Potassium Polyacrylate – Superabsorbent Polymer for Plant


    Potassium polyacrylate is a kind of superabsorbent polymer. So, what is a superabsorbent polymer (SAP)?

    the strongest water-absorbent material in the world
    NamePotassium Polyacrylate
    CAS Number25608-12-02
    ECHA InfoCard100.118.160
    EC Number607-755-0
    CompTox Dashboard (EPA)DTXSID801011074
    Chemical Formula[−CH2−CH(CO2K)−]n or (C3H3KO2)n

    As an advanced physical absorbent material, SAP can quickly absorb a large amount of water and lock it firmly. When the water absorption reaches saturation, it changes from a powder or granular state to a hydrogel state.

    Generally, the water absorption capacity of SAP can reach hundreds of times its own. For special purposes, it can reach thousands of times.

    As an eco-friendly material, it is totally non-toxic, harmless, and nonpolluting.

    What is potassium polyacrylate?

    Potassium polyacrylate is a type of SAPs for plants as a water-retaining agent.

    Compared with ordinary SAP, agriculture grade SAP (potassium polyacrylate) has undergone post-processing in the production process (such as grafting), which makes it have the unique advantages of being specially used in agriculture:

    • Change the cation of the polymer from sodium ion to potassium ion. This not only eliminates the risk of soil salinization caused by sodium ions, but also fertilizes the soil with potassium ions after decomposition.
    • Improve water absorption capacity in soil: Significantly increase the absorption capacity of high-concentration ionic liquid (soil leachate) under soil pressure.
    • Extend the decomposition time in nature.
      • Ordinary SAP will melt and decompose to form a gel within a month or so after absorbing water.
      • Agricultural SAP (potassium polyacrylate) can repeatedly absorb and release water in the soil for tens of months.
    • After natural degradation, it will be reduced to ammonium nitrogen, water and a small amount of potassium ions, effectively improving the soil.
    Potassium polyacrylate - Water retaining agent
    Water retaining agent

    These advantages make it like a “mini reservoir”: it absorbs enough water and stores it during the rainy season or during irrigation, and then continuously provides water to the plants when the soil is dry.

    As a result, it brings many intuitive benefits to agriculture such as:

    • Improves seed germination and emergence, giving plants an early, healthy start.
    • slow sustained release fertilizer.
    • Improve soil water holding capacity (sand land can be increased by 85%) and save irrigation water.
    • Increase crop and fruit production. For melon cultivation in California, the yield has increased by 70%.

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    How does it work?

    Agriculture grade SAP consists of a set of polymeric chains that are parallel to each other and regularly linked to each other by cross-linking agents, thus forming a network.

    When water comes into contact with one of these chains, it is drawn into the molecule by osmosis. Water rapidly migrates into the interior of the polymer network where it is stored. That’s how SAP powder turns to water gel.

    As this water gel’s absorption ability is bigger than soil but less than roots of plants, the absorbed water by SAP will be released to plants when it is dry.

    Tips: the specific retention of agriculture SAP is 1.3-1.4 MPa and the specific retention of roots is about 1.6-1.7 MPa.

    Test the Potassium Polyacrylate

    Water Holding Capacity Test

    Test objective

    Performance Study in varying soil classifications (test the water retention capacity of SAP in different soils)

    Sample volumes Used

    Soil: 500ml; Water: 750ml; SAP: 5 gram;

    Test 01 – Soil Type: 100% Sand

    Test itemControl Group (without SAP) – 762gTest Group (with SAP) – 768g
    Water passing (ml)425150
    Water retaining (ml)325600
    % retaining43.380
    % increase85

    Test 02 – Soil Type: 37% Sand + 40% Silt + 25% Clay

    Test itemControl Group (without SAP) – 615gTest Group (with SAP) – 626g
    Water passing (ml)275100
    Water retaining (ml)475650
    % retaining63.386
    % increase36

    Test 03 – Soil Type: 30% Sand + 48% Silt + 22% Clay

    Test itemControl Group (without SAP) – 407gTest Group (with SAP) – 400g
    Water passing (ml)352200
    Water retaining (ml)398550
    % retaining53.173.3
    % increase38

    Laboratory Test ( wilting point )

    How to use potassium polyacrylate?

