Potassium polyacrylate - Superabsorbent polymer for Plants



Since the UCC company of the United States first applied SAP (superabsorbent polymer) to soil water retention in 1973, SAP has been gradually applied to the cultivation and transportation of seedlings in agriculture, forestry, and horticulture, breeding, improving soil fertility, and water retention, and inhibiting soil erosion.

There are two types of superabsorbent polymer, so choosing a reliable Agricultural Potassium Polyacrylate Manufacturer is very very important, to avoid that you order the wrong Agricultural Potassium Polyacrylate.

Basic info

NamePotassium polyacrylate
Chemical formula[−CH2−CH(CO2K)−]n
CAS Number25608-12-2
PriceUSD 3000/ton
Appearancewhite granule / transparent gel (before/after absorbing water)
Physical propertyNon-toxic, harmless, non-polluting, natural degradation
FunctionAbsorbing, retaining, or blocking liquid
Main applicationsabsorbing, blocking liquid with expanding
Common test itemsabsorption, absorbent rate, liquid permeability, residual monomer (as AA), particle size distribution.

Advantages for Plants

As a water-retaining agent, potassium polyacrylate has a strong water-retaining ability.

  • To absorb water hundred times its weight and become gel form;
  • Water gel can release water to plants when it's drought.

As we know, water is so important for plants. Potassium polyacrylate is just a "mini-reservoir" to keep releasing water to plants so that:

  • Increase yield of crop & fruiter;
  • Improve seed germination & emergence, give plants an early, healthy start;
  • Reduce irrigation frequency;
  • Release the fertilizer efficiency slowly;
  • loosen the soil and adjust salinization & PH.

How does it work?

Potassium polyacrylate works similarly to a sponge under the soil surface.

It is composed of a set of polymeric chains, which are linked together chemically to become a water-insoluble, net-like matrix that gently attracts and holds hydrogen molecules.

The immense size and weight of its molecular structure allow each potassium polyacrylate granule to absorb over 500 times its original weight in purified water.

Auto to release water for plants

It does not 'bind’ water tightly. The potassium polyacrylate granules release just the right amount of water in response to a plant’s root suction. There are no waterlogging or other ill effects caused by ‘free’ water filling air cavities in the soil.

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

Improving soil

Potassium polyacrylate maximizes plant growth by reducing plant stress. It also absorbs and releases soil nutrients, water-soluble fertilizer, and chemicals in the same manner as water, creating a healthy microenvironment in the plant root zone. The result is faster germination, quicker emergence of seeds, consistent growth, and higher, better-quality yields of edibles with less water and fewer inputs.

Applications Details

Soil conditioner

Potassium polyacrylate will absorb water and turn to water gel after rain or irrigate. And gel can release water to plants when the soil is dry enough. After releasing, potassium polyacrylate gel will turn to powder/granule and wait for the next rain.


As a soil conditioner, SAP mainly uses a good water absorption capacity of SAP, so that the water in the soil is absorbed by the resin, so as to reduce the loss of water in the soil and play a role in reducing heat conduction, which can reduce the temperature difference between day and night, which is conducive to the growth of crops.

At the same time, SAP can enhance the cohesion between the easily dispersible soil particles, so that the particles can bond with each other and agglomerate into water-stable aggregates, thus causing changes in particle size composition. The increase in the number of soil aggregates has a good effect on improving soil permeability, preventing topsoil crusting, and reducing soil surface water evaporation.

For clay soils with low water content in the soil, SAP helps to increase the air content in the soil, improve the physiological environment such as water, fertilizer, air, and heat around the root system, promote root system development, and expand the absorption area.

Period of validity

The period of validity is about 3-10 years and potassium polyacrylate can be slowly decomposed into potassium ions, ammonia, water, and carbon dioxide in the soil.

Seed coating

The use of SAP in plant seed cultivation by the mixing method and coating method can:

  • increase the germination rate,
  • shorten germination time,
  • Promote plant growth.

