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Where to Find High-Quality Perlite and Vermiculite in South Africa

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Perlite and vermiculite can be used both as soil additives or as filter media. Due to their exceptional insulating properties, they are also often seen in the construction industry. 

Arguably, the most common use for perlite and vermiculite is in the agricultural and horticultural sectors. These minerals can retain up to four times their weight in water, and yet still aid in encouraging drainage. As a result of their porous nature, horticultural grade perlite and vermiculite help to maximise soil aeration. 

If you are keen to embrace the power of agricultural perlite and vermiculite, you will undoubtedly be looking for a perlite and vermiculite factory that specialises in perlite and vermiculite for sale in South Africa. Introducing Sun Silicates

South Africa’s Leading High-Capacity Perlite and Vermiculite Factory

Our perlite and vermiculite factory specialises in the manufacture of these high quality products for a variety of different sectors in South Africa. 

We sell perlite and vermiculite separately and we are also able to provide our customers with the opportunity to benefit from unique mixes of the two, as per their specifications and budget constraints. 

So, how can you be sure that our factory can supply you with world-class quality? For starters, Sun Silicates is ISO 9001:2015 compliant. Our high-quality perlite ore is imported from Turkish and Greek mines. The difference in quality is quite significant compared to other variants of perlite currently available on the market. It is characterised by low density while maintaining strength that ensures a dust-free product.

When it comes to processing our vermiculite, we effectively remove any foreign materials and also classify the product so that the coarser grades are dust-free. Our processes rely on natural gas to exfoliate the perlite and vermiculite, this, in turn, gives the growers the surety that no hydrocarbon deposits will find their way into the growing media, a problem that can have serious implications on plant health. The high temperature processes that are employed ensure a completely sterile product.

At our perlite and vermiculite factory, you can choose from a wide array of grades including coarse, medium, fine, superfine, and micron grades in line with your needs. 

In light of COVID-19 and the subsequent economic impact on the agriculture and construction industries, we are encouraging our customers to consider placing bulk orders and benefiting from the automatic discount thereof. Obviously, it is now more important than ever to cut costs! 

Get in touch today for more information or to place your order. 

Comparing Perlite Filter Media to Diatomaceous Earth-Based Filter Media

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Are you looking for the right filter media? If so, you will probably be debating whether to opt for perlite or diatomaceous earth. Here is what you need to know. 

Perlite as a Filter Media and When to Use it 

Perlite boasts the following characteristics:

  • Angular edges that trap suspended particles
  • Neutral pH and zero toxicity
  • Low wet cake density 

Perlite is available for purchase in a wide array of grades, as the product becomes finer it filter slower, but in turn the final filtrate becomes clearer. The finer the powder, the slower the filtration rate, thus making it suitable for use in a broad variety of filtration applications. Perlite excels when fast and course filtration is required.

Diatomaceous Earth-Based Filter Media and When to Use it 

Diatomaceous earth comes in a variety of grades that includes calcined and flux calcined grades. The flux calcined grades excel when used for fine filtration. For an equivalent particle size, diatomaceous earth filter media will filter faster than the equivalent perlite product. Having said that, it is still commonly employed as a filter media for swimming pools and in general water purification applications. It is used extensively for polishing filtration in both beer and wine processing. With the higher wet cake bulk density of diatomaceous earth, and the typically higher price, the product consumption and resultant cost of filtration will be dearer than when using perlite instead.

High-Grade Bulk Perlite for Sale in South Africa 

If you have decided to embrace the power of perlite as a filter media, you will need to purchase bulk perlite for sale in South Africa. Look no further than Sun Silicates.

We manufacture all the grades of perlite, including the horticultural, construction and filter grades. Currently, our perlite filter-aid is used in the filtration of wine, fruit juices, metal solutions and a variety of edible oils. 

Since Sun Silicates is supplying essential products into the food and agricultural industry, we can therefore supply for your needs even during the COVID-19 lockdown. Bulk orders come with a discount which effectively helps to cut costs. This could give your company the ‘edge’ in terms of recovering from the economic impact that the virus has had on most industries within South Africa. 

For more information, or to place your order, please be sure to get in touch with our team.

