How have soybeans changed over the past century, and what can growers learn from this evolution?
Purdue University agronomy professor Shaun Casteel has some answers. Speaking at the recent Ontario Certified Crop Advisor annual conference, Casteel shared insights from his research comparing varieties from 1923 to those available in 2011.
In this episode of Real Agriculture Soybean School, Casteel discusses the significant changes in newer varieties, including a much higher N removal rate and higher N allocation in plant leaves. He also notes how the bulk of N and P uptake happens after the R6 stage. Typically, most soybean management is wrapped up by the R3 to R4 stage, but with so much happening in the later stages, Casteel believes growers need to consider how they can better manage their crops later in the season.
To make better late-season management decisions, however, researchers need a better understanding of soybean nutrient requirements, says Casteel. He notes that most of the base soybean fertility work scientists and agronomists rely on was done in the 1970s.
He believes a stronger understanding of soybean fertility will allow growers to build programs that target 50 or 70 bushels per acre based on a better understanding of nutrient removal rates and individual field soil fertility levels. He also feels growers have to change their mindset when it comes to managing the crop. Traditionally, soybeans have been expected to prosper based on the scraps left over from the corn crop. That has to change, says Casteel.
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