For example, dressing SAP with grass seed can improve the survival rate of aircraft seeding in arid regions.

The super absorbent is mixed with water at a concentration of 1% to form a gel, which is coated on the surface of the seeds or mixed with fertilizers, nutrients, insecticides, bactericides, humus, and other ingredients to make seed coating agents. Bud, revitalization, yield and other effects,

It can be used for the artificial sowing of wheat, corn, soybean, peanut, and direct seeding afforestation and grass.

The name of the cropEarly emergence/dayImprove seedling emergence rate/%rate of growth/%

Fertilizer coating

The fertilizer is coated with SAP and then fertilized so that the fertilizer can be released slowly without being washed by rainwater.

It can:

  • Improve the utilization rate of chemical fertilizers,
  • reduce waste caused by fertilizer loss and environmental pollution,
  • better display the excellent performance of varieties,
  • and also have anti-counterfeiting functions.

Seedling transplant preservative

In gardening and agriculture, it is often necessary to transplant various seedlings. If the seedlings are not kept well, the seedlings will die due to the drought of the roots during the transplanting period.

Therefore, the roots and soil are often dug together for soil protection of seedlings, which consumes a lot of manpower and transportation costs, and brings a lot of trouble.

SAP solves this problem and opens up a new way of transplanting seedlings.

In the transplanting of seedlings, it is only necessary to coat the SAP water-absorbing gel on the roots of the unearthed seedlings for water retention treatment, and no watering is required within a few days to half a month after transplantation, which can greatly improve the survival rate of the seedlings and the survival time of transplantation.


Important points to flowers

Water is the most important thing to plants. Give the flowers some water regularly, or they will wilt.

Flower won't grow well in poor soil.

  • Most flowers thrive in soils that are neutral, with a pH value of 7, or slightly acidic;
  • Sandy soil is lacking water/nutrient retaining ability.
  • Silt/clay soil is lacking air which is bad for roots.


  • Just like a "mini-reservoirs", it can continuously supply water to flower;
  • It can regulate PH value;
  • It can increase the water retaining ability to reduce the water/nutrient erosion;
  • It can release the fertilizer efficiency slowly;
  • Loose soil. Potassium polyacrylate will swell/shrink when absorbing/releasing water.

Compare with Sodium polyacrylate

Sodium polyacrylate’s price is about USD1200 / ton. (The price of inferior type can be lower than USD1000 / ton.)

As another type of super absorbent polymer, sodium polyacrylate is mainly used in producing absorption products such as paper diapers, and sanitary towels.

Unlike potassium polyacrylate, sodium polyacrylate‘s water gel won’t release water to plants and break down in a few days after mixing with soil.

This is meaning, sodium polyacrylate can’t help plants grow at all. Conversely, the sodium ion will let soil harden.

So sodium polyacrylate should not be used in agriculture.

But sodium polyacrylate‘s price is much lower than potassium polyacrylate and it’s hard to distinguish between them, there are some fake “potassium polyacrylate” is sodium polyacrylate in the marketing.

chemical namesodium polyacrylatepotassium polyacrylate
usagesthe absorbent material of diapers, sanitary napkins, etc.water-retaining agent for plants
appearance of absorbingwhite powder => white water gel => transparent water gelwhite powder => transparent water gel
the water-retaining ability of water gelstrong than the roots of plantsweaker than roots of plants, strong than soil
decomposition timein one weekmore than two weeks
decomposition productNa+, carbon dioxide, water, etc.K+, carbon dioxide, water, etc.

Does sodium polyacrylate help plants?

Sodium polyacrylate is widely used in every aspect of our life. And we can easily get sodium polyacrylate from paper diapers, sanitary napkins, etc.

Can we use sodium polyacrylate as a water-retaining agent for plants instead of potassium polyacrylate?

The answer is obviously no.

