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Silicon in Agriculture

Introduction

This the largest and most developed of all the HORTCOM themes and constitutes a useful point of reference on the subject, essentially for growers, agronomists and the supply industry. Throughout the blog, the word silicon refers to the BIOACTIVE PLANT AVAILABLE molecule which is principally MONO-SILICIC ACID. In order to simplify this term, the author uses Bioactive Silicon (BAS) to describe its action once it is drawn into the vascular tissues of a plant, while Plant Available Silicon (PAS) describes the life and actions of the molecule, externally, in the soil-water-rhizosphere.

The value of this molecule to growers, farmers and the agroalimentary industry at large, is widely overlooked and requires education. The major problems concern the description and non-classification of Silicon by agricultural, Customs and other regulatory authorties. The leading Partner companies for this blog are: IGNIBRITE INC, USA; REXIL-AGRO BV, ILSA

 

Silicon is not listed as a fertilizer, nor an essential element. Instead, it sits unhappily in the category BIOSTIMULANT, unhappily because its actions against Abiotic stresses are noted, but the accepted definition of precludes any action against biotic stresses, despite the fact that it is well noted that silicon increases the resistance of plants to insect pests and diseases. Worse still, silicon is often not included as a distinct entry in lists of different types of Biostimulant.

 

Consequently, Agricultural authorities and Customs have their hands tied and cannot list silicon. Notable exceptions include: AAPFO (American Association of Plant Food Control Officials), the EPA (Environmental Protection Agency) and the OMRI (Organic Materials Review Institute). Where legislation is inadequate, the only way round is to consider silicate salts (e.g. calcium silicate) where the calcium qualifies as an essential element, and the salt as a fertilizer. In the soil calcium silicate slowly releases PAS. Other suppliers of liquid stabilized mono-silicic acid, add essential elements such as boron and zinc, to qualify the substance as providing essential micronutrients, not because of the silicon.

 

Or indeed in some formulations the silicon molecule is combined with other organic or inorganic substances so that it becomes difficult to tell what molecule is doing what and why.

 

Furthermore, the action of silicon in reducing plant requirements for fertilizers, water and pesticides does not appeal to BigPharma (the agrochemical industry). Lastly, because of the activity of PAS in the highly dynamic soil-water-microbe-rhizosphere environment, it is difficult to accurately measure its quantity in a sample of soil at any given moment.

 

Fortunately however, through further RESEARCH AND EDUCATION, silicon is continuing to emerge as a very important substance to sustainable agriculture, biological production and post-harvest. It is rare that an element is beneficial in such a large and diverse range of  functions. In reality some agricultural authorites now accept silicon as a BENEFICIAL ELEMENT for plant growth and development and many scientists are happy to describe silicon as a QUASI ESSENTIAL ELEMENT.  So it is that growers throughout the world have for many years gained considerable benefits by applying silicon as a foliar spray or soil dressing. This practice  is set to significantly  improve as research begins to explain why and agricultural authorities accede to a revised classification. See ISSAG (International Society for the Application of Silicon in Agriculture). To complete the introduction, see ‘The Big Picture’ (pdf in English and Italian) in support of the above statement.

Scientific ‘Silicon’ Journal. In the description by the bimonthly scientific journal ‘SILICON’ published by Springer, Netherlands, silicon is described as the most important element of the 21st Century!

The rapidly increasing amount of research conducted on the effects of silicon in plant growth and development and agriculture in general, supports HORTCOM’s attempt to distill and present such information of use to growers, agronomists together with silicon supply companies and experimental stations to realize their own trials focused on the production and distribution of specific crops and commercial necessities.

The journal’s coverage is unique in presenting all areas of silicon research and development across all disciplines including agriculture and environmental science. The silicon community is in the midst of aggressive research initiatives with significant R&D efforts continuing in crystalline and amorphous silicon, silica, silicones, silsesquioxanes, silicon carbide, silanes and silicates to name a few.

