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Potassium sulphate crystals

Sulphate of Potash ( SOP ) : The Gentle Fertilizer

Morvarid Aras Baran Co is the biggest producer chemical & agriculture fertilizer in Iran and business unit produces and markets a full range of sulphate of potash (SOP) fertilizers. We have more than 12 years’ experience in SOP production and are the Iran’s first largest supplier of SOP products. Our SoluPotasse grade is in water soluble SOP fertilizers and we have recently introduced MABCO, a special fast-dissolving grade of SOP for foliar application.

Sulphate of potassium (SOP), or potassium sulphate (K2SO4), is the world’s most popular low-chloride fertilizer. It combines the essential nutrients potassium (K) and sulphur (S) in an optimal form which is readily available to plants. A 53% K2O (42% K) and 52% SO4 (18% S) content enables SOP to supply a very high concentration of nutrients.

SOP increases both the yield and quality of high value crops, particularly fruit, vegetables and tobacco.

It improves the crop’s nutritional value, taste and appearance (size, color and scent) as well as its resistance to deterioration during transport and storage and its suitability for industrial processing.

SOP also helps to improve a crop’s resistance to drought, frost, insects and disease.

The Importance Of  Potassium To Plants

Potassium has two roles in the functioning of plant cells.

First, it has an irreplaceable part to play in the activation of enzymes which are fundamental to metabolic processes, especially the production of proteins and sugars. Only small amounts of potassium are required for this biochemical function.

Second, potassium is the “plant-preferred” ion for maintaining the water content and hence the turgor (rigidity) of each cell, a biophysical role.

A large concentration of potassium in the cell sap (i.e. the liquid inside the cell) creates conditions that cause water to move into the cell (osmosis) through the porous cell wall.


Turgid cells maintain the leaf’s vigor so that

Photosynthesis proceeds efficiently.



Osmosis in plants

Osmosis is defined as the passage of water from a region where the concentration of salts is low through a semi-permeable membrane to a region where the concentration of salts is higher. In plants, water moves from cells with a low, to those with a higher, concentration of salts.

This process is responsible for the movement of water within the plant and also the uptake of water from the soil by the roots. These conditions that lead to water movement are termed the ‘osmotic potential’.

 Much of the potassium in the plant is in the liquid within the cell and its presence increases the salt

Concentration and thus controls the movement of water.

When plants take up water by osmosis their cells become gradually more turgid (swollen) until no more water can enter the cell. Turgidity is very important to plants because it maintains the rigid structure of most annual crops which do not have a woody structure of trunks and branches.

In all plants, turgid leaves have a large surface area and this optimizes the process of photosynthesis in the green chloroplasts in the cells.

 Photosynthesis is the process by which plants harvest the energy of sunlight to produce sugars.

These sugars contain carbon derived from the carbon dioxide in the air that has entered the leaf through the stomata, tiny openings mainly on the underside of the leaf.

These tiny openings are surrounded by “guard cells” and it is only while they are turgid that the stomata remain open and carbon dioxide can pass through into the leaf. But most of the water transpired by the plant is lost through the stomata when they are open.

 Thus, if there is a water deficit, the plant needs to close the stomata to conserve water. The plant controls the opening /closing of the stomata by regulating the concentration of potassium in the guard cells.

A large concentration of potassium ensures turgid cells and open stomata.

 When the potassium in the guard cells is lowered, they become limp and the stomata close.

A high osmotic potential in plant cells is also needed to ensure the movement through the plant of nutrients required for growth, and the sugars produced by photosynthesis, for example, the transport of sugar to grains, beet roots, tubers, and fruit.

By maintaining the salt concentration in the cell sap, potassium helps plants combat the adverse effects of drought and frost damage and insect and disease attack.




Virtually chloride-free, SOP is the best nutrient source for chloride-sensitive crops and intensive cropping systems.

Compared to other sources of potassium such as MOP (muriate of potash) and NOP (nitrate of potash), SOP has a very low salinity index making it the preferred potash fertilizer in soils at risk from salinity. These features make SOP the most effective fertilizer in many parts of the world and the most environmentally-friendly.

Foliar application of soluble SOP is an efficient way to rapidly correct a potassium deficiency in crops.

Complimentary SOP foliar sprays not only deliver an immediate potash boost but also improve the uptake of potassium and other nutrients via the crop’s root system, enhancing yield and quality.


The need to increase fertilizer efficiency yet meet environmental concerns means that growers demand the ability to apply an exact, uniform dose of fertilizer whenever a crop needs it.

GranuPotasse is our granular grade of SOP ideal for bulk blending with a wide range of fertilizers, as well

as for direct application. Its granules are compacted to extreme hardness so they can be handled and

mixed without damage.

 To facilitate use, GranuPotasse is also treated to be dust-free.

Standard SOP powder is an ideal raw material for manufacturing high quality compound fertilizers for

fruit and vegetables. It can also be used as a straight fertilizer for soil application.

For full product characteristics, please consult the specification sheets on our website:




Role Potassium (K) In Plant Growth:

Potassium (K) is an essential nutrient for plant growth. Because large amounts are absorbed from the root zone in the production of most agronomic crops, it is classified as a macronutrient. Potassium (K) is associated with movement of water, nutrients, and carbohydrates in plant tissue.



The Adventage Of Potassium Sulphate Fertilizer :

Sulphate of Potash (SOP) has Sulphur  and it is essential in the structural and enzymatic components in plants. Sulphur is a key component of some essential amino acids and is needed for protein synthesis. Chlorophyll synthesis also requires S.

Sulphur is not readily translocated within plants, so all plants need a continuous supply of sulphur from emergence to crop maturity. Therefore, in S-deficient plants, older leaves may appear more healthy, while newer leaves and tissue may have stunted growth and a lighter green or even yellow appearance.

A sulphur deficiency at any growth stage can result in reduced crop growth and yield. Adequate S results in rapid crop growth and earlier maturity.

Potassium sulfate granulation

Guaranteed  Elements :

  K2o    :   50%

S           :      17/5 %

CL        :      maximum 2/5%

Indications   and consumption :

Soil  application : mixed one kg sulfate in the garden with other fertilizers needed in the bottlom of drilled holes , for planting sapling then covered it with soil then action is to cultivate seedling . 

Young seedlings :

Fruitless tree :

Time and route of administration :

Tree :  in  the winter mixed it with soil , in the outer half of shading to a depth of active roots mixed it with soil.

Plant  crop  :  to determine the exact amount of fertilizer referring to the analysis of soil and water  is  necessary.

Instructions  :Use with  other  fertilizer  before  plowing.

Important  notice : to determine the exact amount of fertilizer referring to the analysis of soil and water  is  necessary.