by Christian Schmalz, MBA Marketing Director, UlexAndes-USA

The role of micronutrients in plant development, and consequently the impact of micronutrient deficiencies, is well researched. Despite the rather small quantities required, these micronutrients play a complex role in crop development and health. Deficiencies result in poor growth and low yields. Of the micronutrients, Zinc (Zn) and boron (B) continue to be the most universal plant nutrient deficiency. Boron’s (B) role as a critical micronutrient is widely accepted; yet compounding approaches continue to evolve as growers and suppliers seek value-added approaches for greater returns on investments (ROI’s). Acknowledging expert opinion regarding the benefits of micronutrients, the goal of the following is to further the understanding of boron (B), second only to zinc (Zn) in its criticality as a micronutrient.


Boron occurs naturally in many forms of borates and is distributed in oceans, sedimentary rocks, coal, shale and soils. Borates are primarily mined in arid geographical regions, yet economically viable concentrations are limited to California, Turkey and South America. Structurally, borates are interlocking chains of Boron, hydroxide, water, calcium and sodium. Borates have hundreds of applications, however an overwhelming majority is used in glass and ceramics; soaps and detergents; fire retardants; and agriculture. Boron consumption as an agriculture component occupies a small percentage of the worldwide borates market.

Shown to be an essential micronutrient for plant growth by Warrington in 1923, boron (B) was studied extensively in the 1950’s during the space race as a potential super fuel. Boron chemistry benefited greatly from this investment of millions of dollars, rubles, and pounds. Initially attractive due to the intense heat generated by burning its hydrides (boranes), the discovery of new borane anions and carboranes (mixed hydrides of carbon and boron) were ultimately featured works of many Nobel Laureates (Wade).

One critical subclass of borates is the structurally complex mineral, Ulexite. Named after the German Chemist George Ludwig Ulex, Ulexite is a unique sodium-calcium borate mineral found with large-scale gypsum deposits in playa and salt marshes located in arid regions of the USA, South America, Turkey, Russia and China. Ulexite accumulates in these intermittent lakes due to nearby mountain runoff during rainy seasons. Once the water evaporates, significant deposits are left to behind approximately 4-5 meters below the surface.

Boron is a mobile soil nutrient due to its very soluble anionic form in soil. Additionally, its chemical makeup factors into its solubility characteristics. Sodium borates are faster acting, and more prone to leaching. Calcium borates are more slowly mineralized. Typically, Ulexite contains ~60% calcium borate, ~40% sodium borate. The solubility of Ulexite is related to its particle size and the proportion of these two borates, thus explaining why it is sought after for agriculture use Not only will this produce a fast acting product (from sodium borate), but it will also exhibit time release properties (from calcium borate) more closely mirroring crop demands.


With offices in the U.S. and South America, international companies like UlexAndes, export high quality granular boron (B) to countries worldwide through Chilean and Peruvian ports. To do so, they have had to developed cost-efficient processes to transform the raw material Ulexite into high-grade granular boron (B). Ulexite deposits are extracted and transported by rail from high in the Andes mountains (4200-4700 meters above seal level) to production factories for further refining. There it is crushed and washed to extract impurities such as chlorides and sulfates (sodium and calcium). Once the granulated ulexite ore emerges, it is passed through a LP gas dryer and then natural sunlight for drying. Ulexite ore is then finely ground and screened before it is granulated.

Boron can added to compound fertilizers in various forms including powdered, granular, soluble form, or even applied individually. UlexAndes also provides Assay guarantees of heavy metal concentrations, made-to-order granular compounds or straight elements. Pricing for boron materials is typically based on the geographic supplier, boric oxide content (which varies by ore compound) and on the presence or absence of sodium and calcium. Compared to alternatives, Ulexite’s cost per unit boron is highly attractive.


Nutrient management is a basic requirement for plant growth. Understanding how to efficiently manage mineral micronutrients to maximize soil fertility is vitally important in crop production. Boron is required for all plant nutrition to maintain plant function. (see Table 1).

Boron soil levels should be approximately 0.4ppm. Certain crops are sensitive to boron (B) applications, while others have higher requirements. Alfalfa, for example has a higher boron requirement than most crops. Corn on the other hand is very sensitive to over-application of boron. Crop yields respond rapidly when nutrient deficiencies are corrected to the point of agronomic optimum rate. Because it is relatively easy to apply too much, it is very important to get uniform mixing and application, especially when applying in bands or foliar. Thus, given boron’s (B) tendency for leaching, applying a product that is available over a wider range of the growing season is important.

Boron (B) deficiencies are compounded by not only high soil pH and arid conditions, but wet climates where leaching from heavy rainfall or irrigation leads can be problematic, particularly in coarse-textured soils. Conversely, accumulation can occur in heavier textured clay soils in semi-arid regions. Common indications of boron deficiencies are shown in Table 2.

Plants require each nutrient to be taken up in an ‘ionic’ form with the exception of boron (B), as boric acid (H3BO3). Boron’s optimum concentration in plants is 6-60ppm. Boron typically occurs as a neutral boric acid molecule when soil pH is <8.0

A solid micronutrient plan not only increases ROI, it is a value added proposition for growers and suppliers alike. Numerous options abound from many companies.  It is important to be able to craft an appropriate plan from the numerous product lines available.  UlexAndes is an example of one international company that formulates several product lines tailored for specific crop situations. Relying on their close proximity of high quality minerals in Peru and Bolivia, and the expertise of accomplished agronomists and chemical engineers, micronutrient compounds can be specially formulated to meet customer demands or be developed to meet specific needs.

Two UlexAndes products that correct a majority of boron deficiencies are their ‘time release’ products Boron 10 and Boron 15 Maxi Granule. Not only are both products OMRI certified, both Boron 10 and Boron 15 Maxi Granule are unique blends of sodium-calcium borate minerals, compounded to maximize the ground application benefits for a wide range of plant species. Applied as a component or in multi-nutrient granular bulk blend, Boron 10 and Boron 15 Maxi Granule offer a slow boron release consistent with the gradual uptake of boron required by plants throughout the growing season. These types of controlled soluble borates greatly increase the availability to plants, while substantially reducing the potential for leaching. Recognizing the critical micronutrient needs for both Zinc (Zn) and Boron (B), UlexAndes is launching their new 11-6-6 Zinc/Boron/Sulfur (ZinBor S MAXI) compound just in time for the fall season. This specially formulated new product, using proprietary  ‘fusion technology’, will perfectly complement any micronutrient plan.  More information can be found at