Boron can become less available to plants when there is too much nitrogen. Boron (B) is classified as an essential micronutrient because it is used in relatively small quantities in plants and is necessary for plants to complete their life cycle. Research has shown that three commonly used soil tests, the Mehlich-1 and -3 tests and the DTPA test modified to include sorbitol, also may be used to determine available boron in soils. Also know that since boron is leachable it does cause toxic levels in ground water/well water but really the only thing you can do is leach it out if you want to save you plants. Depending upon how much boron you added, the problems you see may have other causes. One of the first things I learned in … Boron was one focus of the Ultimate Canola Challenge in 2015. Also, which plants "struggling" and what do you see?

Institutionalized patients may receive only 0.25 mg of daily boron.

Boron is quite soluble and readily leached in some soil types, especially sandy soils typically used for vegetable production. Organic matter ‑ organic matter provides boron as it breaks down and also improves the ability of soil to hold boron. Chemical fertilizers inhibit the uptake of boron from the soil: an organic apple grown in good soil may have 20 mg boron, but if grown with fertilizer it may have only 1 mg of boron. So even though boron only registers 0.5 ppm to 2.0 ppm on most soil tests, you don’t want plants to run short.

Boron is the “gate keeper” for calcium uptake. Boron can become less available to plants when there is too much nitrogen. Soil testing and plant analyses are both helpful in assessing the potential boron-supplying capacity of the soil and the current boron status of the plant.

As you can see, Iron, Zinc and Boron all do important things for the soil. A 1999 study by Rigas Karamanos showed no relation between HW boron levels and canola yield. So in South Australia, for example, in our grain growing regions, we think about 30% of our soils have levels of boron above about 15 mg/kg in the top 100 cm soil, just generally consider the threshold for Boron deficiency results in short, thick cell walls, and root and pollen tube elongation is inhibited. Source: University of Minnesota Boron can become less available to plants when there is too much nitrogen. Wear protective clothing, including safety eyewear, and wash well with soap and water after applying the boron. What are the best soil amendments? A 1999 study by Rigas Karamanos showed no relation between HW boron levels and canola yield.