Perlite or Vermiculite for the Optimal Growth of Fruit and Vegetables

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If the goal is to optimise the growth of fruit and vegetables, you will be faced with a decision between growing in perlite or growing in vermiculite. These options promise to enhance air flow within the soil (Air filled porosity) and regulate moisture to help plants thrive. (water holding capacity) However, there are small differences to keep in mind too. Here are the benefits of each.

Why Use Perlite? 

Perlite works well as an additive to the soil, but it can also be used as a soil replacement. It can hold around three times its weight in water, and yet still aids in maximising drainage. It is extremely porous and therefore allows plenty of soil aeration, making it a top choice for growing succulents as well as fruit and vegetables that require fast and effective drainage. 

Why Use Vermiculite? 

Vermiculite can  hold up to four times its weight in water and is known to be able to trap moisture near plant roots. Unlike perlite which maximises drainage, vermiculite acts more like a sponge. The combination of the two substrates in your growing media ensures optimal air filled porosity and water holding capacity Vermiculite also has excellent cation exchange capabilities and hence absorbs nutrients form the irrigation system and then slowly releases it to the plants . Vermiculite also finds extensive use as a capping material for the germination of seeds.

Why Not Use Both? 

There is evidence to suggest that utilising a mix of both perlite and vermiculite is beneficial to the growth of fruit and vegetables. Here at Sun Silicates, due to the fact that we not only manufacture both bulk perlite and vermiculite, but we also have the ability to mix and bag in-house, we are in a unique position to supply premixed products that are custom-made to our customer’s requirements. Our laboratory facilities can also assist in optimising your growing media as we can measure the air-filled porosity and water holding capacity and thereby optimise it for your specific crop.

Bulk Perlite and Vermiculite From the Leading Manufacturer and Supplier in SA 

Now that you know the various benefits of growing in perlite and vermiculite, you will probably be in search of a reputable supplier. Here at Sun Silicates, we are bulk perlite and vermiculite suppliers that you can count on for quality. Contact us today to learn more. 

3 Common Soil Problems and How to Solve Them

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Is the growth in your garden being hampered as a result of soil problems? Then you are probably desperate to rectify the issues and to see your plants starting to thrive once again. Below is a list of three of the most common soil problems, which also explains how to solve them quickly and effectively by using products such as mulch, organic matter and horticultural perlite.

1. Lack of Fertility

One of the most likely reasons as to why your soil may not be quite as fertile as you had hoped is a high saline content. This is a big problem for people living near the ocean, but it can also affect gardens inland, especially in cases when the water table is  close to the soil’s surface. A possible way in which to remedy soil salinity is to add a layer of organic matter to the top of the soil. This should lead to a decreased need for water and a reduction in overall salinity. 

2. Nutrient Deficiency 

Look out for yellowing foliage, frequent insect infestations and poor growth as they can all be signs that your soil is lacking important nutrients. Resolve the problem by replenishing the soil’s nutrients with the help of a high-quality fertiliser as well as nutrient-rich organic matter, such as leaf mould or manure. 

3. Poor Drainage 

Poor drainage can result in excessive moisture that can lead to rotting roots, run-off and a reduction in topsoil. The easiest and most affordable way in which to maximise drainage is with the help of horticultural perlite. It allows for improved air flow throughout the soil and holds onto the perfect amount of water, all the while letting the excess drain away. 

Excesssive drainage /rapid drying of the soil is due to the lack of water holding capacity of your soil. This can be improved this  by adding coir/peat moss or horticultural vermiculite that absorbs large quantities of water and nutrients and slowly releases it to the plants.

Supplying World-Class Horticultural and Agricultural Perlite in Bulk 

Allow Sun Silicates to supply you with horticultural perlite and vermiculite for sale in South Africa. For more information about horticultural  perlite and vermiculite and how it can benefit you, do not hesitate to get in touch with our team. 

Perlite and vermiculite: the importance of growing media density

Gerbrand Haasbroek

When buying perlite and vermiculite in litres, the product with the lower density remains the better choice. Our latest blog post explains why.

