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PUMICE APPLICATIONS

Horticultural and Agricultural Pumice

When it comes to growing vibrant plants and turf, it’s all about the quality of the soil. The root systems of plants require a continual supply of oxygen, and the carbon dioxide respiration by the roots must be able to leave the root zone. This all-important exchange of gases is key to a good growing medium. That means the soil must resist compaction, yet be able to retain water and hold onto the nutrients necessary for plant growth. Adding pumice to garden soils, potting media, and crop fields can help meet those critical requirements. Pumice also has application in soilless processes.

Pumice as a Soil Conditioner

Pumice make an excellent soil conditioner, as it is highly porous, giving it excellent water and air holding properties. The advantages of using pumice in potting media and garden soils include:

Pumice IS THE PHYSIOCHEMICAL EQUILIVANT OF PERLITE

A 1992 study¹ done by the Department of Horticulture at the University of Illinois found the physiochemical properties of pumice—and hence, the performance value as a soil amendment—to be similar to those of perlite. Perlite enjoys a well-documented and successful place in potting soil formulations, but perlite is not as cost-effective as pumice for large-scale soil-conditioning projects such golf courses, urban parks and green belts, sports field complexes, ecology embankments, reclamation projects, and high-value crops.

Pumice for Soilless Growing Applications

Lightweight pumice is ideal for hydroponics, aquaponics, cutting propagation, and other high-efficiency soilless growing applications.

Pumice Improves Compost

A blend of compost and pumice makes sense on two levels. One, during the composting process, pumice provides a buffer to the extreme volatilization taking place in the decomposing compost matter. Two, pumice-blended composts provide long-term soil structure improvement and continues to contribute to the moisture and nutrient-holding capability of the soil.

Other Horticultural Uses for Pumice

Along with the applications detailed above, pumice is also used in the following horticultural processes and products.

Pumice in Rooftop Gardens. A significant amount of the soil needed for rooftop gardening and green-roof applications can be replaced with lightweight pumice. Not only does pumice-soil cut the overall weight load on the roof system, pumice, as detailed above, provides real value to soil function and structure as well.

Pumice as a Packing Medium for storing and transporting tubers, roots and bulbs. Pumice holds moisture without becoming soggy.

Landscaping Mulches with Pumice Stone. Coarse-grind pumice makes an excellent and attractive mulch for flower and shrubbery beds. The soil beneath the mulch stays moist longer and is less likely to compact from watering. Weed problems are minimized with a couple of inches of pumice mulch. Pumice does not break down, so does not need to be replaced. Our white pumice can also be color-dyed if necessary.

Agricultural Uses for Pumice

Amending poor native soils at the field-crop level demands an economy of scale that furnace-expanded soil amendments can’t deliver. Pumice comes by its frothy, foamed-stone form factor naturally, and so is economical for large-scale soil amendment use (mine grades). And as a non-consumptive agent, the restructuring provided by pumice endures indefinitely.

Perennial Crops. When growing perennials, restoring soil tilth with an annual plowing run is not an option. High value perennial crops can be successfully grown in poorly structured native soils if the soil composition is amended with pumice—upgrading the soil texture in the root zone, mitigating compaction, facilitating drainage, improving moisture and nutrient retention.

Pumice as a Seed Coating. Seed coatings are necessary when the natural state of the seed needs improved so as to be more compatible with precision seeding equipment and practices. The customized seed coatings possible with pumice produce seeds that are ideal in size, weight, shape and uniformity. Because of the highly absorptive and easy-to-bond nature of pumice, a pumice-blended seed coating can also serve as a kick-start nutrient carrier. Once sown into the soil, pumice also works as a long-term soil conditioner.

Pumice as a Chemical-to-Soil Delivery Medium. Pumice is chemically inert and readily absorbent, making it an ideal host for delivering useful agricultural chemicals such as herbicides, pesticides, fungicides, fertilizers. And once pumice has given up its chemical rider, it remains to condition and improve the soil.

Filtration Systems. Pumice has application in filtration processes as a media in tank filter systems, providing aggressive filtration either as a multimedia layer with the sand media or as a replacement filtration media. The grippy, sponge-like surface provides more aggressive filtration over sand, zeolites, or carbon-based medias, which work primarily by trapping impurities between particles. Pumice filters both between particles and via the surface texture of the particles themselves. The sharp, biting edges of pumice media are especially effective at catching and holding slippery organic particles when filtering for turbidity from surface irrigation water sources or water recycled from produce washing operations.

Managing Farm Waste. Liquid and sludgy ag wastes, with their high moisture content and poor air permeability, are difficult to compost. The solution: add a bulking agent into the feedstock to adjust the moisture content and porosity. Pumice is particularly effective in absorbing water and balancing moisture content. Pumice also acts to mitigate VOCs during the composting process. Manure and soiled livestock bedding can also be successfully composted with pumice working as an active amendment to the process, as detailed in the linked PDF document, below.

RECOMMENDED GRADES FOR HORTICULTURAL AND AGRICULTURAL APPLICATIONS
APPLICATION	HP GRADE
Soil Amendment / Conditioner	1/8 Fines MN | 3/8 x #8 MN | 3/8 x #8
Soilless Grow Media	3/4 x 5/16 | 5/16C | 3/8 x #8 | #10 | 8/12B | 1/8 Fines MN
Landscaping Mulch	3/4 x 5/16 | 5/16C
Compost Amendment	1/8 Fines MN
Seed Coating	FF LHM
Filtration Media	#3 | #4 | #5 | #7 | #10
NOTE: The grades selected above are typical and representative. Please contact us regarding your product, project, or process for help to determine the ideal grade or grade blend.

GET A PUMICE SAMPLE

If you’d like to sample a pumice grade (or several), we have a nice selection of stock pumice grades available to purchase in small quantities via our Pumice Products Store.

If you’d like to run tests and trials using our pumice in your commercial product formulation or industrial process, please contact us at salesteam@hesspumice.com with your request. We look forward to answering your questions, helping you select the best grade for your process, or helping you explore the fit of pumice for your needs. PLEASE include your name, your company or organization, pertinent project details, ship-to address, and preferred contact information in the sample request email.