    For perennial plants

    The main method of using perennial plants (fruit, tea, forest, banana, mulberry, cane, medicinal materials, bamboo shoots) is “dipping root + base application”.

    “Dipping root + base application” refers to dipping seedling roots with hydrogel (potassium polyacrylate + water) mixed with fine-grained water-retaining agent, and adding the large-grained gel agent after water absorption when backfilling the planting hole.

    • Dipping the roots can prevent the seedlings from dehydrating during planting.
    • The potassium polyacrylate hydrogel base application can provide the closest and most easily absorbed effective water source during the critical period of seedling rooting, shortening the slow seedling period.


    Root dip

    Mix potassium polyacrylate water retaining agent (80~100 mesh) with fine soil in a ratio of 1:5~1:10 and put them into a large non-metallic container.

    In order for the water-retaining agent to have enough time to absorb water, add about 100-150 times the weight of potassium polyacrylate water (rooting powder can be added at the same time) 6-20 hours before dipping the roots, mix and stir to form a gel or colloidal mud .

    Then it can be used for dipping the roots of seedlings for afforestation. When dipping the roots of seedlings, single or multiple plants can be used, and no more than 50 plants can be used. It is necessary to ensure that the roots of seedlings are completely immersed in the gel or gelatinous mud to fully dip the roots.

    Cuttage seedlings in seedbeds

    A. Direct use

    • Mix 5~15g of potassium polyacrylate particles per square meter on the seedbed evenly.
    • Level the seedbed and cover it with a thin layer of fine soil.
    • Dip the base of the branch into the root, then cut it on the seedbed, and water it.

    B. Stir with water to form a hydrogel before use

    • Mix the gel agent accounting for 1/5~3/5 of the total mass of the matrix soil into the matrix soil on the seedbed and mix evenly.
    • Level the seedbed and cover it with a thin layer of fine soil.
    • Dip the base of the branch into the root, then place the cutting on the seedbed, and water it.

    Culture bag seedling

    A. Direct use

    • Add 0.1%~0.3% dry product of water-retaining agent into the culture medium, mix it evenly, and pack it into bags.
    • Water immediately.
    • Sowing, budding, transplanting and raising seedlings.

    B. Cell building

    • Add the gel agent that accounts for 1/5~3/5 of the total mass of the culture medium into the culture medium, mix it evenly, and pack it into bags.
    • Water regularly.
    • Sowing, budding, transplanting seedlings.

    Base application

    A. Direct use

    • Sprinkle potassium polyacrylate particles directly into the dug holes.
    • Mix well with the fine soil at the bottom of the hole.
    • Then move the rooted saplings, cover with soil in a concave shape (so as to collect water), and immediately water enough water.

    B. Stir with water to form a hydrogel before use

    • The gel is applied into the dug hole, and then fully mixed with the fine soil at the bottom of the hole.
    • Then move the rooted saplings and cover them in a concave shape (in order to collect rainwater).
    • Immediately pour the root water again.

    Tree topdressing

    Ribbon furrow application

    • According to the terrain and plant row spacing, choose the appropriate plant spacing or row spacing.
    • It is advisable to dig a trench with a width of 40cm and a depth of more than 40cm to the plant root distribution layer at the crown drip line (the ground where the crop roots grow to).
    • Apply Potassium Polyacrylate
      • Direct use. Sprinkle potassium polyacrylate particles directly into the dug ditch, fully mix with the fine soil in the ditch according to the ratio of 1:1000, cover the soil (do not step on it) into a concave shape (to collect water), and immediately water it thoroughly.
      • Pre-mixed water and use it. Apply the gel formed by mixing potassium polyacrylate and water into the dug ditch, mix it with the fine soil in the ditch according to the ratio of 1:5, and cover the soil (do not step on it) into a concave shape (to collect rainwater). Then pour water once.