BIOACTIVE, PLANT AVAILABLE  SILICON

Silicon, like many other mineral elements is not an independent operator. The plant available bioactive molecule mono-silicic acid (usually together with di-silicic acid) might be classified as a biostimulant but more precisely, it acts as a soil conditioner, anti-stress bio-regulator and structural component. In these roles, it is necessary to consider the effects of PAS/BAS and polysilicic acids in connection with the availability and uptake of ‘other’ essential minerals from the soil, their influence on soil structure, soil microorganisms, plant stress dynamics, post-harvest quality, plant metabolism, gene transcription, resistance to insects and diseases, because silicon has beneficial effects in ALL of these areas. See The Big Picture. A very good introduction to the action of PAS in the soil can be found on the Harsco video for its product Crossover.

A more holistic approach is therefore necessary to appreciate the role of silicon, since there are no sealed compartments or isolated actions in ecosystems. A more holistic multidisciplinery approach also favours conferences that deal with silicon in the wider context of mineral nutrition, e.g. the IPNC (International Plant Nutrition Colloquium) Copenhagen, August 2017. See IPNC and Proceedings direct.

Education: There are a number of learned books and e-books on the effects of Silicon in agriculture but few are addressed to the grower and agronomist in a practical, technical sense. If agriculture (all sectors) is to benefit from the application of silicon-based formulations, the KEY is education where teachers, students, extension services and growers, see silicon as an important protagonist alongside calcium and NPK because of its very wide ranging, albeit subtle, effects on sustainable agriculture, food quality and security. Research needs to be trasformed into INNOVATION in terms of crop production, post-harvest and internal produce quality. BAS is also important for human and animal nutrition. Lastly, for the scientific community and agricultural authorities, pure research and development work is slowly but surely consolidating itself and networking throughout the world in the ISSAG  (International Society for the use of Silicon in Agriculture).

Italian horticulture and agriculture is one of the world leaders in biological and sustainable production further strengthened by its booming wine and agroalimentary industries. Interest in PAS/BAS has been slow, due to the plethora of different biostimulants on the market. Also in view of the relative lack of knowledge on the beneficial effects of silicon on post harvest characteristics and nutritional quality, despite grower trials organized by  ILSA /Agro-Solutions that lead to the Silicon Day in Bologna 2009 (see later refrences). This attitude is now changing and current silicon supply companies include: ILSA SPA (-PT now associated with Biolchim) / Cosmocel SA (-PT Maxitalianway for Italy)  www.maxitalianway.it / LEA Srl (Laboratori Europei di Agrobiotecnologie for Armurox (Bioiberica – PT)/ De Sangosse Italia Srl (Siligo and other silicon based products under development) / Green Has Italia Srl (Silvest) www.greenhasitalia.com / Compo Expert Italia SpA (Agrosil LR) / K+S Italia Srl (Sil-Ca) www.kali-gmbh.com / Caprara Srl (Special products for agriculture) www.caprara.it / LC TEC (Laboratori chimici e biotecnologici) www.orpc.it / Alba Milagro SpA.  A note should be made of the International Horticultural Expo at Bologna 1st May – 31 October, 2019 set to present the Italian horticultural, nurserystock and agroalimentary industry to the world. The theme is: GROW GREEN, EAT GREEN, LIVE GREEN. Some 2.5 millin vistors expected, 500 exhibitors and 50 countries represented: a great opportunity for supply companies to give silicon a good airing to all parts of the supply chain to final consumers, of the potential of silicon to reduce the use of agrochemicals and water and improve postharvest and nutrutional values (especially mineral and vitamin content).

Per quelle aziende/ organizzazioni che sono PARTNERS, non esitate a chiedere un preventivo per le traduzioni in italiano di parti delle pagine; si applicano tariffe speciali.

The book ‘Silicon Solutions’ by Edward Bent, ISBN: 978-88-6642-151-1), 2014 Sestante Edizioni. (See also SALES & SERVICES). pdf) Presentation by Edward Agronomy Department of UNIMORE  (University of Modena and Emilia Romagna) 2018. Book Flyer  In his practical research, he also considers the different prerogatives of pure science, the supply industry and crop production (pdf) How pure is our science?

