The Boron Secret

Boron is a mineral element described as essential, this means that in its absence, plants do not complete their physiological cycle, generating a seed (offspring) capable of germinating and developing. In addition to being essential for plant development, this nutrient is required throughout crop development.

Boron can be characterized as a structural nutrient, since more than 90% of the total boron in a plant is concentrated in cell walls and membranes (Hu & Brown, 1994), structures responsible for giving shape and rigidity to plant cells. . Therefore, a typical symptom of deficiency of this element is the poor formation of plant organs. Probably the most common and immediate impact is on root growth. Studies by Kobayashi et al. (1999) demonstrate that hours after inducing boron deficiency in plants, a reduction in root growth is already observed.

In addition to its structural function, boron participates in metabolic functions, such as DNA transcription, essential for cell multiplication or the remobilization of carbohydrates, with particular emphasis on magnesium and potassium, essential for the grain filling process. 

In the soil, B is found in silicate minerals, adsorbed on clay minerals, in organic matter (OM) and in aluminum and iron hydroxides (Dechen & Nachtigall, 2007). Available B is found in the surface layers of well-drained soils and OM is an important source of this element for plants, through the mineralization process. Soil texture also influences the availability of B, with higher levels of the element being expected with increasing clay content. In sandy soils there may be greater leaching of the nutrient, carried by the flow of rainwater that removes it from the productive environment.

In addition to its described essentiality, studies by Blevins et al. (1998) describe synergistic effects between boron supply and potassium absorption, just as root phosphorus absorption can be reduced under conditions of boron deficiency, basically due to the fact that boron stimulates a cell membrane structure called the sodium-sodium pump. potassium, responsible for the polarization of cell membranes and consequent generation of force for active root absorption of phosphorus and potassium. 

Despite all this functionality, the element is required in small quantities, around 0,35Kg/ha for a soybean productivity of 80sc/ha, while nitrogen demand exceeds 300Kg/ha.

So far it seems easy, however, making boron available, even in small relative quantities in the surface layers of tropical agricultural soils throughout the entire crop cycle is not, a priori, an easy mission.

Unlike the “rule” of nutrients that ionize when in soil solution, which results in the formation of electrical charges, and consequent retention of soil charges, boron in agricultural environments remains in its molecular form (H3BO3), thus not having , resulting electrical charge. This leads to the element being heavily exposed to movement according to the water flow, which can result in losses.

Globally, several studies indicate that boron deficiency is one of the most prevalent among micronutrients (Shorrocks, 1997). In a survey carried out by Abreu et. al. (2005), more than 13.000 soil samples from 21 Brazilian states, 40% showed low levels of available B (<0,2 mg dm-3).

Despite this great dynamic in the soil, boron has very low mobility in the plant, which makes foliar input very limited. According to a study by Boaretto, et al. (2007), in citrus, only 3,2% of the boron absorbed via the leaves was translocated by the plant 240 days after application. If that were not enough, boron sources are limited and often have low efficiency, as they make all available boron immediately available, exposing it to losses or risk of toxicity, in addition to the operational burden of application/distribution. 

As a solution to this problem surrounding boron management, Mosaic Fertilizers developed Aspire, a fertilizer that, through the patented Nutriform technology, combines two sources of boron with potassium particles, ensuring boron for the initial demand, with security of availability. until the end of the crop cycle. According to a study by Da Silva et al. (2018), the use of Aspire results in a more uniform spatial distribution of boron and reduces risks of toxicity or losses due to leaching, by providing better synchrony between nutrient availability and crop demand. In more than 200 comparative fields in commercial areas in Brazil, Aspire increased soybean productivity by 2,9 sc/ha, when compared to standard farm management.

Do you want to know more about Aspire and the other performance fertilizers from Mosaic Fertilizandos? Visit www.nutiçãodesafras.com.br.

Alan Bueno Silva Ataíde
Senior Agronomist Mosaic Fertilizers

REFERENCES
ABREU, CA; RAIJ, B. van; ABREU, MF; GONZÁLEZ, AP Routine Soil Test to Monitor Heavy Metals and Boron. Scientia Agricola, 62:6:564-571, 2005.
BLEVINS, Dale G.; LUKASZEWSKI, Krystyna M. Boron in plant structure and function. Annual review of plant biology, v. 49, no. 1, p. 481-500, 1998.
DECHEN, A.R. & NACHTIGALL, G.R. Elements required for plant nutrition. In: NOVAIS, R.F.; ALVAREZ, V.H.A.; BARROS, N.F.; FONTES, R.L.F.; CANTARUTTI, R.B.; NEVES, J.C.L. eds. Soil fertility. Viçosa: Brazilian Soil Science Society, UFV, 2007 p. 91-132.
DA SILVA, Rodrigo C. et al. Slow and Fast‐Release Boron Sources in Potash Fertilizers: Spatial Variability, Nutrient Dissolution and Plant Uptake. Soil Science Society of America Journal, vol. 82, no. 6, p. 1437-1448, 2018.
Hu, H. and Brown, P. H. (1994) Localization of Boron in Cell Walls of Squash and Tobacco and its Association with Pectin (Evidence for a Structural Role of Boron in the Cell Wall). Plant Physiolgy, 105, 681-689.
Masaru Kobayashi, Maako Miyamoto, Toru Matoh, Sakihito Kitajima, Shigeru Hanano, I Nyoman Sumerta, Takafumi Narise, Hideyuki Suzuki, Nozomu Sakurai & Daisuke Shibata (2018) Mechanism underlying rapid responses to boron deprivation in Arabidopsis roots, Soil Science and Plant Nutrition, 64:1, 106-115, DOI: 10.1080/00380768.2017.1416670
Rodrigo Marcelli Boaretto, José Antônio Quaggio, Dirceu Mattos Jr., Takashi Muraoka & Antonio Enedi Boaretto (2011) BORON UPTAKE AND DISTRIBUTION IN FIELD GROWN CITRUS TREES, Journal of Plant Nutrition, 34:6, 839-849, DOI: 10.1080/01904167.2011.544353 .XNUMX
Shorrocks, V. (1997) The Occurrence and Correction of Boron Deficiency. Plant and Soil, 193, 121-148.