Unless you are old enough to remember early TV shows sponsored by 20 MULE TEAM BORAX, there’s a good chance that you have never heard of boron.
As a close cousin to carbon on the Periodic Table of Elements, boron is a very lightweight element that appears worldwide on land and in the oceans in various concentrations. Scientists have not universally agreed whether boron originally comes from the sea and aerosols to land or dissolves from land sources and finds its way to the sea via surface water discharge. It doesn’t exist naturally as the element boron, but rather as solid boric acid (H3BO3) or as borax (Na2[B4O5(OH)4].8H2O). Both forms are readily water-soluble, so boron can also be found in well water supplies because it dissolves in rainwater and percolates through the soil into aquifers. Aquifers in contact with borax mineral deposits as well as those with seawater intrusion will also have elevated boron levels.
Commercial uses for boron compounds range from improving rare earth magnets for electric vehicle batteries to a detergent additive. As a detergent additive, borax (see above formula) actually precipitates the calcium (hardness) and leaves the sodium in the water. This process is similar to physical water treatment non-salt water softeners which are rapidly replacing salt-type water softeners with devices that use zero water and discharge zero pollutants to drain.
Both the medical and the agricultural communities refer to boron as a micronutrient. In this status, some presence of boron is vital to human and animal development as well as plant health. For humans and animals, boron works in concert with vitamin D to assist the assimilation of calcium which is necessary for bone, tooth, and brain tissue growth and maintenance. Its importance is so much so that those with a deficiency of vitamin D, maybe due to a lack of sun exposure, often take vitamin d drops to maintain this balance. Ideally, humans will ingest approximately 1 mg of boron daily through the consumption of green, leafy vegetables, drinking water, and non-citrus fruits. Above 3 milligrams daily some health issues may arise including diarrhea, vomiting, indigestion, and headaches. Fatal doses are in the 15,000 to 20,000 range. Drinking water has the potential of raising the boron intake above healthy levels, thus the USEPA sets a non-mandated limit of 2 (children) to 3 (adults) milligrams per liter; the World Health Organization limit is 2.4 mg/l, and states including California set an upper limit of 1 mg/l.
In plant growth, the effective uptake and use of phosphorus and calcium are assured with only trace amounts of boron available at the roots. This presence follows Liebig’s Law of Minimums meaning that in the absence of boron, plants will not absorb phosphorus or calcium at sufficient levels regardless of how much is applied. Unlike standard human upper tolerance levels, damages to plants begin at in-the-water levels of >0.5 mg/l for blackberries and cannabis to >15 mg/l for asparagus.
If there is insufficient boron present, there are readily available supplements for humans, animals and crops. Excess boron, especially in water, is an entirely different issue. The go-to technology of reverse osmosis simply doesn’t work. The low energy of the boron ion negates ion diffusion upon which osmosis membrane rejection depends upon. Likewise, traditional ion exchange resins fail to remove boron regardless of what regenerant chemical is used. Recently, an adsorption filter medium selective to boron and not interfered by other ions has become available. Devices are available as disposable point-of-use cartridges for point-of-use drinking water applications as well as regenerating small and large pressure vessels for agricultural applications. Typically, a bit pricey, but proven to be effective. The agricultural versions often mean having a viable business or not.
1. WHAT IS BORON?
It is a naturally occurring element with the chemical symbol B. The Periodic Table of the Elements refers to it as element number 5 which is its atomic number or AN. This tells us that there are 5 positively charged protons with an assigned weight of 1 each in the core of a Boron atom surrounded by 5 negatively charged, weightless electrons in orbit around the core. The like number of positively and negatively charged particles cancel one another so the boron atom, as all atoms in the table, have a zero electrical charge. Joining the protons in the core are 6 neutrally charged particles aptly called neutrons. They have an assigned weight of 1 each or 6 total which when added to the 5 of protons gives a total weight of 11 for boron. This is referred to its molecular weight or MW.
Boron is a very sparse element in the earths crust and is found primarily as boric acid {B(OH)3} or borate {B(OH)4-} compounds and never in its elemental form. Once laboratory isolated into elemental form, boron is an extremely hard, black material not totally unlike its chemical cousin carbon with its AW of 6 and MW of 12. Major accumulations of boron mineral compounds are found in Turkey, Russia and Northern California. Boron compounds are very soluble in water so after eons of time, sea water now contains an average of 4.5 mg/l (4-1/2 pounds in 110,000 gallons). As a result of seawater evaporation and intrusion into ground water over the ages, boron can be found in trace amounts virtually everywhere with typical values in water of 0.5 mg/l or less. Higher values are seen in areas with high ground mineral deposits.
2. WHAT IS BORON USED FOR?
- Making high temperature, dimensionally stable glass
- Making extremely strong rare earth magnets
- Making high power density, rechargeable batteries
- Strengthening metal alloys
- Making certain cleaning and bleaching compounds
- As a soil additive for certain crops
- As dietary supplement
3. HOW DOES BORON IN WATER REACT WITH HUMANS?
Boron is an essential micronutrient necessary in our systems as it works in concert with vitamin D to increases our bodies ability to assimilate calcium for bone, tooth and brain tissue health. The best natural sources are dark green leafy vegetables, non-citrus fruits, dried fruits and tree nuts. There is also a correlation between boron levels in the body and the levels hormones especially of estrogen and testosterone which ultimately slows bone deterioration due to osteoporosis. Currently, the NIH is studying links between boron and effective cancer treatment by certain protocols.