Few books (if any) have attempted to transform academic information (scientific papers) into a form more accessible to the practical interests and needs of growers and agronomists. As such it is the first of its type and constitutes an important ‘primer’ for course work in agricultural schools, colleges and universities. Of particular note, it also emphasizes the important contributions that silicon can make to improve internal quality of produce and post-harvest characteristics in terms of nutritional value, packing, transport, storage and distribution effects postharvest. While not peer reviewed, the book is useful and valid introduction to the argument and referred to by the ISSAG.

The author would like to make contact with a publisher or organization, interested to print up-dated digital ebook version of this book. Also for the publication of Spanish and Italian language editions. Significant requests have been forthcoming but the distribution wider a field of printed books of this type is limited. 

PRODUCT ACTION & CATEGORY?

Biostimulants. The global interest in this category of product is rapidly increasing, mirrored by the booming international market for conferences on biostimulants, following greater control or ban on the use various traditional plant chemicals and the upsurge in biological (organic) or at least integrated production systems. A quick look online reveals over 25 international conferences, congresses and summits concerning biostimulants in 2018, excluding Asia and the Middle East. Events appear to be concentrated in the periods March-April and September-November. Researchers and experts are hard pressed to give presentations in response to invitations from so many venues round the world. Some lists of events: EBIC, NewAg conferences, Biostimulant Coalition.

There is need for further research on the effects of biostimulants also to underpin proper legislation and product recognition by agricultural authorities. It is quite normal for government authorities to require the repetiton by agricultural scientists of the more significant trials undertaken by growers and experimental stations, more especially when conducted in other countries, and the results published after appropriate discussion and funding; implying a lag-time of 3-4 years. Furthermore, in contrast to agrochemicals that eliminate problems, biostimulants tend to work directly or indirectly in more subtle less obvious ways. More applied research is necessary to better understand the processes involved and to convince growers to use biostimulants (INCLUDING SILICON-BASED SUBSTANCES) given a separate class in all lists of different types of biostimulants.

But the sheer volume of different biostimulants already on the market with ‘all-inclusive’ and overlapping claims by suppliers, represents a problem not only for agricultural researchers but also for growers trying to make the most cost-effective choice of what to use. A problem for research is that many biostimulants are preventative and/or stimulate growth but the effects are often not big enough to stand out in comparison to the more obvious curative effects of agrochemicals. In the case of silicon, the molecule is often combined with various other minerals and substances the effects of which can be synergic. What is the grower to do in this veritable jungle of different biostimulants and claims? What information can growers trust?

Perhaps the best way forward is for growers to take control and engage in their own trials in collaboration with an agronomist, silicon supply company and local experimental station. They are the ones who stand to potentially gain or otherwise from such products. Their trial results can then be offered to agricultural scientists to create further experiments and production protocols. In the case of PAS/BAS, chapters 11 and 12 of the book ‘Silicon Solutions’ consider this important aspect.

The definition of a biostimulant accepted by the EBIC’s (European Biostimulants Industry Council) is any substance that can have positive effects against abiotic stress but not againt biotic stress since they do not eradicate insect pests and fungal diseases. Instead, the well-documented indirect but nonetheless important effects of silicon to biotic stress; to strengthen plants and improve their resistance to infection are not considered. In this context note the following video presentations: Dr. Lawrence Datnoff, Dept. of Plant Pathology and Crop Physiology, Lousiana State University Agriculture Centre. See also the presentation by Michael Gauthier, R&D Manager at Les Fraise de L’ille d’Orlien on the effects of silicon on fungal diseases of strawberries. See also pdf presentation by Dr. Henk-Maarten Laane at the Agronomy Department of UNIMORE, University of Modena and Emilia Romagna 2018. A useful review by Dr. Achilea, can be found in the June/July issue of NewAg International 2018 (editions in English, Spanish and Cinese), entitled ‘Silicon Products: Dual use against Biotic and Abiotic stress!’ NewAg International.

Innovation then takes time. It implies a change in thinking and a change towards more natural ways of growing plants to obtain better results and more sustainable agriculture. Above all it requires applied research and education to turn scientific discovery into innovative solutions. Vested interests and old legislation have to be reviewed.

