Boron Deficiency
During the Micronutrients Workshop, Professor Dr. Suleyman Taban of the Department of Soil
Science and Plant Nutrition, Faculty of Agriculture at Ankara University, discussed “Boron
Fertilization in Boron Deficiency Soils and Crops”.
Boron is a unique non-metal micronutrient that is necessary to support the normal growth and
development of plants. While boron is required by higher plants, its functions as a micronutrient are
not fully understood, Dr. Taban asserted. However, research has established that boron has key
roles to play in plants in carbohydrate and protein metabolism, tissue differentiation, auxin and
phenol metabolism, membrane permeability, cell elongation and cell division, pollen germination
and pollen tube growth, cell wall synthesis, cell wall structure integrity, lignification, RNA and IAA
metabolism, respiration, and in cell membranes.
Boron (B) deficiency is acknowledged as the second most important micronutrient constraint in
crops after that of zinc on a global scale. Symptoms indicating B deficiency can appear in crops;
these can be confirmed by plant and soil analyses. Studies suggest that B deficiency is one of the
major constraints on crop production worldwide and have been reported in more than 80 countries
and for more than 132 crops over the past 60 years or so. Considerable reductions in yield due to B
deficiency have been reported for a wide range of crops, including cotton, rice, maize, wheat,
soybean, groundnut, canola, citrus fruit and alfalfa. Thus, considerable net benefits can accrue if B
deficiencies are properly addressed, Dr. Taban argued.
The amount of B in a soil depends on the parent materials from which the soil originated. B is found
naturally as a borate mineral and in combination with silicate, forming complex borosilicate minerals
such as tourmalines.
B deficiency has been commonly reported in highly leached soils and those based on calcareous,
alluvial and loessial deposits. A variety of factors may result in soils deficient in B. Low soil organic
matter content, sandy texture, high pH, agricultural practices incorporating regular liming, drought,
intensive agriculture, higher nutrient uptake than application, and the use of fertilizers low in
micronutrients are considered to be the main factors associated with an occurrence of B deficiency.
Dr. Taban provided a list of countries where B deficiencies had been recorded basis favourable plant
responses to applications of B. In Europe, the list comprises 29 nations – Albania, Austria, Belgium,
Bulgaria, Croatia, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland,
Italy, Kosovo, Netherlands, Norway, Poland, Portugal, the Russian Federation, Serbia, Slovakia,
Spain, Sweden, Switzerland, Turkey, and the UK. In Austral-Asia, 19 countries have been identified,
namely, Australia, Bangladesh, China, India, Indonesia, Iran, Japan, Korea, Malaysia, Nepal, New
Zealand, Pakistan, Philippines, Papua New Guinea, Saudi Arabia, Sri Lanka, Taiwan, Thailand and
Vietnam. In North and South America, a total of 12 countries are reported to suffer from the same
problem, including Argentina, Brazil, Canada, Chile, Colombia, Costa Rica, Ecuador, Mexico, Peru,
Puerto Rico, the USA and Venezuela. In Africa, 25 countries are similarly affected, namely Algeria,
Angola, Benin, Botswana, Burkina Faso, Cameroon, Central African Republic, Chad, Congo, Egypt,
Ghana, Ivory Coast, Kenya, Madagascar, Malawi, Morocco, Mozambique, Nigeria, Senegal, South
Africa, Tanzania, Tunisia, Zaire, Zambia and Zimbabwe. In order to address these deficiencies, B
fertilizer products must be used.
Boron reserves are not distributed evenly throughout the world; boron is mined in relatively few
locations. In 2012, Turkey accounted for 72.5% of world reserves of boron; reserves elsewhere are
small in comparison, with 7.7% of world boron reserves located in Russia, 6.2% in the USA, 3.6% in
China and 3.2% in Chile. In 2012, world boron production totalled almost 4 million tonnes (1.9
million tonnes B2O3); Turkey produced 47.2% of this total, followed by the USA (27.6%), South
America (15.8%) and Asia (9.4%).
In Turkey, borate deposits are located in the four main districts of Western Anatolia. In terms of
borate sources in Turkey, Colemanit dominates, accounting for about 76% of total Turkish borate
reserves, followed by Tincal (22%) and Ulexite (2%). In Turkey, ETiMADEN manufactures and sells
various grades of boron fertilizers. These include Etidot 67 (a very soluble, easy to use material),
Etibor 48 (for use in the production of powdered and granular NPK) and boric acid (the normal
sulphate product used in the production of liquid fertilizer). Etidot 67 is sold as a powder which
contains a minimum of 67% boron trioxide and 14% sodium oxide, and is guaranteed 99.9% pure.
Etibor 48 granular, which contains a minimum of 48% boron trioxide and 21.37% sodium oxide, has a
larger particle size (91% between 0.075 and 1.18 mms). The powdered variant of the same product,
which contains a minimum of 47.8% boron trioxide and 21.28% sodium oxide, has up to 50% of its
particle content below 0.075 mms. ETiMADEN’s boric acid, with a 56.25% minimum boron trioxide
content, is a granular technical grade product (minimum 92% content in the size range 0.063 mms to
1.00 mms).