  • No water releasing function. Different from potassium polyacrylate, sodium polyacrylate (water gel) won’t release water to plants.
  • Bad for soil. Sodium polyacrylate will be decomposed into sodium salt which causes soil salinization.

How to devise them? (especially used in agriculture)

As sodium polyacrylate is much cheaper than potassium polyacrylate, some profiteers sell sodium polyacrylate as a water-retaining agent.

So we need to devise them before purchasing.

The simplest method is the sunlight test:

Expose the water gel to the sun, sodium polyacrylate (or low-quality potassium polyacrylate) water gel will melt in 7 days.


Lab test

Water holding capacity test

soil: 500 ml; water: 750 ml; SAP: 5 grams

The wilting point test

It can increase the water holding capacity of soils and delay the wilting point.

A sandy soil treated with 2 grams of potassium polyacrylate per kg of soil holds water twice as long as untreated soil.

Local Field Test


Advantages for potatoes

  • Potassium polyacrylate improves soil's ability to hold water In the root zone and then release it to plants As they need it.
  • Potassium polyacrylate has also been shown to increase nutrient levels In leaf petiole samples.
  • Should be applied at 7 lbs per acre, in-furrow, with potato seed pieces, or at spring mark out before planting.
  • Potassium polyacrylate has no toxic components In the soil like plant residues.

Othello, WA-Russet Burbank Potatoes

Location: Othello, WA

Crop: Potatoes

Rate of potassium polyacrylate: 7 lbs per acre

Application: Applied In furrow at planting

Harvest: Replicated trial samples harvested By hand

Yield Results

** Field**UntreatedTreatedIncrease
Total LbsHendricks Road159 lbs173 lbs14 lbs
Tons/AcreHendricks Road38.68 Tons43.371 Tons3.51 Tons

Hermiston, OR - Premier Potatoes

Location: Hermiston, OR

Crop: Potatoes

Rate of potassium polyacrylate: 7 lbs per acre

Application: Applied In furrow at planting

Yield Results

** Total Yield**Total UsableMin 4 ozMin 6 ozMin 10 ozMin 14 oz
Untreated37.55 Tons91.9%17.4%30.9%24.7%18.2%
Treated40.9 Tons94.9%10.2%30.8%26.9%27.0%
Difference+3.46 Tons+3.8%-7.2%-0.1%+2.2%+5.8%

Mt Vernon, WA - Chieftan Red Potatoes

Grower: Sterling Potato

Location: Mt Vernon, WA

Crop: Potatoes

Variety: Chieftan Reds

Rate of potassium polyacrylate: 7 lbs per acre

Application: Applied In furrow at planting

Yield Results

** Treated**UntreatedIncrease
Total Culls0.0%1.8%-1.8%
1-7/8" to 2.25"13.6%22.4%-8.8%
2.25" to 2.5"22.7%29.0%-6.3%
2.5" to 2.75"9.1%13.3%-4.2%
2.75" to 3.0"36.6%23.8%+12.8%
3.0" to 3.25"3.5%3.3%+0.2%
3.25" to 3.5"8.9%2.9%+6.0%


Lettuces in Japan

Result: The lettuces in the Pack Rain pot have increased by 64.13% in yield.

Citation: Potassium polyacrylate field test: lettuce


Oats in Argentine

Result: “These last pictures are from last week, and are to reap almost. After we move the machine to harvest, the yields of oats with your SAP increased almost 60%, which is far excited than we expect.”

Citation: Potassium polyacrylate field test: oat

Dry beans

Dry beans in America

Result: +13. 9% yield/acre.

Citation: Potassium polyacrylate field test: dry beans


Onions in America

Result: +5.13% yield/acre.

Citation: Potassium polyacrylate field test: onion


Potatoes in America


Citation: Potassium polyacrylate field test: potato

How to Choose Potassium polyacrylate

High-quality potassium polyacrylate has the following characteristics:

High salt tolerance

The salt in the aqueous solution can affect the water absorption rate of potassium salt, and the leachate in the soil contains salt. Therefore, the salt resistance of potassium polyacrylate is very important.