Proper legislation. The way forward for silicon is through enlightened legislation. Its registration for use in agriculture by authorities in the USA has lead the field for some time. The  APPFCO  (American Association of Plant Food Control Officials) regulates the labelling of fertilizers and now classifies silicon as a beneficial substance enabling it to be sold throughout the States for horticultural, turf and agricultural use. Sil-Matrix from PQ Corporation is registered by the EPA (Environmental Protection Agency) and certified by the OMRI (Organic Materials Review Institute) as an organic pesticide for preventative control of powdery mildew, mites and aphids in certain high value crops. Such categorization and authorization has been (and still is) one of the biggest obstacles to a greater use of silicon in agriculture. Describing silicon as just a biostimulant is certainly inadequate in the light of scientific research the approval of its use and preventative action against insect pests and diseases (biotic stress).

Modern agriculture is also focused on the re-generation of soil fertility based on thriving populations of microorganisms. Conditioners and biostimulants that contain strains of bacteria, mycorrhizal fungi and nutrients are highly beneficial when added to the soil. The effect is also positive for plant growth and depuration of soil. Silicon inserts itself perfectly in this dynamic, adding important benefits to soil structure, growth of microorganisms and the plants themselves, above and below ground, and in soil depuration especially from heavy metals. Soils habitually used for intensive production become compacted, loose their microbial life and fertility and require greater quantities of fertilizer and plant chemicals to obtain similar crop yields. Internal produce quality declines (sugars, vitamins, anti-oxidants, minerals and other vital substances), made worse by the accumulation of chemical residues. The application of PAS/BAS provides the basis for sustainable agriculture with significant reductions in the need for fertilizers, plant chemicals and irrigation water. See Introduction video by Dr. Wendy Zellner, Research Plant Physiologist at the USDA ARS. See; Silicon Review Rutgers pdf.

Tests for PAS. Beneficial effects of applying silicon-based products to agricultural crops are widely accepted but results tend to be crop specific (different responses for different species, genera or family) and unclear if a crop is not clearly suffering from silicon deficiency (a commonly found condition in many soils and soilless media, not immediately evident to growers). Only when growth and development is stimulated by the application of additional silicon (PAS/BAS) do the effects become clear. The amount of PAS in the soil in relationship to the total quantity of silicon can be determined, although none of the tests are simple and results tend to be variable in accordance with the complexities of the highly dynamic soil-water-microbe-root environment. However, the sodium carbonate – ammonium nitrate extraction method has been officially accepted by the AAPFCO.

Above Image of Henk Nieudorp in one of the first SSA trials in Holland. See also reference to one of the later later formulations Siliforce and strawberry trial 2014.

Soluble aluminium. It is well known that PAS binds strongly to soluble (reactive) aluminium released from clay content when many soils become acid through intensive use. Recent research with Soyabean has demonstrated the very damaging effect of soluble aluminium in the soil where in actively growing roots, it binds onto and enters cell walls of a group of cells in the root cap, preventing root elongation. This stunting effect is very rapid and prevents the root system from obtaining water and minerals required for normal growth. P M Kopittke, K L Moore et al: “Identification of the primary lesion of toxic aluminium in plant roots”. Plant Physiology, April 2015 Vol 167 no.4 1402-1411. UQ:354053. Doi: Kopittke & Moore 2015

Stabilized silicic acid. Silicic acids are slowly released by hydrolysis from silicon containing clays, sand and rock in the presence of weak acids. These are mainly carbonic acid derived from respiration of plant roots, soil inhabiting organisms and microbes or from organic acid exudates. Mono-silicic acid however is very unstable and rapidly polymerizes to inactive polysilicic acids. Furthermore, in the complex soil-water relationships, some of the mono-silicic acid released is quickly sequestered by heavy metals such as Al and Mn, Phosphoric acid and organic substances. Another part is lost inside the plant during its uptake in the transpiration stream and successive deposition in cell walls, leaf cuticle and around the stomata as colloidal silica, silica gel and hydrated silica. This implies that a plant, even growing in fertile soil or substrate will often benefit by supplementary silicon applied to the leaves. So it is not the amount of silicon in the soil that matters but the amount of ‘unstable’ PAS/BAS. Many years ago at the University of Antwerp, Prof. Dirk Vanden Berghe (see Interview by Edward Bent pdf) succeeded to exploit the synthesis of ortho (repeat units of monomeric) silicic acid (SSA) stabilized with Choline.  For the first time this provided growers with the possibility of applying concentrated silicic acid (principally monomeric) directly to the leaves as a foliar spraycreating important new horizons in plant production, from agricultural crops, fruit and vegetables to grass, horticultural and ornamental plants. See Armurox from Bioiberica.