Most information on the topic suggests a maximum intake of 3 milligrams daily. The USEPA does not have a mandated maximum level in drinking water, but has a suggested maximum level of 3 PPM for healthy adults and 2 PPM for children. The World Health Organization (WHO) has an established maximum of 2.4 PPM. California has a state-mandated limit of 1 PPM (expressed as 1,000 ug/l) and a number of other state drinking water regulations call for limits from 0.6 to 1.0 PPM.
Excess boron will affect people differently, but common reactions include nausea, indigestion, vomiting, headache and diarrhea. High levels over a long time can lead to rashes, hair loss and kidney damage. Fatal doses occur at 15-20 grams (15,000 to 20,000 mg)
4. HOW DOES BORON REACT WITH PLANTS?
Apparently, there is carryover of boron (as boric acid) in air over oceans and seas and this becomes the Jonny Appleseed propagation of boron in soil at a rate estimated in millions of tons annually. Typical soil levels of boron in soil vary from 5 to 80 PPM and are location and sea proximity dependent.
The extremely low level of boron required for optimum plant vitality is a classic example of Liebig’s Law of Minimums which in plant applications states that unless a minimum level of a key micronutrient is provided, growth is compromised regardless of feeding excess amounts of other nutrients. With adequate boron levels in the soil combining with microorganisms, calcium and phosphorus in particular are more effectively used by plants. Boron in the irrigation water is additive to the boron in the soil. Overall, proper boron levels combined with other minerals, nutrients and adequate water will produce plants with healthier cell walls, non-browning leaves, more rapid growth, better water transport throughout the plant and more productive seed and flower growth.
In some cases, higher levels of boron in the soil and/or irrigation water becomes too much of a good thing. The plants exposed to excess levels of boron for their species exhibit slower, stunted growth, browning of leaves and flowers and poor-quality fruit. It’s known that photosynthesis is inhibited by excess boron, but beyond that, the precise reason for plant damage by excess boron remains elusive in 2021.
5. IF BORON LEVELS ARE TOO HIGH FOR PLANTS, WHAT CAN BE DONE?
If it is a soil contamination issue, leach with low/no boron water from a river or lake repeatedly until soil samples from beneath the crop root level tests low enough to be satisfactory.
If boron is in the water above a safe level for the intended species of plant, Dime Water, Inc. can be of help. Boron has a very low surface energy which makes it virtually impossible to remove with standard reverse osmosis, so variants of seawater (desal) R.O. units must be employed with varying levels of success. The water waste, high energy use, high CAPEX and OPEX makes this a less than acceptable method in most cases. We therefore have developed a unique, regenerable filter with a medium that is selective to boron, is 90% plus water efficient and has a fraction of CAPEX and OPEX.
One of the most important elements dissolved in water used to irrigate cannabis plants (and others as seen in the chart below) is Boron.
Too little or too much will cause severe withering and discoloration of a plant which severely reduces monetary value. The typically expressed range is from 0.05 to 0.5 mg/l in the irrigation water.
Boron in excessive amounts in well water sources is found in the US particularly in California, Russia, and Turkey. It is also found in membrane desalinated seawater throughout the world.
lf too low or absent, a simple, cost-effective “fix” is to mix a small amount of very soluble boric acid crystals (H3BO3) in water and feed it into the irrigation stream with an inexpensive chemical feed pump. Because of common consumer uses of boric acid such as a laundry aid or a foot bath, boric acid is available in drug stores, supermarkets, and, of course, online.
If too high (above 0.5 mg/l) it must be reduced. One would think that reverse osmosis would be the ideal solution. It is not. Reverse osmosis doesn’t reduce dissolved solids by forcing water through microscopic holes in the membrane, but instead by repelling charges between the membrane and the element (ion) in solution. Boron has no discernible charge so it passes through membranes. Even high-pressure seawater membranes allow too much through. Seawater can contain 5 PPM or more boron.
The removal is best accomplished using an extremely rare and expensive resin that is uniquely capable of being selective to boron and not blinded by other elements in the water. This feature permits minimal and relatively inexpensive pretreatment. The resin must be stripped of the boron with hydrochloric acid (HCl) and then returned to a boron removal state with sodium hydroxide(NaOH). The use of these chemicals in a sequential pattern necessitates special materials of construction and very unique controls for safety and efficacy.
Boron upper levels to minimize toxic sensitivity in mg/l*
<0.5 blackberry, cannabis
0.5-1 peach, cherry, plumb, grape, onion, garlic, sweet potato, wheat, barley, sunflower, strawberry
1-2 red pepper, pea, carrot, radish, potato, cucumber
2-4 lettuce, cabbage, celery, turnip, oat, corn, artichoke, tobacco, mustard squash
4-6 Tomato, alfalfa, parsley, sugar-beet
6-14 asparagus
* Information provided by the Australian Department of Agriculture