    Strip furrow application

    • Dig a ditch 60cm long, 40cm wide, and 60cm deep along the drip line of the crown (where the roots of the crops grow) on one or both sides of the plant.
    • Apply Potassium Polyacrylate
      • Direct use. Sprinkle potassium polyacrylate particles directly into the dug ditch, fully mix with the fine soil in the ditch according to the ratio of 1:1000, cover the soil (do not step on it) into a concave shape (to collect water), and immediately water it thoroughly.
      • Pre-mixed water and use it. Apply the gel formed by mixing potassium polyacrylate and water into the dug ditch, mix it with the fine soil in the ditch according to the ratio of 1:5, and cover the soil (do not step on it) into a concave shape (to collect rainwater). Then pour water once.

    With fertilizer

    If the water retaining agent and fertilizer are applied together, there are two application methods:

    • Staggered ditch method. This method can avoid the influence of chemical fertilizers on the water-absorbing and water-retaining effect of the water-retaining agent, and at the same time take into account that the plants can not only absorb the nutrients of chemical fertilizers but also absorb the water released by the water-retaining agent.
      • Dig a ditch in the middle of the two plants and apply water retaining agent on one side, and fertilizer on the other side.
      • Ditch both sides of the plant and apply water retaining agent on one side and fertilizer on the other.
    • The water-retaining agent is on the top and the fertilizer is on the bottom. The water-retaining agent and fertilizer are applied in the same ditch, and when the water-retaining function is emphasized, the method of applying the water-retaining agent on the top and the fertilizer on the bottom can be adopted.
      • Note: The depth of the ditch is generally more than 40cm, because the water-retaining agent will be decomposed by microorganisms. The microorganisms are more active as they go to the ground, which accelerates the decomposition speed of the water-retaining agent. Water-based: The deeper the water-retaining agent is buried, the deeper the plant’s roots will grow, and the more solid and developed the tree’s root system, the better the effect.

    For annual crops

    The following are the usage methods of annual crops (grain, vegetable, cotton, fodder, melon, bean, tobacco, mushroom, peanut, etc.).

    Coated seed dressing

    Wet mix coating

    • Mix the seeds into the gel-like water-retaining agent (made by mixing 80-100 mesh water-retaining agent with water).
    • After fully stirring, spread it out indoors to dry in the shade or pile it up for 1 to 8 hours, so that there is no adhesion between the seeds and a layer of coating is formed on the surface (small seeds such as millet should be lightly rubbed to disperse after drying in the shade or add fine soil and mix well ) can be sown after.
    • The ratio of water retaining agent, seeds and water is 1: 500: 200.

    Dry mix coating

    • Soak the seeds in water for at least 3 hours.
    • Take it out and let it dry until the skin of the seeds is moist and there is no adhesion between the seeds and spread them evenly.
    • Water-retaining agent and seeds according to the ratio of 1:1000, sprinkle the water-retaining agent (80~100 mesh) evenly on the surface of the seeds.
    • After repeated vibration or rubbing to form a coating on the surface of the seeds, they are sown.

    Fluid seeding

    • A proper amount of water-retaining agent and water are made into a hydrogel at a ratio of 1:300.
    • Mix well with the seeds.
    • Sow into the soil with a special fluid seeder.

    Seedbed raising

    • Mix 1/5 of the total weight of the planting layer with a gel agent (dry product 5~8g/㎡, accounting for about 0.1% of the soil layer) on the seedling raising soil ridge (furrow) and in the planting layer soil and mix it with fine soil after sowing.
    • Cover the surface with pure soil without water-retaining agent.

    Base application for crop planting

    • Use 1~2kg potassium polyacrylate gel/square meter, and apply it evenly into the planting ditch
    • Mix evenly with hole soil
    • Cover with soil after planting.

    Planted crop topdressing

    • Dig a parallel trench at a distance of 5-20cm from the main stem of the plant (more than 410cm deep to the root distribution layer)
    • Sprinkle 1~2kg of potassium polyacrylate gel into the ditch evenly per square meter.
    • Mix well and cover with soil.