Q1. What silicon-based products aravailable to the grower (officially recognized or otherwise by the authorities)?

Silicon-based products are available in two basic forms, LIQUID and PARTICULATE. Liquid formulations can be divided into two categories: STABILIZED SILICIC ACID and a range of soluble SILICATE SALTS e.g. Potassium silicate and calcium silicate. Particulate substances are non-soluble but diatomaceous or zeolite earths can however be applied to the soil (also to leaves) in the form liquid microsuspensions. In general, larger quantities of these particulate forms are required to provide the same quantity of liquid forms (especially SSA) to the soil/leaf, but have the advantage of slow release in the soil over a longer period of time.

Today, stabilized silicic acid (SSA) is available in several liquid formulations for foliar application. The first is SSA in combination with molybdenum and zinc, the second, with molybdenum, zinc, boron, and copper, stabilized with PEG (polyethylene glycol) available as Siliforce® from Agro-Solutions BV (PT) www.agro-solutions.nl. A second series of formulations consists of OSAB3 (SSA also PEG stabilized, combined with boron and other mineral elements), marketed as SAAT (Silicic Acid Agro Technology) by ReXil Agro BV (PT) www.rexil-agrow.com. Both of these companies also supply other products that stimulate plant growth and are synergic whem applied together with SSA (e.g. L-amino acids). A third is SSA stabilized by Choline rather than PEG and marketed by Yara (YaraVita – PT) See: Actisil for Poinsettia_Yara.  A fourth formulation called Optysil is supplied by Intermag Sp. z o.o. (Poland -PT) marketed as stabilized mono-silicic acid containing 2% chelated Fe. There is some confusion (and duplication) over product origin, experimental trials, international patents, marketing, promotion, education, distribution and sales of stabilized silicic acid.

Five commercial trial reports in Italian on the application of stabilized ortho (monomeric/dimeric) silicic acid were presented at the ‘Siliforce Day’ 2009, Bologna, Italy,  sponsored by Agro-Solutions / Ilsa Group SpA These results remain pertinent even today. Siliforce Dossier Italian pdf. Article in Italian. In English see: Agro-Solution 08316

  1. A. Utilizzo del prodotto: come, dove e quando, Eugenio Babini;  B. Esperienza su uva e ortaggi da frutto, Antonio Melillo; Verifiche di campo su fragola, albicocco e patata, Gianluca Molinari; D. Esperienza triennale su melo e vite, Duilio Porro; E. Panorama delle richerche internazionali, Alessandra Trinchera; F. RMI Innovazione per l’agricoltura, Massimiliano Valentini; G. Programma convegno

Files from Agro-Solutions in English pdf: Siliforce Potato; Siliforce Table Grapes; Siliforce Strawberry; Siliforce Apricot; In Spanish: An early summary.

For Rexil-Agro BV the results from experimental trials made by Dr. Margit Olle at the Estonian Crop Research Institute 2016 on foliar application of Silicic acid on field peas and cucumber transplants can be found here.

Due to very low rainfall and constant winds, Lanzarote (Canary Islands) is an excellent place for stress-testing plants. In trials with SSA (Siliforce); leaves of grapevines were shiny and waxier reducing loss of moisture and fungal infection, under biological protocols, grape yields were greatly improved.

 

FOLIAR APPLICATION

The scientific community does not accept that foliar applied silicic acid can be absorbed by leaves yet many trials by growers and at experimental stations have demonstrated that foliar applied SSA does indeed provoke observable beneficial effects such as enhanced photosynthesis and stronger root growth. The below mentioned publication is important in this regard (2018). Experience by the author of trials in Lanzarote (Canary Islands) with foliar applied SSA on grapevines was convincing, not surprising given strong sunshine, constant water and wind stress.

