| Concept Research Field Tests Input Options
Real life scenerios provide return-on-investment answers
By: John Oolman Concept research takes up where small plot research leaves off - incorporating field-size variability. Today's growers want hard proof that a product, service, or management option has been tested under field conditions similar to their own. They can't apply standardized small plot research data conducted under ideal controlled growing conditions to large fields without weather, pest and soil variability.
Filling this information void is the goal of John Oolman, director of Concept Research at Agri-Growth, Inc. in Hollandale, MN. Agri-Growth conducts replicated studies under real field conditions on more than 1500 acres in southern Minnesota plus across the major corn, soybean, and wheat growing areas of the Midwest and High Plains. "The studies are laid out side-by-side under field conditions in plots of 20 to 80 acres with precision ag technology. Harvest data is overlaid on maps for soil type, topography, organic matter, phosphorus, and potassium and analyzed through geostatistical GIS and spatial analysis," said Oolman. "The results are calculated into return on investment, the grower's bottom line. These are the types of things a grower can do on his own farm to test products and practices."
GIS technology layers the maps while graphs, tables, geostatistical, and statistical analysis interpret the data. GIS and GPS combined help move growers from plotting and describing areas in their fields to prescribing a product or management process. Modern GIS pushes beyond data mapping, management, and modeling to the spatial reasoning and processing techniques of this technology. Case Study of Herbicide Affect on Yield
This Concept Research case looks at the effect of herbicide application on yield, a topic most herbicide companies don't address directly. The study looks at a corn/soybean rotation with five corn herbicides applied side-by-side in 20 foot wide strips and three soybean herbicides applied side-by-side in 100 foot wide strips on two adjacent 24 acre fields. What makes a study of this type so important? "Each input makes an impact on yield and managing that input for its maximum potential brings the value to precision ag technology and the grower," stressed Dr. James Ladlie, president of Agri-Growth. "The key to increasing yield is in understanding how to reduce crop stress."
The study looks at the effect of herbicide "mode of action" on yield through two years. The five corn herbicides and three soybean herbicides were applied to the same field over a corn/soybean crop rotation. Three classes of products were evaluated: metabolic inhibitors; growth regulators; and photosynthetic inhibitors. The mode of action combinations over the two year period compared the same mode of action "stacked" each year or in combination, i.e., metabolic inhibitors followed by growth regulators; growth regulators followed by photosynthetic inhibitors; metabolic inhibitors followed by photosynthetic inhibitors,etc.
Herbicides used in the study represent the most widely used herbicides sold today in corn and soybeans. All herbicides were applied at the recommended rate and time of application based on label guidelines.
In the study, 1997 corn acreage was rotated to soybeans in 1998 and the 1997 soybean acreage was rotated to corn in 1998. The plot diagrams (see sidebar) show five corn herbicides each applied in a strip 20 ft. wide and three soybean herbicides each applied in a strip 100 ft. wide. This allows the five - 20 ft. wide strips to cover one soybean 100 ft. wide strip. With precision ag equipment this allows Concept Research to compare the effect of all five corn herbicides against each soybean herbicide in side-by-side field conditions. Each treatment is replicated several times. Yield maps and plots for 1997 are similar to 1998.
In the study, herbicides are lettered "A" through "H" with each letter representing a different herbicide. The 1997 yield results in corn and soybeans show that herbicides with different modes of action caused yield differences for both crops. Yield results ranged from soybeans treated with herbicide "C" at 45.1 bu/A to soybeans treated with herbicide "B" at 48.2 bu/A to soybeans treated with herbicide "A" at 51.7 bu/A in 1997. A similar trend is present in the corn results for herbicides "D" through "H."
The 1998 yield results in corn and soybeans show each herbicide's mode of action caused yield differences for both crops. Yield results ranged from soybeans treated with herbicide "C" at 47.5 bu/A to soybeans treated with herbicide "B" at 49.6 bu/A to soybeans treated with herbicide "A" at 52.8 bu/A in 1998. Again, a similar result was evident in corn. The Bottom Line
Agri-Growth's two year study of herbicide "stacking" interaction and its affect on yield under actual field conditions and crop rotation points out the effect herbicide mode of action can play on yield. In an instance where a similar mode of action was used back-to-back in following years, lower crop yields were the result. Using differ ent herbicides with similar modes of action has the same result as using the same herbicide year after year - yield loss. The use of dissimilar modes of action reduces the chance of similar herbicide "stacking" and carryover and removes another chance for crop stress and yield loss.
Yield loss related to herbicide mode of action is one area that is easy to remedy. Alternating herbicide mode of action can mean up $40/A difference in corn yield at $2/bu. and $52/A difference in soybean yield at $5/bu. over the two years of the study. Put another way, using the same herbicide mode of action year after year can cost the operation a loss per corn acre of $40/A over two years. Soybean's loss per acre due to "stacking" herbicide mode of action comes in at $52/A over two years in this Concept Research Sequential Herbicide Study. About the Author:
John Oolman is director of Precision Farming and Concept Research at Agri-Growth, Inc., in Hollandale, MN. Agri-Growth conducts Concept Research trials and offers training in precision agriculture. Back |