Most people know that 1 liter of water weighs typically 1 kg. This fact is sometimes confused when dealing with products that has significantly lower density as is the case with growing media. People tend to buy a “bag” or per Kg not realising that there could be a significant difference in the volume of the product that you buy.

Formulation

The relationship between mass, volume and density is the simple formulation of:

Density = Mass / Volume

P = M/V

From this equation, you can generate a formula to calculate any of the other unknowns, as long as you have the other two know values i.e.

M = P X V

V = M/P

The standard unit for density is Kg/cubic meters. In many instances, people talk of densities in terms of grams per litre as it sounds “better” or beacuse, in the lab, you would typically fill a one-liter flask and weigh the material in grams.

An example of this will be Perlite that weighs 100 kg/cubic meter i.e. the density is 0.1. Instead of using this, people will call this density “100” i.e. 100 grams per litre.

Why is density important in perlite and vermiculite? 

The following are a few reasons why density is important:

  1.   In a horticultural environment, you typically want to fill a container such as a planter. The lower the growing media density ,the more volume of product you will get per kg you have bought.
  2.   The lower the density, the more air is in the medium. This allows for the following:
  3.   Improved drainage
  4.   Improved insulation in cold climates
  5.   More air-filled porosity that is required for the roots to grow and transpire.
  6.   The lighter the planter will be to move around.
  7.   When the manufacturer exfoliates the perlite or vermiculite, he starts off with a dense ore that is then exfoliated to the final low-density product. The lighter the product, the smaller quantity of initial ore is used to manufacture the final product. This leads to lower input cost, which should translate into a cheaper product for the customer. The less ore the supplier uses, the less energy he needs to produce a litre of product. Once again, this drives  the cost of the final product down. Energy cost is a major component of the manufacturing expense.
  8.   When the growing media breaks down during handling/manufacturing, the small particles find its way in between the larger particles, this, in turn, increases the packing density of the media. Fine particles are detrimental in a growing media as it reduces the air-filled porosity that in turn affect root growth. It therefore stands to reason that buying in litres, the product with the lower density remains the better choice.
  9.   There is a direct correlation between density and the strength of the particles, therefore it is also important to note that very light material might not be as good as it will need to be handled carefully to prevent unwanted breakdown. 

What is a typical density of a growing media for perlite and vermiculite? 

The density of the final growing media is determined by the exfoliation process as well as the original ore quality. Growing media with density ranging from 70 to 120 g/liter is typical.

Need more information about perlite or vermiculite? Then contact us today.

How to Use Perlite in Growing Media

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You might have heard all about the benefits of horticultural perlite, such as its ease of use, sustainability, affordability and convenience. If so, you may be wondering how to put it to good use in your residential, commercial or agricultural gardens. Here is what you need to know. 

Why Should I Consider Growing in Perlite?

Horticultural  perlite is an amorphous volcanic glass that effectively stores moisture and nutrients for plants. Perlite only retains a complementary amount of moisture based on the rate at which the plant absorbs it, all the while allowing any excess to drain away. Along with these benefits, perlite is a great choice for gardeners and farmers because it is clean, lightweight, sterile and environmentally friendly.

How to Start Growing in Perlite

The first step is choosing what type of perlite to use. It is available in three different , namely coarse/large, medium, and fine. 

  • Coarse Agricultural Perlite

Due to the fact that coarse horticultural perlite has the highest level of porosity, it maximises drainage and allows for better airflow throughout the soil. For this reason, coarse perlite is often a great choice for both residential and commercial gardens. 

  • Medium Perlite

This grade is typically used in the construction industry, however it can also be used when you are propagating seedlings in small trays. It can also be used in pots or bags on its own, for growing tomatoes, cucumbers and peppers.

  • Fine Perlite

The fine perlite entrains more water than the coarser grades and is used in a similar applications as the medium perlite as well as when rapid root production is required. As such, you will often find it in rooting cuttings and seed-starting mixes.

Finally, you can also utilise horticultural  perlite in hydroponics. 

