Target Boron Levels

Depending on the crop, but for corn, shoot for 20 ppm in the soil. I have talked with many consultants in the past week and 5 ppm should be plenty. Boron can have negative impacts on soil biology when it gets to high. Many soils routinely test less than 5 ppm and in many cases under 1 ppm.

Read the whole article here http://blog.calciumproducts.com/posts/boron-.cfm