    Edible fungus

    1. Prepare the edible fungus culture material according to the routine. Then add about 50% of the dry cultivation material, add the water-retaining agent hydrogel and mix it evenly.
    2. The cultivation materials using water-retaining agent and water-absorbing gel are preferably piled and fermented first, and then bagged and sterilized for cultivation or directly cultivated. For sterilization treatment, normal pressure or high pressure can be used (sterilization time and cooling time can be slightly longer). The management methods of other cutting and cultivation links are the same as conventional ones.
    3. The water-retaining agent water-absorbing gel can also be used to retain water in the covering soil layer. It not only reduces the workload of water replenishment, but also because it does not affect the air permeability of the culture material, a balanced water supply can stimulate the growth of mushroom buds, increase the density of fruiting, and improve stamina.
    4. Utilizing the characteristics of the water-retaining agent to repeatedly absorb and release water, the cultivated fungus waste is then discharged to absorb water, and can be recycled and cultivated after fermentation.

    For gardening

    Root dip

    Put the flower seedlings into the gel (made by mixing the dry product of 80-100 mesh water-retaining agent with water) and dip the roots before planting.

    Potted planting

    • Mix 1 part of gel with 2~5 parts of soil (the amount depends on the water demand of the crop) and mix well.
    • After mixing with the soil, put a small part on the bottom of the flowerpot first.
    • After planting, fill it to 70% full.
    • Then cover the surface with more than 2cm of pure soil.

    Topdressing with grow bags and pots

    • Drill holes around the roots of the plants to the depth where the roots of the plants are concentrated.
    • Mix the water-retaining agent and fine soil in a ratio of 1:10 and fill them into the holes.
    • covered with a thin layer of soil.
    • Water thoroughly.

    Trees and shrubs

    • According to the area of the green belt, use 0.5~1kg/square meter gel, mix it with the root soil first, and then plant it.
    • Cover with soil after planting seedlings.
    • watering.

    Topdressing of trees and shrubs

    • For flower shrubs, dig a ditch with a width and depth of more than 20 cm to the root distribution layer at a distance of 10 to 30 cm from the trunk
    • According to the area of the green belt, use 0.5~1kg/m² of polypropylene high-potassium gel, mix it with about one-third of the excavated soil, and then apply it evenly, then cover the remaining soil and make it into a concave shape to collect rainwater.
    • For the arbor, dig 3 to 6 pits with a width of more than 20 cm and a depth of more than 20 cm to the root distribution layer within the crown drip line, apply 0.5 to 5 kg of gel agent on average per plant, and then cover with soil.

    Long-distance transplanting of trees

    Root dip

    After using this method, the survival rate of the tree can be guaranteed to be over 98% after long-distance transportation for dozens of hours.

    • Use a gel agent (80~100 mesh dry product of water retaining agent and stir it with water) and add appropriate amount of humus and rooting agent to make a thick slurry.
    • Dip the pulp all over the roots and wrap with a film.

    Base application

    • When planting, apply 5~100kg gel in the pit.
    • Arbors whose roots were dipped in potassium polyacrylate hydrogel were placed.
    • Overburden.
    • Watering.

    For Lawn

    For new lawn

    • Potassium polyacrylate is mixed with water to form a hydrogel.
    • According to the dosage of 1~1.6kg potassium polyacrylate/m², fully mix the hydrogel with the same amount of fine soil, and spread it evenly on the flat land.
    • The turf can be planted after a little clean soil cover.

    For existing lawn

    • First poke the lawn with multi-toothed nails to make some relatively uniform small holes.
    • Then spread evenly according to 5~8g/m² water retaining agent particles.
    • After spreading, use a slightly pressured spray water to flush the granules of the agent into the small holes.
    • Water well for the first day or two.

    With Slow release fertilizer

    We can use it with “slow-release fertilizer”, “bacterial fertilizer activator”Slow release fertilizer.