We Manufacture High-Quality Horticultural Perlite 

There are many reasons why you should consider Sun Silicates as your trusted horticultural perlite supplier. For example, due to the fact that we are the only local manufacturer of both perlite and vermiculite. Furthermore we are in a unique position to supply premixed products that are custom-made to our customer’s requirements. For more information about our horticultural perlite for sale, please do not hesitate to get in touch with our team.

The Role of Perlite in Hydroponic Culture

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Perlite has been utilised successfully  in a wide range of horticultural applications, and its role in hydroponic culture is no exception. There have been a number of studies that have demonstrated the superiority of perlite in comparison to numerous other substrates  used in hydroponic culture. 

Benefits of Perlite in Hydroponics

One of the benefits of using perlite in  hydroponics is the fact that it has been proven to drastically increase crop yields. It  also works better as a rooting medium when compared to another popular choice within hydroponic culture, namely rockwool. Perlite boasts maximum capillarity and, as a result, has the ability to maintain a constant supply of water and nutrients when the plant container is placed in a shallow reservoir of a solution rich in moisture and nutrients. The perlite effortlessly draws the solution up from the reservoir, complementing the rate at which the plants naturally absorb water. 

Perlite is also the ‘greener’ choice from a reusability perspective. Contrary to rockwool, it is able to retain its superior water and air balance for a number of years as long as treated correctly. It can be reused over the course of a number of growing seasons, following which it can be used as part of a nutritious potting mix or to aid in conditioning the soil. Disposing of rockwool may be problematic as it is not a natural mineral.

Finally, it is also known that perlite is especially straightforward to manage. And, it is extremely affordable, particularly when bulk perlite is purchased from a reputable supplier.

Buy Bulk Perlite for Hydroponics in South Africa 

Are you looking to embrace perlite hydroponics in South Africa? If so, you will require a supplier that you can trust for quality. Look no further than Sun Silicates. We focus on supplying high-tech products to, amongst others, the chemical, metallurgical, construction and agricultural sectors. For more information about investing in bulk perlite for hydroponics, please do not hesitate to get in touch

The importance of perlite and its size distribution in growing media

Gerbrand Haasbroek

DON’T JUST BLEND IN…

Understanding the purpose that each growing medium serves is the first step to selecting a unique blend for your needs.

Air, water and nutrients are the three basic requirements of plants and finding a balance between these three will ensure you promote strong root growth and healthy plants.

Photosynthesis is another key process in plant growth, however the reactions and interactions taking place below the surface of the growing medium is often neglected. The roots and microorganisms within a growing medium absorb oxygen and release carbon dioxide. As the carbon dioxide fills the growing medium, it must be replaced by oxygen so that the roots are protected from carbon dioxide poisoning and can partake in root respiration.

Oxygen traverses into a growing medium through the process of diffusion. The oxygen moves from an area of high concentration, which in this case would be the environment, to an area of low oxygen concentration. Many growing mediums become waterlogged during irrigation which either entraps the carbon dioxide within the medium or the water surrounds the entire root system thereby suppressing the presence of oxygen available to the roots.

The importance of providing water to a plant is affected by the water supplied and the water drained.  Finding and maintaining a balance between these two factors will be key to creating the most favourable environment for your plants. The ability to hold water in your medium is largely dependent on the material type and the particle size distribution of your medium.

A BLEND IS BEST…

Bark, Peat and Coir are the most common growing media as they are able to retain high levels of water. Bark mediums can have up to 40 % pore space which absorbs and stores water whilst coir has a fine pore structure which is ideal for high water holding capacity. Peat and peat mosses are comprised of partially decomposed plants which are able to retain their cellular structure which ensures a high water-holding capacity.

The ability of a medium to hold water stems from the pore size. A smaller pore, known as a micropore, has the ability to store water due to capillary forces which in this case are stronger than the gravitational pull on the water.  The presence of these micropores and their quantity influences the measure of the water holding capacity of a growing medium. In addition to micropores, the formation of macropores within a growing medium is equally important.

Macropores provide pathways for oxygen to move through the medium to aerate the root system and to improve drainage.  The majority of growing medium blends containing bark, peat and/or coir have high water holding capacities, however drainage and structure within the medium may become problematic over time which will adversely impact the plant’s root system.

