Addition By Subtraction

Three yield-limiting factors and how to eliminate them

As farmers strive to maximize soybean yield, one university researcher found three factors that regularly contribute to lower productivity.

“With recent fluctuation in the price of soybean grain, many farmers are interested in what they can add to soybeans to increase yields,” said Laura Lindsey Ph.D., assistant professor at The Ohio State University, on a recent Focus on Soybean webcast, Limitations of Soybean Yield.

However, instead of focusing only on increasing yield, Lindsey says farmers should also think about ways to eliminate factors that decrease yield.  Based on two years of research on 149 farms in Ohio, Lindsey identified three such barriers:

• Planting date –Early planting – for example, before May 16 in Ohio – can result in, on average, five bushels more per acre.
• Action: Plant as early as conditions allow. This generally means the soil temperature is at least 50 degrees and the soil is not too wet, as the threat of diseases increases in cool, wet conditions. Consider using a seed treatment to help prevent soybean diseases.
• Soybean cyst nematode (SCN) – These small parasites attack the root of a soybean plant and are the number one yield robber each year. Controlling and preventing the increase of SCN in fields can lead to higher yields. Fields with less than 200 SCN eggs per 100 cubic centimeters of soil yielded three bushels more per acre in Lindsey’s study.
• Action: Be sure to test your soil after every third soybean crop, or every six years in a corn-soybean rotation, to check the level of SCN. Test your soils more frequently if previous soil test results show high levels of SCN. In addition to testing, rotation with a non-host crop is the next best management practice.
• Optimum nutrient levels – Phosphorus (P) and potassium (K) are two critical nutrients for soybean production. Lindsey says fields with P levels greater than 15 parts per million produced seven bushels more per acre. Successful K levels will vary from field to field.
• Action: Test the nutrient levels in your soil and apply P and K based on the results in order to maximize your profitability from those fields.