The salt resistance of SAP is mainly determined by crosslinking density, structural composition, solution properties, surface morphology, and preparation methods.

According to the influence of salt solution on the water absorption of SAP, the following methods are used to improve its anti-electrolyte performance:

  • Introduce diverse groups
  • Choice of crosslinking agent
  • Improving the density of ionic charges and the degree of ionization of ions in the interpenetrating network of water-absorbent resins
  • Complex with other ingredients

High SAP gel strength

The water absorption rate of SAP water-absorbing gel will be affected by the pressure of the soil in the soil, so the strength of the hydrogel is very important.

Generally speaking, gel strength and water absorption rate contradict each other. The strength of hydrogel increases with the increase of cross-linking degree, but the higher the cross-linking degree, the lower the water absorption rate and the less water absorption. Therefore, it must be based on the requirements. The water absorption amount and water absorption rate are controlled to a certain degree of cross-linking to achieve the corresponding strength.

Another method is to add inorganic minerals. The strength of inorganic minerals is much higher than that of SAP. Combining SAP with inorganic minerals is beneficial to improve the gel strength of SAP. Not only does the water absorption performance remain unchanged, but also the durability is good. High water retention performance.

Slow/controlled-release fertilizer performance

SAP can be combined with fertilizers to form a water-retention slow/controlled-release fertilizer that integrates materials and functions so that it has the dual functions of slow-release fertilizer nutrients and water retention.

The swelling degree of SAP in the soil is low and the fertilizer release is slow, thus showing good slow-release performance.

SAP and fertilizer are combined in 3 ways: physical mixing (adsorption or granulation), coating, or chemical synthesis.

Common SAPs on the market

There might be 3 types of Ag-SAP you'd meet:

1. Fake type - Never purchase

For more money, some profiteers would sell defective SAP or industrial purpose SAP as fake type "Ag-SAP".

This type of SAP's main composition is sodium polyacrylate.

And it:

  • won't repeatedly absorb & release water in soil;
  • would break down into sodium which causes soil salinization.

2. Common type

As we know, common Ag-SAP's main composition is potassium polyacrylate.

There are two types of common Ag-SAPs:

a. Potassium polyacrylate with acrylic amide.

  • advantage: a long period of validity (available in the soil for 3-6 months);
  • disadvantage: acrylic amide's a kind of cancerogenic substance.

b. Potassium polyacrylate without acrylic amide.

  • advantage: no acrylic amide and totally harmless;
  • disadvantage: a short period of validity (available in the soil for 1-3 months).

3. Improved type

There are some types of Ag-SAPs improved on some side like:

  • Starch-based SAP – which is totally biodegradable in soil and brings nutrient to plants;
  • Minerals-based SAP – which is available in the soil for years.

How to use?

Seed coating

  1. Make Ag-SAP water gel;
  2. Mix water gel with seeds (2:5);
  3. Wait for 1-8 hours before sowing the seeds.

Grow seedlings

  1. Make Ag-SAP water gel;
  2. Mix water gel with soil (1:5);
  3. Grow seedlings with the mixed soil.

Planting crops

  1. Make Ag-SAP water gel;
  2. 50-150 kg water gel per acre dosage, along with seeds hole application or ditch application to the soil around the seed.
  3. Cover seeds with soil.

Topdressing for crops

  1. Dig a 10-20cm deep ditch beside the crops
  2. Make Ag-SAP water gel;
  3. Fill ditch with water gel (50-150 kg water gel per acre);
  4. Cover ditch with soil.

Planting/transplanting trees

  1. Make Ag-SAP water gel in a big plastic drum (or another nonmetallic container).
  2. Dipping roots in the drum before planting.
  3. Mix water gel with soil (2:5);
  4. Planting trees in the hole after laying the soil mixed with water gel.