Good structure in a growing medium requires a balance between macro and micropores to provide required levels of aeration whilst, at the same time, maintaining an acceptable water holding capacity. As growing media age, the macropores tend to collapse as the organic materials decompose and the structure of the media shift.  The air-filled porosity will decrease as there are fewer pathways for diffusion and the water holding capacity will increase as the drainage of the medium is clogged.

IMPROVING DRAINAGE AND AIR-FILLED POROSITY

Perlite is ideal in growing media blends as it provides a larger particle size and a structure that doesn’t decompose over time. Horticultural grade perlite is inert, contains a porous structure and is typically sized between 1-3 mm. Blending perlite with other growing media can significantly increase the air-filled porosity, whilst still maintaining the water-holding capacity.

The perlite particles are not uniform in shape and therefore “break” the uniformity of the material.  These “breaks” allow for the formation of macropores which create the channels in a blend. The particle size of perlite is of utmost importance as a larger particle size creates the macropores however a particle finer than 1 mm can contribute to clogging the medium which is counterproductive in this instance.

As an inert material, perlite will not degrade over time in a growing medium. The effect of compaction due to irrigation is also greatly reduced because the perlite structure is porous and therefore has the ability to absorb and release excess water without altering the shape or size of the particle.  Perlite has the ability to transform the behaviour of a growing media blend and provide the most suitable environment for both healthy root and plant growth.

 

 

 

Considerations when choosing an optimal growing media

Gerbrand Haasbroek

Choosing the optimal growing media requires special consideration, because it is much more than just an anchor for the plant: it can be crucial to the successful growth of the plant.

Dozens of different ingredients are used in varying combinations to create homemade or commercial growing media blends. By understanding the functions of growing media, you can take advantage of the unique characteristics of each media allowing you to tailor a blend which will provide the ideal growing conditions for your specific needs.

FUNCTIONS OF GROWING MEDIA

Physical Support
The growing medium must be porous yet provide physical support. Young plants are fragile and must remain upright so that they can photosynthesize and grow.

Aeration
Plant roots need a steady supply of oxygen to convert the photosynthate from the leaves into energy so that the roots can grow and take up water and mineral nutrients. The by-product of this respiration is carbon dioxide that must be dispersed into the atmosphere to prevent the build-up of toxic concentrations within the root zone. This gas exchange occurs in the large pores (macropores) or air spaces in the growing medium.
Water
Plants use a tremendous amount of water for growth and development, and this water supply must be provided by the growing medium. Growing media are formulated so that they can hold water in the small pores (micropores) between their particles. Many growing mediums contain a high percentage of organic matter such as peat moss and compost because these materials have internal spaces that can hold water like a sponge. Therefore, growing media must have adequate porosity to absorb and store the large amounts of water needed by the growing plant.
Supply of Mineral Nutrients
Most of the essential mineral nutrients that plants need for rapid growth must be obtained through the roots from the growing medium. Most mineral nutrients are electrically charged ions. Positively charged ions (cations) include ammonium (NH4+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+). These cations are attracted to negatively charged sites on growing medium particles up to the point when the roots extract the cations. The capacity of a growing medium to adsorb these cations is referred to as cation exchange capacity (CEC). Different media components vary considerably in their CEC, but peat moss, vermiculite, and compost have a high CEC value, which explains their popularity in growing media. A growing media which can readily exchange cations to the plants roots allows the greatest opportunity for nutrient absorption.

Seedlings sprouting (Pixabay)

MOST IMPORTANT FACTORS WHEN CHOOSING GROWING MEDIA

Chemical properties:

pH

The pH of growing medium is a measure of its relative acidity or alkalinity. pH values range from 0 to 14; those below 7 are acidic and those above 7 are alkaline. Most native plants tend to grow best at pH levels between 5.5 and 6.2, although some species are tolerant of higher or lower pH levels. The main effect of pH on plant growth is its control on nutrient availability. The availability of micronutrients, such as iron, is even more affected by pH. Iron chlorosis, caused by high pH, is one of the most common nutrient deficiencies of nursery stock. Exceptionally high or low pH levels also affect the abundance of pathogens and beneficial microorganisms.

