Summary

In the Aug. 2012 issue of “Corn & Soybean Digest”, there is a multi-page insert titled “Extreme Beans–New High Yield Research” that describes the conduct and results from a 2009–2011 project dubbed “The Kitchen Sink Project” that was funded by the USB. The purpose of this project, which was conducted at three locations each in Arkansas, Iowa, Kentucky, Louisiana, Michigan, and Minnesota (for a total of 18 sites), was to determine inputs that could be recommended for the production of higher-yielding, higher quality US soybeans.

Description of Study

The study employed an “omission treatment structure” to test the impact of five inputs, which were:

●          Seed inoculant (SI–Vault),

●          Seed treatment (ST–Trilex 6000 or CruiserMaxx),

●          Additional soil fertility (ASF),

●          Foliar fertilizer (FFERT–Task Force 2), and

●          Foliar fungicides (FFUNG–Headline and Quilt).

The omission treatments included all of the above five inputs minus one. The ASF treatment involved adding Phosphorus, Potassium, Sulfur, Boron, and Manganese to soils that were already at the high or very high level of fertility for the standard nutrients as determined by soil testing labs in each respective state.

There were also

●          Early-season (SI, ST, and ASF) and late-season (FFERT and FFUNG) treatments, and

●          Control systems that included a wide-row (30-in.-wide rows) and a narrow-row (20-in.-wide rows or narrower) system that received either all or none of the above additional inputs.

Varieties/maturity group were selected by participants at each location. Planting date and tillage environment, which ranged from no-till to conventional tillage, were also selected by the scientists at each study site to match local preference.

The objective of this large-scale study was to gain knowledge about what is going to happen when these inputs are applied over a wide range of environments, and to determine if they can contribute to achieving a higher soybean yield plateau.

Take-Home Message

Preplant Fertilizer. These studies were conducted on sites that either had or were fertilized to bring soil nutrient status to recommended levels before the project was initiated. So, they do not provide information about the economic gain or loss from producing a soybean crop on under-fertilized soils vs. those that are fertilized to reach recommended levels according to soil test results.

Thus, the tried and true adage that soybean yields will be maximized by having the recommended levels of nutrients held true in this 3-year study. Conversely, over-fertilizing beyond levels that are recommended in an attempt to obtain higher yields loses money.

In essence, the results from this portion of the study confirm the importance of following soil test recommendations to provide the proper levels of required nutrients for a productive soybean crop.

Seed Treatments. The results from this portion of the project confirm that using soybean inoculants and seed treatments is not likely to result in heretofore unseen soybean yield increases. Rather, inoculants should be considered for use as cheap insurance where native populations of N-fixing bacteria are lacking, and seed fungicide/insecticide treatments should be used as stand enhancers and as insurance against costly stand failures in the Midsouth. Check out the White Paper on the MSSOY website for a guide to using both of these inputs.

Foliar Fertilizer. Results confirm that application of foliar fertilizer to soybeans late in the season has not and still does not appear to be a viable input for increasing yields in a high-yield environment.

In a blog posted on the MSSOY website, the case is made for applying small amounts of N fertilizer to soybeans at the mid-reproductive stage (R3) when grown in high-yield environments with low residual soil N. Response to this soil-applied N late in the season is not predictable, but it is one possible late-season fertility input that should be considered for Midsouth soybeans that are grown in high-yield environments. Foliar-applied N does not appear to offer the same benefit.

Foliar Fungicides. Foliar fungicides should be an input component for soybeans growing in a high-yield environment when diseases are present at yield-limiting levels. The small yield and/or economic gain realized from their use when only low levels of diseases are present will hasten resistance development in fungal organisms. The long-term negative effect from this latter occurrence far outweighs any small short-term gains realized from their annual use.

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.

Final Assessment

Over the entire 3 years of the study conducted at 3 sites in each of 6 states, the high-input treatment (received all 5 of the inputs) yielded an average 6.9 and ~4 bu/acre more than the control treatments (received none of the 5 high-input treatments) planted in 30-in.-wide rows and 20-in.-wide or narrower rows, respectively.

With the increased cost associated with applying the 5 treatments to the high-yield wide- and narrow-row environments, it is not surprising that net returns from the high-yield environments in both row spacings were greatly below those from the control treatments in both row spacings.

The only one of the 5 high-input treatments that showed promise for increasing yields and net returns in this study was the late-season application of foliar fungicides. This finding has important implications for Midsouth growers who are more likely to have disease infestations that are above thresholds.

The most impactful result from this study was the confirmation that row spacing is a key component for the production of high soybean yields. In both the control and high-input treatments, narrow rows outyielded wide rows and resulted in higher net returns. Put another way, the narrow-row system with no high-yield inputs yielded as much as the wide-row system with all 5 inputs, and thus provided higher net returns. Again, this is probably the most important finding of the study.

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The results reported in this article indicate three things.

●          Currently available inputs applied to soybeans are best used at currently 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; and

●          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.

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I recently contacted Dr. Seth Naeve, the Principal Investigator for this project. He conveyed to me that more intensively analyzed results with be forthcoming for:

●          Plant stand data;

●          More complete economic models;

●          Light interception and yield; and

●          Seed quality data.

I will stay abreast of these soon-to-be-published results, and report them on this website.

Also, the study has been renewed for 2012-2014. Four states (WI, IL, IN, and KS) were added, while LA will no longer be part of the study.

Composed by Larry G. Heatherly, Oct. 2012, larryheatherly@bellsouth.net