Using On-farm and On-station Research for Effective Education - Soybean Populations.

County/District Extension agents often conduct demonstrations that include the same treatments being examined by on-station researchers. On-farm plots serve as effective demonstrations of the principles documented in on-station studies. However, results from on-farm demonstrations seldom are utilized beyond the borders of that county or district. Our goal was to use a series of on-farm and on-station studies examining soybean plant populations to enhance the breadth of information collected and its educational value.

 

During 2006 and 2007, county agents, Extension specialists, and researchers from K-State conducted 26 experiments examining soybean seeding rates. Five experiments were located on research stations and 21 were on producers’ fields. Some on-farm experiments were replicated and some were not. The studies encompassed a wide range of production practices, environmental conditions, and productivity. Average test yields ranged from 12 to 78 bushels per acre. Yields from all studies were standardized to percent of the test average to facilitate fitting response curves. Results were summarized by yield level to determine if the optimal population changed depending on yield potential.

 

Yields tended to increase in response to increasing population up to a point. In low-yield environments, yields reached a plateau at a population of about 75,000 plants per acre. In environments with average or greater yields, a population of 110,000 plants per acre was sufficient to maximize yield. At seeding rates less than 150,000 seeds per acre, field emergence ranged from less than 50% to near 100%, averaging close to 80%. When more than 150,000 seeds per acre were planted, emergence averaged 75%.

 

The results reinforced current recommendations and confirmed their validity for additional areas of the state and production systems. Active participation of county agents, area specialists, and producers enhanced the credibility of the results and served as a springboard for dissemination of recommendations.