Photo showing Fe deficiency in a plant (pH = 7.3) (Lindi Grobler)

 

Photo showing Mn toxicity in a plant (pH = 4.6) (Lindi Grobler)

How do I increase the pH?

Addition of a liming material will raise the pH of your medium. This will however entail a number of additional controls such as quantity of addition, timing of application, grade of liming agent and the frequency of dosing. To find the optimum some time and research will be required on the specific blend and whether the mix is a potting blend or in soil.

How do I reduce the pH?

Acidifying growing media is often considered as a complex process as the additives and dosing is of extreme importance. Generally, to reduce the pH, sulphur is dosed. Due to availability and cost iron (ferrous) sulphate, phosphoric acid solution may also be used. The toxic side effects must be taken into consideration prior to dosing and the acidification of soils is only recommended when there is a low percentage of lime present due to the economic implications.

The pH affects the nutrient solubility and availability. A low pH causes micro nutrient toxicity, and a high pH causes nutrient deficiency.

Electrical Conductivity (EC)

EC is the measure of total dissolved salts in a solution, this influences a plant’s ability to absorb water. In horticultural applications, monitoring salinity helps manage the effects of soluble salts on plant growth. EC is a meaningful indicator of water quality, soil salinity and fertilizer concentration.

Photo showing the importance of electrical conductivity (EC) in plants (Lindi Grobler)

Cation Exchange Capacity (CEC)

CEC refers to the ability of a growing medium to hold positively charged ions. Because most growing media are inherently infertile, CEC is a very important consideration. In the growing medium, plant roots exchange excess charged ions for charged nutrient ions, and then these nutrients are transported to the foliage, where they are used for growth and development. Because the CEC of a growing medium reflects its nutrient storage capacity, it provides an indication of how often fertilization will be required.

Nutrients

Nitrogen

Nitrogen is such a vital nutrient because it is a major component of chlorophyll, the compound through which plants use sunlight energy to produce sugars from water and carbon dioxide (i.e., photosynthesis). It is also a major component of amino acids which are the building blocks of proteins

Without proteins, plants wither and die. Some proteins act as structural units in plant cells while others act as enzymes which are essential in many biochemical reactions on which life is based. Nitrogen is a component of energy-transfer compounds, such as ATP (adenosine triphosphate). ATP allows cells to conserve and use the energy released in metabolism. Finally, nitrogen is a significant component of nucleic acids such as DNA, the genetic material that allows cells (and eventually whole plants) to grow and reproduce. Without nitrogen, there would be no life as we know it.

Magnesium

Magnesium is an essential plant nutrient that has a wide range of key roles in many plant functions. One of magnesium’s well-known roles is in the photosynthesis process, as it is a building block of Chlorophyll, which makes leaves appear green

Potassium

Potassium is an essential plant nutrient and is required in large amounts for proper growth and reproduction of plants. Potassium is considered second only to nitrogen, when it comes to nutrients required by plants, and is commonly considered as the “quality nutrient.”

It affects the plant shape, size, colour, taste and other measurements attributed to healthy produce.

Plants absorb potassium in its ionic form, K+.

Potassium has many different roles in plants:

  • In Photosynthesis, potassium regulates the opening and closing of stomata, and therefore regulates CO2
  • Potassium triggers activation of enzymes and is essential for production of Adenosine Triphosphate (ATP). ATP is an important energy source for many chemical processes taking place in during plant growth and respiration.
  • Potassium plays a major role in the regulation of water in plants (osmo-regulation). Both uptake of water through plant roots and its loss through the stomata are affected by potassium.
  • Protein and starch synthesis in plants require potassium as well. Potassium is essential at almost every step of the protein synthesis. In starch synthesis, the enzyme responsible for the process is activated by potassium.

Potassium deficiency might cause abnormalities in plants, usually the symptoms are growth related.

Cholrosis – scorching of plant leaves, with yellowing of the margins of the leaf. This is one of the first symptoms of Potassium deficiency. Symptoms appear on middle and lower leaves.

Slow or Stunted growth – as potassium is an important growth catalyst in plants, potassium deficient plants will have slower or stunted growth.

