By Wayne Flanary, Field Specialist in Agronomy

Growers seek to maximize yields and look for various inputs that will increase yields. Therefore, many products are available for growers to choose from. Research indicates that the weather during the growing season may contribute to twenty percent or more of annual crop yield.

With corn it is critical stage of pollination and two weeks after then impact of weather lessens over time. With soybeans, the plant has three racemes at each reproductive node and each raceme contains five to six flowers. This allows the plant to continue to its reproductive stage and take advantage of conditions for high yields.

The principle of the “most limiting factor” is the one factor that is limiting yield and often shown as a pictorially as a barrel with staves and the shortest stave being the limiting factor. The limiting factor may not be a nutrient. Crop yield limiting factors can be identified through some type of testing or through using on-farm trials to test inputs and measure the input’s impact on yield.

For example, precision soil sampling has allowed us to find areas of the field with yield limiting nutrients such as phosphorus and potassium. Also, we have been able to identify low pH areas of the field and adjusting pH to increase yields.

Another principle is the ability to create synergy to enhance crop yields. An example of this is when fertility is adequate, you also have created an environment which can handle drought better than field that may not have critical levels of fertility.

To specifically measure yields and examine crop inputs, trials at Graves-Chapple Extension and Education Center have focused five years of looking at different crop inputs and resulted in identifying the yield contribution of various inputs. We looked at fertilizer rates, population, fungicides and so forth. We tested seven different inputs for corn and for soybean. The resulting data will be published in the annual report from the center this winter and will be presented in winter ag update meetings.

Also, to identify what may be limiting factors in your crops, watch for the annual soil fertility course which is which is multiple night meetings scheduled in January and February. This year, this course will be held at Savannah. This is an in-depth course to help you work with your supplier to maximize your fertilizer application efforts.

For more information, contact Wayne Flanary, Field Specialist in Agronomy, University of Missouri Extension at 816-279-1691 in the Buchanan County Extension office or directly at 913-220-3670.