    • Slow release fertilizer
    • Several water-soluble fertilizers such as urea, auxin and root agents (strong acid and alkaline products cannot be mixed) can be dissolved in water
    • Add potassium polyacrylate particles to the solution to absorb it, and become a slow-release fertilizer for fertilizers.

    It prevents the loss of fertilizer and medicine, achieves the triple effect of balanced water supply, fertilization and drug administration, significantly improves the efficacy of fertilizer and medicine, and saves the amount of fertilizer and medicine.

    Bacterial Fertilizer Activator

    Green food requires biological fertilizers, and biological bacterial fertilizers require soil moisture to promote the activation and reproduction of bacteria.

    It is the best match to mix this agent with biological bacterial fertilizer, which can bring out the best in each other and can save fertilizer and increase efficiency.

    Frequently Asked Questions

    Is Potassium Polyacrylate Safe?

    Safety hazards to humans

    Potassium polyacrylate is non-toxic to the human body, and the pH value is neutral equal to 7.

    acrylic acid

    It is worth noting that the preparation of potassium polyacrylate is generated by the polymerization of potassium hydroxide and acrylic acid. So there is very little acrylic residue in the finished product.

    If acrylic acid is excessive, it can cause irritation to human skin, especially the eyes. Therefore, when the manufacturer sells potassium polyacrylate, it will provide the MSDS (material safety certificate) of potassium polyacrylate, which has proved that the residual amount of acrylic acid meets the requirements.


    In addition to the safety issues of acrylic acid, there are also some other unconventional safety issues due to the characteristics of potassium polyacrylate.

    • Potassium polyacrylate belongs to super absorbent polymers, a characteristic of water swelling, so it needs to be used carefully.
      • Potassium polyacrylate in small particles is in powder form, which can irritate the lungs and upper respiratory tract mucosa if inhaled.
      • After eating by mistake, it will absorb water and swell in the stomach and intestines of the human body, leading to indigestion.
      • Potassium polyacrylate after absorbing water is in the form of hydrogel and will slip if left on the ground.

    Environmental safety concerns

    As a water-absorbent polymer specially developed for agricultural water retention, potassium polyacrylate is not harmful to the environment. Although conventional potassium polyacrylate is not biodegradable, it can be degraded naturally in the natural environment. (It will be decomposed into water, ammonia and carbon dioxide under natural environment.)

    For some countries with extremely strict environmental requirements, manufacturers will improve the process of potassium polyacrylate, and graft starch to make it biodegradable.

    Note: Since the price of sodium polyacrylate on the market is much lower than that of potassium polyacrylate, unscrupulous manufacturers will sell sodium polyacrylate as potassium polyacrylate. Sodium polyacrylate will cause soil compaction and salinization in nature, so it is necessary to pay attention when purchasing.

    What are the disadvantages of potassium polyacrylate?

    Potassium polyacrylate is not suitable for all arid agricultural and forestry environments, and you need to pay attention to the following issues before purchasing:

    1. The water absorption and water retention capacity of potassium polyacrylate is greatly affected by the ambient temperature and soil composition. Excessively high temperature and salinized soil will affect the ability of potassium polyacrylate to absorb and release water. Therefore, when purchasing in large quantities, it is recommended to use samples for field testing first.
    2. Potassium polyacrylate needs to consider its cost as agricultural use. Potassium polyacrylate is generally considered to be very suitable for commercial crops and some common crops. When purchasing, it is necessary to pay attention to whether the estimated input costs and economic benefits are reasonable. Common financial benefits include:
      • Seeds: can promote seed germination and emergence, so that plants start early and healthy.
      • For crops: it can improve drought resistance and increase yield.
      • For fruit trees: it can increase yield and reduce fruit cracking rate.
      • Young trees or transplanted tree species: can improve the survival rate.
      • For landscape and golf grasses, costs can be controlled by reducing the frequency of irrigation.

    How to make potassium polyacrylate?

    Potassium polyacrylate is produced by the polymerization reaction of acrylic acid and potassium hydroxide.

    How much is Potassium Polyacrylate (2024)?

    The current price of potassium polyacrylate is about 2500-3000 US dollars.

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