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2015 Craven County Soybean Yield Enhancement Trials

N.C. Cooperative Extension often provides on-farm trials evaluating products used in production. This is especially critical when testimony promotes the use of a product yet no replicated research trials are available to support or refute the claim. As example, in 2014, several growers and dealers cited a favorable yield increase to foliar application of manganese (Mn) to soybean while others cited yield increases from the application of Mn combined with a fungicide. Some advanced the philosophy that added in-furrow products added yield. When needed, Mn shows very favorable yield increases but no data is available to promote application of this fertilizer as a yield enhancement product. Likewise, NCSU data presented by Dr. Jim Dunphy, Professor of Crop Science and Soybean Extension Specialist, shows varying degree of yield increases from these other products. However, on average, the yield increase is small and variable depending upon climatic and realistic yield expectations of of the site.

To evaluate some of these products and claims, replicated trials or side-by-side comparisons were established within Craven County in 2015. Specifically evaluations included the use of Mn, the fungicide Quadris™, starter fertilizer application and potential yield enhancement products. Funding was provided by donations from Crop Production Services of Vanceboro, NC;  Cove City Fertilizer, a L. Harvey & Son service center in Cove City; and, the North Carolina Soybean Producers Association. Too, and most importantly, individual growers provided the use of land, equipment and time to establish and harvest these plots. All fields followed fertilization recommendation provided by the North Carolina Department of Agriculture & Consumer Services Agronomic Division.

Foliar Manganese (Mn) and Fungicide Trial

This test site (three replications of each treatment) compared a foliar application of Mn at 0.5 lb/ac of actual Mn per acre, foliar Mn at 0.5 lb/ac actual Mn combined with Quadris™ at 6.0 oz/ac, and Quadris™ at 6.0 oz/acre alone to an untreated check. Applications were made using grower equipment when the soybeans were at the 4th trifoliate stage on June 30th. Plot width was 90 feet wide but length varied slightly to fit the field’s irregular shape. Each replicated strip plot was harvested using grower equipment and data recorded from a yield monitor. Harvest occurred on November 17th. Moisture content of the plot at harvest was 10%.

Two sets of data are provided. Regrettably, yield monitoring equipment malfunctioned within harvest of the last three plots. Thus, the red bars on the graph show the simple average of the first two replications only. This eliminates any potential error due to incorrect information gathered from the yield monitor on the third replication. The blue bars on the graph represent an attempt to recover reasonable data by reducing the erroneous yield monitoring data for only the last three plots. Realize, this (dat with blue bars) is an assumption based upon observation and reasonable estimation based on previous harvest data.

2015 Foliar Yield Enhancement Trial, Craven County NC

2015 Foliar Yield Enhancement Trial, Craven County NC

Due to the error in gathering data and very small differences in yield, it did not seem feasible to analyze the data using statistical analysis. Rather a cost of return evaluation is used using the simple arithmetic average (red bars).

Assuming a cost of $6/ac for the fungicide, an application cost of $6 per and a soybean price of $8.50/bu, then the breakeven yield for the most expensive treatment is about 1.5 bu/ac increase in yield. The data collected from this trial does not show a 1.5 bu/ac increase in yield above the untreated check for any treatment. Thus, application of any product or combination of products in this trial resulted in reduction of profit.

Side by Side Yield Enhancement Comparison

This side-by side trial examined treatments of Black Label™ combined with Accomplish™ and Radiate™ to AgriPop™ with a chelated micronutrient product applied in-furrow to an untreated check plot. Each treatment was approximately 4.5 acres and was planted using grower equipment in early June. Harvest occurred on November 27, 2015. Moisture content was approximately 18% at harvest and harvest followed several weeks of rainfall. Thus, damaged soybeans were common.

Data shows a decrease in yield within all plots with yield enhancement treatments. A reasonable explanation for this decline might be salt injury to small seedlings during early season growth. Within 10 days of planting, temperature exceeded 90 degrees F and no rainfall occurred until mid-July. It is possible that slower growth and less root development occurred due to excess salt from fertilizer and products applied in furrow.

2015 Soybean In-Furrow Yield Enhancement Evalaution

2015 Soybean In-Furrow Yield Enhancement Evaluation

In fairness to those representing these products, the weather and soil conditions shortly after planting were unusually hot and dry. Salt injury might have occurred regardless of product. Too, this was not a replicated trial. Thus, slight changes in soil type may have influenced data. Lastly, as always, extreme care is advised any time only one year of data is presented. Such limited data only shows response of products evaluated for one set of climatic conditions, planting date, variety, etc. Thus, we hope to evaluate these products again in 2016.

Soybean Starter Fertilizer Trial

This replicated trial (three replications of each plot treatment) compared a soybean starter fertilizer supplying 20 lbs/ac of actual nitrogen with and without 0.5 lbs/ac actual Mn to an untreated check plot. This plot was planted on 20 inch rows planted in early June. Excessive and continuous rainfall delayed machine harvest. Thus data was estimated using the size and number of pods on 1/10000th of an acre as described in the Purdue Extension publication, Estimating Soybean Yields-Simplified. Eight sample areas were randomly selected from each replicated treatment area (24 total for each treatment).

Statistical analysis shows no difference in treatments. Average yield for all treatments is 49 bu/ac. Average soybean yield with a starter alone is 48 bu/ac, average of soybean yield with a starter with Mn is 51 bu/ac and average of soybean with no starter is 49 bu/ac.

2015 Soybean Starter Trial, Craven County, NC

2015 Soybean Starter Trial, Craven County, NC

Quadris is a registered Trademark of a fungicide manufactured by Syngenta

Black Label, Accomplish and Radiate are Trademarks of Loveland Products

AgriPop is a Trademark of L. Harvey & Son Company


None of these trials demonstrated added value from potential yield enhancement products.

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