  • Avoid metal containers;
  • Protect from light and moisture.

FAQs about sodium polyacrylate


Can I mix fertilizer with it?

Yes. By combining potassium polyacrylate and nutrients, your plants have the best advantage – both food and water.

Can potassium polyacrylate be reused?

Yes. Potassium polyacrylate becomes gel form after absorbing water. After gel releases the water to the roots of the plant, it will return to the granular state. There potassium polyacrylate granular can absorb rainwater or irrigation water again. The life of potassium polyacrylate in the soil is related to the degree of soil salinity and local temperature. It can usually reach several years.


Can increased moisture near root structure cause root rot?

Potassium polyacrylate granules will expand to many times their original volume, then contract and repeatedly expand based on the water available. This action forces soil particles apart, increasing aeration-the key element required to prevent root rot. Once the granules reach their maximum absorption, excess water is allowed to move deeper into the soil profile. This combination of idea water availability and good aeration promotes faster plant growth and minimizes the potential for root rot.

Does it affect a plant's water requirements for optimal growth?

Plants require a specific amount of water for optimal growth. Potassium polyacrylate doesn’t change that amount, but It does manage water more efficiently. Instead of water being dispersed into the soil or evaporating, it is absorbed by potassium polyacrylate and held for the plant to use as needed. This “bound water” more effectively and efficiently nourishes the plant.

Does it change the nature of the moisture it absorbs?

No, it triggers no chemical reactions.

Potassium polyacrylate merely absorbs moisture and any water-soluble nutrients it contains, and remains suspended in the plant root zone, storing the moisture and nutrients in plant-available form.


How do seed furrow treatments enhance crop maturity uniformity in the field?

By applying potassium polyacrylate in seed furrows at planting, the germinating seed and seedlings have a constant supply of moisture and nutrients available for a more complete, consistent germination and seedling emergence.

Potassium polyacrylate removes variances caused by dry spots in the field for more uniform stand and crop development.

How long would it work in soil?

Factor One - Soil

  • Saltiness. Saltiness is a very factor for the life & performance of potassium polyacrylate;
  • Soil type. It's better to use potassium polyacrylate in sand soil than clay/silt loam.

Factor Two - Temperature

  • Extreme weather will reduce the lifetime of potassium polyacrylate. Deep culture is a good way to protect it.

Factory Three - Product quality

  • Fake type (sodium polyacrylate): less than one week

*Because sodium polyacrylate is much cheaper than potassium polyacrylate, sodium polyacrylate is sold by profiteer as potassium polyacrylate.

  • Inferior type: 2-4 weeks in soil
  • Common type: 1-3 months

*As common potassium polyacrylate's lifetime is a couple of months, it's important to seize the important period of plants (such as nursery stage, anthesis, fruiting period, etc.)

  • Improved type (like Pack Rain): 5-8 years

How often do I apply it?

In general, we recommend a fresh application of potassium polyacrylate with each new planting.

This ensures that it is in close proximity to the seeds (to increase germination) and roots.

How to use potassium polyacrylate for plants?

You can make the potassium polyacrylate gel first then mix it with soil.


Is it safe for the environment (biodegradable)?

Yes. Unlike sodium polyacrylate, potassium polyacrylate can be decomposed into water, carbon dioxide, and potassium which can improve soil and increase fertilizer efficiency.

Is it suitable for only one type of soil?

No, it provides benefits to all soil types. Soil particles in sandy soils are relatively large and have poor water-holding capability.

Potassium polyacrylate holds water, preventing it from moving past plant roots where it is needed most. Clay soils, which are more compacted, benefit from the increased aeration created as Potassium polyacrylate expands and contracts, which increases oxygen levels and water percolation.


What is potassium polyacrylate used for?

Potassium polyacrylate is a kind of super absorbent polymer used for agriculture. It can improve soil Mixing it in the soil can greatly increase the water holding capacity of the soil.

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