Poor resistance to temperature changes and to drought – Poor potassium uptake will result in less water circulation in the plant. This will make the plant more susceptible to drought and temperature changes.

Defoliation – left unattended, potassium deficiency in plants results in plants losing their leaves sooner than they should. This process might become even faster if the plant is exposed to drought or high temperatures. Leaves turn yellow, then brown and eventually fall off one by one.

Other symptoms of Potassium deficiency:

  • Poor resistance to pests
  • Weak and unhealthy roots
  • Uneven ripening of fruits

Manganese

Manganese is one of nine essential nutrients that plants require for growth. Many processes are dependent on this nutrient, including chloroplast formation, photosynthesis, nitrogen metabolism and synthesis of some enzymes. The role of manganese in plants is extremely crucial. Deficiency, which is common in soils that have neutral to high pH or a substantial deal of organic matter, can have a significant effect on the health and growth of plants.
Physical Properties

Medium texture & structure

The texture of growing media can either be defined as “fine” or “coarse”, and this is determined by the particle size distribution of the growing medium. When one is familiar with the texture of the growing media, it allows speculation as to other properties of the growing media, for example, fine growing media has a difficult water infiltration rate, and is easily waterlogged, where a course growing media has rapid infiltration, rapid drainage and a lowered water holding capacity.)

The structure of the media is determined by the particle size distribution, which is the percentage fine or course particles in a growing media.

Aeration of medium

The air-filled porosity of the media is the sizes of the pores in the media or “openness” of the media. The smaller pores filled with water and the larges pores are filled by air. The water that can be found in the largest of the smallest pores is available to the plant, and the water found in the tiniest pores are unavailable to the plant.

The proportion of air to readily available water is equal to the proportion of pores of different sizes. The larger pores the growing media has, the more air it holds. Many small pores are equivalent to a high ability to hold water.

Air filled porosity should increase as the height of a container increases, the air porosity will also determine the irrigation frequency and quantity. The importance of air filled porosity correlates to the respiration process which occurs at the root structure of the plant as well as the incidence of waterlogging. Providing sufficient aeration and reducing the likelihood of waterlogging encourages healthy root and stem growth avoiding root rot and stunted plant growth.

Water holding capacity

The air-filled porosity determines the infiltration rate. One must have a balance between air filled porosity and available water, and the readily available water should be as high as possible without significantly impacting the supply of air to the root system.

Each medium release water according to the suction supplied by the roots of the plants. Therefore, a growing medium blend must accommodate the amount of water required by the plant as well as the frequency of irrigation. Selection of a suitable growing medium may reduce the frequency of irrigation required due to the mediums ability to store and supply water which may have been otherwise lost to evaporation and drainage.

DIFFERENT KINDS OF GROWING MEDIA

Peat moss

Peat moss is a partly decomposed material containing remains of plants growing in swampy areas and is usually very acidic.

Sphagnum peat moss is currently the most common organic component of growing media. Although types of peat moss may appear similar, they can have very different physical and chemical properties.

Saw dust / saw shavings

Raw sawdust, with its high C:N, can negatively affect nutrient availability, especially nitrogen but its properties can be improved with composting. Additionally, because of the inherent differences in chemical properties between different woods, the suitability of sawdust as an organic growing media component is extremely variable. Some species produce sawdust with phytotoxic effects. Only consider using sawdust from sawmills because other wood residues, such as those from treated boards, may contain preservatives or harmful chemicals. Sawdust from coastal sawmills can contain high levels of salts, so all potential sources need to be tested before general use in the nursery.

Coir/Coir fibre/Coco peat

A by-product of processing coconut husks is known as coir dust, coco peat, or simply coir. This material has proven to be an excellent organic component for container growing media and is readily available in some tropical locales. Coconut coir has many desirable qualities: high water-holding capacity; excellent drainage; absence of weeds and pathogens; physical resiliency (withstands compression of baling better than Sphagnum peat); slow decomposition; easy wettability; and acceptable levels of pH, cation exchange capacity, and electrical conductivity. Coir is very similar to peat in appearance and structure, and, like peat, physical and chemical properties of coir can vary widely from source to source. Coir is low in nitrogen, calcium, and magnesium but can be relatively high in phosphorus and potassium. Excess salinity and phenolic compounds in coir can be a problem in areas with inadequate quality control. In addition, some coir sources have reportedly contained chlorides at levels toxic to many plants. Thus, it is very important that salts and other compounds are thoroughly leached with fresh water before use.

