as a “plant health” enhancer.

In the Midsouth, foliar diseases frequently are present at yield-limiting levels. Thus, applying foliar fungicides is likely to be a more common practice for Midsouth soybean producers. This will entail using a thorough scouting protocol to ensure that the anticipated yield gain from controlling these diseases is worth the possible hastening of resistance development that may occur from the increased frequency of their application.

Thus, soybean producers should closely monitor pest pressure through scouting and only apply pesticides once pest populations/levels reach threshold or known yield-reducing levels. This practice of IPM will help ensure that both fungicides and insecticides remain effective against pests that reach threatening levels.

●  Seed treatment inputs had low break-even probabilities in this study. However, Midsouth growers are reminded that using a broad-spectrum seed treatment is cheap insurance to avoid replanting a failed stand from an early planting in conditions that are conducive to stand-reducing pathogens, especially since replanting following a failed stand likely will result in a lower yield because of the resulting later planting date.

As stated above, soybean commodity price has taken a significant downward turn to $9.50/bu in 2015 and about $8.50/bu in Feb. 2016. This precipitous drop in soybean price considerably alters the economic landscape for soybean production. That is, even high yields that receive a relatively low price will not necessarily result in profit if input costs are unnecessarily high as a result of applying prophylactic inputs vs. applying only those inputs that are justified by applying IPM methods that verify yield-reducing conditions.

An MSPB-produced video featuring Dr. John Orlowski, Assistant Research/Extension Professor of Agronomy at MSU-DREC, will be posted on this website at a later date. Dr. Orlowski will provide more detail about the above studies in that presentation.

Composed by Larry G. Heatherly, Apr. 2016, larryheatherly@bellsouth.net