Grower Resource: The Relative Importance of P and K for Soybean

BY Carrie Laboski | February 23, 2016 - 

In two simple, clear videos that take less than a half hour to view, I show you the relative importance of P and K for soybean.

In the first video, shot back in 2011, you’ll see for yourself how application of P and K affect soybean in low nutrient soil under controlled conditions. You’ll also how see how potassium is a major driver in increasing yield.

I also consider how other important crop management factors, such as no till farming and harvesting straw can have on potassium access and levels in your fields.

In the second video, just published in February, 2016,  I have even more data under my belt. Again, potassium delivers the biggest bang for the buck. The effect is obvious, even in a drought year.

Another interesting point raised by the research so far is the insignificant effect of phosphorus on yield. In data obtained from test fields in Arlington, there was no yield response to phosphorus even though initial soil test P levels were less than less than 8ppm.

My study—funded in part through check off dollars—continues and will undoubtedly lead to an even greater understanding of how to use nutrients wisely. In the meantime, my study builds a compelling case for thorough soil testing for potassium and smart use of potash to increase yield.

Relative importance of P and K
Even at very low levels of tested potassium, you can see the clear difference.

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Carrie Laboski