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Achieving Maximum Yield Potential

Principle Investigator: Dr. Larry C. Purcell

Stated Goal: 
To obtain a better understanding of how a high yield of soybeans are obtained in a consistent manner by monitoring  producer Kip Cullers’ farms in Southwest Missouri who has reported yields of 139 (2006), 155 (2007), and 161 bushel/acre (2010). These yields are substantially greater than any other reported maximum yields.

To implement some of the production practices used on the Cullers’ farm and to identify limitations to high yields that Arkansas producers may be facing.

Specific objectives and 2013 Results (summarized): 
Characterize environmental conditions and crop growth at Kip Cullers’ record yielding production field. Plant samples (including those from a non-nodulating variety that was established within this field), were taken periodically during the summer. Data obtained from these samples indicated that biomass and N (nitrogen) accumulation rates ranged from 45.6 to 64.3 g m-2 d-1 and 1.43 to 2.08 g N m-2 d-1, respectively, which are the highest ever recorded. Radiation use efficiency measurements were also higher than all previous reports, ranging from 1.5 to 1.9 g MJ-1. The high nitrogen accumulation rates are important for high-yielding soybean because of the high protein concentration of soybean grain; for example a 100 Bu/ac yield contains about 380 pounds of nitrogen in the grain. Radiation use efficiency is a long-measure of photosynthesis, and the high values from Mr. Cullers’ field are higher than any reports for soybean and near the highest values reported for corn or sugar cane. Replicated yield estimates from Mr. Cullers’ contest field ranged from 92 to 118 Bu/ac in 2013.

 Evaluate specific management practices and inputs that are used on the Cullers’ farm to determine their effectiveness in defined experimental conditions in Fayetteville. One field experiment at Fayetteville evaluated 14 varieties from Pioneer, Monsanto, and Syngenta for yield and growth characteristics in a maximum yield environment. A second experiment evaluated individual management treatments including: thinned evenly & thinned to even emergence, Cobra, Cobra+crop oil, Cobra+crop oil Aim, and Cadet herbicide applied at V3, a 3x rate of Optimize® 400, Accolade-(P)®, and Bio-Forge® seed applied together vs. alone vs. none, 1 or 2 applications of 1-MCP ethylene inhibitor, and prevented lodging. Replicated yields of the variety trial ranged from 74 to 116 Bu/ac and all physiological measurements were similar to the measurements from Mr. Cullers’ contest field. No individual management practices significantly increased yield over the control and yields were very good,  ranging from 72 to 129 Bu/ac.

Demonstrate at University Experiment Stations the effects of intensive, high-management strategies on soybean performance and yield relative to recommended soybean production practices. Demonstration blocks (2ac+) were established on UA Division of Ag Research Stations at Rohwer, Pine Tree, Newport, and Marianna and included recommended production practices and enhanced management practices. Enhanced management included addition of chicken litter (2-3 tons/ac) prior to planting, lower tolerance for insect control treatments, decreased soil-moisture deficit for triggering irrigation, and preventative fungicide treatment at R2 and R5. Yield data have been collected and data are currently being analyzed but 2013 soybean grain yields exceeded 2011 and 2012 at most locations (at some locations exceeding 70 Bu/A).

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