An important scientific review on the effects of foliar application of silicon formulations by Dr. Henk-Maarten Laane, CEO of Rexil-Agro BV, is published in Plants (2018) DOI: 10.3390/plants7020045. This fully documented paper strongly suggests the need for further pure research on just how silicic acid is ‘absorbed’ by the leaf and translocated or how it triggers a long distance signaling mechanism that stimulates root growth. Such research is necessary to support the positive effects of foliar application promoted by silicon supply companies, grower trials and commercial production, when to date scientists have stated that silicic acid is not absorbed at leaf surfaces See: Paper pdf

SILICON FORMULATIONS

Q2. What other LIQUID formulations are available to growers?

There are various soluble silicon-based formulations available for application to the leaves and/or as a root drench. Some are simple silicate molecules, others more complex. The latter group is represented by Sirius and Rigel G (2 silicon-based formulations from Orion Future Technology -PT) www.orionft.com Their research with strawberry plants is revealing; after treatment with Sirius (silicon biphosphite) there was not only an increase in the thickness of the cuticle but also in the density and length of leaf hairs. The number of leaf hairs correlated with a lower level of powdery mildew Podosphaera aphanis presumably due to the obstacle to spore germination. (Dr. Avice Hall, University of Hertford, England 2011). OrionFT_Strawberry. An article in the NewAg International magazine June 2016 plant protection section, refers to work by Dr. G Percival at Bartlett Tree Research Laboratory, Reading University, UK on the successful use of Silicon phosphite (Sirius from Orion FT) to reduce apple scab (Venturia inequalis) Impressive results against fungal diseases have also been obtained using Orion’s product  Trident (a zinc, copper, silicon micronutrient complex with a malic/citric acid polymer chelate).

Foliar application of Carbon Silpower and Carbon Defence from FB Sciences to the cultivation of cucumbers resulted in significant reduction of mildew (Podosphaera xhantii, Sphaerotheca fuliginea) in susceptible varieties. The most effective treatment with Carbon Silpower reduced disease severity by as much as 87% compared to the control. Experimental results WFL. Carbon Silpower is described as low salt, noncarbonated, liquid potassium and silicon concentrate, while Carbon Defence as: low salt, noncarbonated, liquid phosphorous and potassium concentrate containing silicon fbsciences.

Q3. What PARTICULATE substances are available?

Many silicates are available as mineral earths, obtained (mined) mainly from pyrophyllite clays and diatomaceous soils and applied as soil dressings and root drenches. Most of these are insoluble but can be applied as sprays intended mostly for the soil in the form of SUSPENSIONS OR MICRO (MICRONISED) SUSPENSIONS.

Particulate silicon-containing substances can be classified as fertilizers because they also make mineral elements other than silicon available to the soil (e.g. calcium from calcium silicate or potassium from potassium silicate). Another advantage of silicates over SSA is the potential slow-release of silicon to the soil; slow-release has been demonstrated with diatomaceous earth and zeolites or coated calcium ammonium nitrate containing silicon.

An important supplier of diatomaceous earth is Agripower Australia Pty Ltd See: Presentation Agripower pdf Diatomaceous earth AgriPower pdf. For information on a selection of other suppliers: AgrowSil_Harsco See: instructive video / AgSil_PQ Corporation  / Si for Turf Grass_Rutgers / Sil-Matrix PQ Corp When diatomaceous earths are applied as fine dust they also kill insects by dessication and reduce soil borne fungal pathogens such as Pythium and Fusarium. www.agripower.com.au / Nutrifert Role of silicon pdf  /  www.nutrifert.com.au  /www.naturalti.it.

MontanaGrow (USA) -PT supply an amorphous volcanic tuff (ignimbrite) for various sectors, including crop production and the raising of pigs and poultry MontanaGrow and some research projects See also the video on the benefits in chicken and egg production.

