In the early 20th century, plant nutrition was dominated by the soil chemistry paradigm of nitrogen, phosphorus, and potassium. Micronutrients were largely ignored and poorly understood, partly because existing methods did not allow precise adjustment of micronutrient levels in plant growth media. The importance of most of today's known essential micronutrients, including boron (B), was largely overlooked, even though abnormal crop growth on certain soils could be “rescued” by adding B.