Plants growing in coir (Lindi Grobler)

Perlite

Perlite is a siliceous material of volcanic origin, and supplies no nutrition to plants. Perlite particles have a unique closed-cell structure so that water adheres only to their surface; they do not absorb water as peat moss or vermiculite do. Therefore, growing media containing perlite are well drained and lightweight. Perlite is also rigid and does not compress easily, which promotes good porosity. Because of the high temperatures at which it is processed, perlite is completely sterile. It is essentially infertile, has a minimal CEC, and has a neutral pH. Perlite is typically included to increase aeration, and commercial mixes contain no more than 10 to 30 percent perlite.

Perlite used as a growing media

Vermiculite

Vermiculite is a common component and is a hydrated aluminium-iron-magnesium silicate material that has an accordion-like structure. Vermiculite has a very low bulk density and an extremely high water-holding capacity, approximately five times its weight. This material also has a neutral pH, a high CEC, and contains small amounts of potassium and magnesium. Vermiculite deteriorates when wet as the particles collapses and this should be accounted for when selecting growing media blends.

Potatoes growing in SunPerl Vermiculite (Sun Silicates)

Pumice

Pumice is a type of volcanic rock consisting of mostly silicon dioxide and aluminium oxide with small amounts of iron, calcium, magnesium, and sodium. The porous nature of pumice particles improves aeration porosity but also retains water within the pores. Pumice is the most durable of the inorganic ingredients and so resists compaction. Pumice has a neutral pH without CEC and therefore does not interfere with the availability of nutrients.

One could either use these media on their own or combine the media to create a mix.

WHAT INFLUENCES MY CHOICE WHEN CHOOSING A GROWING MEDIA?

The 2 most important factors when choosing a growing media are

The pH

When managing the pH, it is important to know the media pH one started with. Also, the changes in the pH must be monitored as the plants develop (the pH provides an indication on the availability of nutrients).

The container used to plant in

When managing the containers, one must choose containers according to the environment, water quality and the growing media that will be used. Factors that must be considered is the depth of the container, volume of the container, shape of the container, width of the container and the draining hole.

Using containers that are too small

Soil serves as the main source of nutrients for any plant. With less soil in a smaller container, there are fewer nutrients available for the plant’s root system. A container that is too small can constrict the plant’s roots, especially plants with big roots. The roots can get packed in without having enough room to spread out. If this happens, the plant’s growth may slow down. Plants may also be tipping over because of the extra weight in comparison to the container.

One way to know if your plant needs a bigger container is to look for roots poking out of the drainage holes in the bottom. A container that is too small also won’t hold enough water to support the plant. And the soil dries out quickly. You might notice that the plant shows signs of drought sooner if the container is too small.

Using containers that are too large

It may seem like going with an over sized container is better so you can avoid the crowded root situation. But a container that’s too big for your plant can also have negative effects on its growth. A container that is too large for a plant can hold too much water in the soil or take too long to dry out, which can lead to mold growth, rot and root diseases. Too large of a container can also make it difficult to keep the soil firmly packed around the plant’s roots.

How to choose a proper size container

The best container for each plant depends on the size of the plant and its needs. A container should allow the plant’s root system to spread out somewhat and drain well. This means that the container should not be soaked after it is watered because the water should drain out the bottom. If your plant is currently in a container that’s too small, move it to a container that’s about 5 cm to 10 cm larger in diameter.

Choosing the right size container is crucial when planting as it leads to the successful growth of the plant

 

For more information regarding growing media, please visit www.sunsilicates.co.za, of contact us at 011 824 4600 with any questions or queries.

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Sun Silicates (Pty) Ltd focuses on supplying high-tech consumable products to the chemical, metallurgical and agricultural industries. The company is customer and performance focused and we ensure our customers of quality products at competitive pricing.

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