The Australian company Advanced Plant Nutrition produces Maxsil™, a calcium silicate derivative from waste glass, ground to a fine poweder made up of spherical granules after other additives have been added. Application rates of about 100kg/ha are being tested on sugarcane. There is also a liquid suspension available. It is claimed that MaxSil can replace up to 50% of normal application of phosphate in traditional fertilizer treatments. www.maxsil.com.au

Cosmocel SA, Mexico, supply Barrier, described as a liquid suspension containing 10% calcium and 24% silicon for foliar application or to the root substrate. See: Cosmocel SA and Barrier. Barrier/ Agri Nova from Spain supply SiliSec a micronized silica (7-9 microns). There is also a liquid suspension available.

When presented by the TYPE OF SILICATE SALT rather than whether liquid or particulate, the following list includes some of the most important products and supply companies:

Calcium silicate fertilizers ( + Mg) are available as: AgrowSil and Crossover from Harsco (PT) – www.harsco.com.

Potassium silicate formulations are available from companies that include: ZacSil (Zaclon LLC – www.zaclon.com) Sil_Matrix (Certis USA – www.certisusa.com  and their introduction to silicon http://certisusa.com/pdf-technical/silmatrix_SILICON.pdf /AgSil (PQ Corporation – www.pqcorp.com), SiKal (Yara Industries – www.yara.com). Nutrafeed Liquid Silica from Barmac www.barmac.com.au Sil-K from Plant Food Company (USA) www.plantfoodco.com

Q4. In what ways then does silicon function in plant growth & development?

To summarize this blog page, silicon acts as a soil conditioner, anti-stress bio-regulator and structural component. Soil conditioner in terms of the role of polysilicic acids in creating bridges between soil particles and the role of mono-silicic acid in the orchestration in the availability and uptake of other mineral elements (See Harsco’s video on Crossover). Also in the relative tolerance of plants to accumulation of certain other mineral elements that otherwise would become toxic. Mono-silicic acid is also important to soil microorganisms and to reducing the potentially damaging effects of heavy metals. As an anti-stress bio-regulator silicon has many functions some of which are only beginning to come to light. It has a role in stimulating the plant immune system and regulating the dynamics of cellular stress. It has been found to stimulate the synthesis of chlorophyll thereby enhancing photosynthesis. These functions appear to be underpinned by an involvement in the genetic transcription process where specific metabolites (mainly proteins) are synthesized as a response to relative stress. Since calcium is often involved in these processes, the relationship between silicon and calcium needs further clarification. As a structural component, silicon has a role in the reinforcement of cell walls and in reducing water loss through the deposition of silica in the leaf cuticle at the same time improving the overall water balance. It is curious how many of these effects might be found modest but when added together, the total effects of silicon are seen to be very important to plant growth, development and propagation, not forgetting post-harvest and human and animal nutrition. However, some care and attention needs to be made in consideration of more complex silicon-containing substances, what molecule (other than silicon) is doing what, where and how?

See presentation on the application of silicon in container plant production by Jonothan Franz, Greenhouse Produce Research, USDA/ARS, Toledo; Cornell_Poinsettia; Ornamentals_OFA_Bulletin.

Q5. Other information sources?

A fundamental reunion for the scientific community and members of the ISSAG is the International Conference on Silicon in Agriculture, held every three years. The next (8th) edition will be held at Baton Rouge, LA, USA, 2020.

The 7th International Conference on Silicon in Agriculture that took place at Bangalore, India, October 2017.  Congress proceedings pdf

Proceedings from the VI Silicon in Agriculture Conference 2014 held in Stockholm. Also Proceedings from V Silicon in Agriculture Conference, Beijing 2011. See also the Rutgers University pdf file on this conference and Si in Agriculture Conference South Africa 2008: Proceedings of the IV Silicon in Agriculture Conference pdf. Conference Brasil 2005: Proceedings of the III Silicon in Agriculture Conference

Bioactive silicon is beneficial to animal and human health and is commercially available as a food supplement, but that’s another story! For visitors interested in this aspect, the author could on request make available some further information.

See also: Silicon Review Prof Datnoff NewAg pdf / Silicon and plants James Locke pdf /Silicon and crop productivity Agripower pdfCan silicon based life exist pdf / Plant Nutrition, other beneficial elements, silicon.www.silicon_nutrition.info

Plant available bioactive silicon; helping plants to help themselves!

Edward Bent ©2013/2019 | HORTCOM

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