AGRICULTURAL APPLICATIONS OF PUMICE
The frothy, sponge-like character of pumice makes it an ideal solution for controlling moisture and odor in pens, cages, stalls, loafing sheds, corrals, and trailers. Using pumice for this purpose also provides a multiplication effect: use-mixed with animal waste and bedding material, the muck is extracted and composted, where the pumice works to improve the composting process. Then, when the pumice-augmented compost is spread and tilled0 into ag soils, the pumice works as a long-lived, highly effective soil amendment. The process can be repeated many times, as the benefits are cumulative. Multiple applications over time are especially effective in poorly structured native soils.
[0] Immediate tillage is not strictly necessary, as the pumice-manure compost mixture will be worked down into the topsoil over time by hooves (pasture applications) or by regular planting and harvesting activities.
The first stage of the pumice-benefit cycle in livestock operations begins here: providing moisture and odor control in confined animal spaces. Stages two (improving the bedding and waste composting process) and three (improving compost-dosed crop fields and pasture soils) follow.
Proven Absorbent
Pumice is naturally absorbent by virtue of its foamed-stone nature. Lightweight and durable, Pumice has a long commercial history for use in absorbent products for oils and industrial fluids. Ag products using pumice also have been on the market for years. Pumice is used in soil amendments and engineered soils to provide moisture holding capacity. Pumice attracts and holds moisture in three ways: absorbing liquids into internal pores (without swelling or becoming soggy), holding moisture on the rough, amorphous terrain of the particle surface, and trapping moisture between pumice particles. The between-particles trap-and-hold function is especially effective in grade blends with a high fines content.
PUMICE OVER SOIL FLOORS. Loose pumice, when spread liberally over native soil floors in stalls, coops, and corrals, will control mud and facilitate drainage in heavy rains. It is especially effective in heavy clay soils. Also effective around heavy traffic areas that develop deep mud—like gates and doorways. Nor will pumice become soggy or slippery when wet. The grippy-surface nature of pumice also helps it bind together—with itself and the native soil. If spread before mud is present, it can be raked deep into the soil to form a no-mire matrix. Pumice will last a long time, even broken down over time beneath heavy traffic, those fines still function to stabilize wet soil, prevent mud, and facilitate drainage.
PUMICE WITH BEDDING MATERIALS. In coops and stalls, pumice can be layered with bedding materials like shavings, straw, hay, or shredded cardboard to provide additional moisture absorbing capacity—extending the functional lifespan of the bedding by as much as 30%. Having an absorptive material like pumice in the bedding also helps contain urine discharge to a smaller area.
COMPOSTABLE BENEFITS. When bedding is changed and composted, the pumice will add functional benefits to the composting process as well—mitigating VOCs and holding onto beneficial nutrients. Then, when the finished compost is ready for the garden, pumice again adds value, providing a non-consumptive element to the compost that works to condition the soil and improve the physical structure of the root zone.
X-REF IMPROVING THE WASTE COMPOSTING PROCESS (BELOW)
Control Odor
Excess moisture leads to odor. The combination of standing water/gooey mud, manure, and urea-rich urine make for an especially nasty stench. Pumice does a remarkable job of containing odor by controlling moisture and absorbing and trapping stinky compounds. How? Ammonia is the byproduct of bacteria breaking down the urea in urine and unabsorbed protein in manure. With pumice in place to absorb urine, less urea is available for bacteria to work on.
Once use-mixed with manure and bedding material, the muck can be composted, with the pumice working to improve the composting process and mitigate odor.
Safe Dust
Pumice is amorphous in structure—non-crystalline—and so, beyond being a nuisance dust, provides no respiratory hazard. See the material Safety Data Sheet (SDS) and other documents, linked below.
Introducing pumice into the composting process provides benefit on two levels. First, pumice provides a buffer to the extreme volatilization taking place in the decomposing matter, mitigates nitrogen loss, and provides inert bulk to facilitate airflow. The second benefit comes when the pumice-amended compost is introduced in the soil, as pumice provides long-term structural improvements to poor native soils well past the life-span of the compost itself.
Improving the Composting Process with Pumice
A handful of studies (referenced below) show the value of pumice to amend composting matter and improve the overall process, especially in trying to meet the challenges presented by various feedstocks.
Pumice delivers from start to finish: 1) Moisture and odor control in confined animal spaces; 2) Improvement to the composting process; 3) Steady in-soil structural, moisture-retentive, and drainage improvements long after the organic compost elements are consumed.
REDUCTION OF VOCs. Research published in Biosource Technology1 studied the use of natural amendments when composting poultry litter (blended at a 1:10 volumetric ratio) to reduce the levels of Volatile Organic Compounds (VOC). At 100 days, researchers found pumice significantly (at an 88% rate) reduced VOC production. Pumice out-performed all other materials tested.
[1] Removal of Volatile Organic Compounds by Natural Materials During Composting of Poultry Litter. (Bioresource Technology, 2008) Department of Environmental Engineering, Ondokuz Mayıs University, Samsun, Turkey; by N.G. Turan, A. Akdemir, O.N. Ergun
NITROGEN LOSS MITIGATION. In a follow-up study2 researchers looked at using natural amendments to improve nitrogen availability by mitigating NH3 volatilization in composted poultry litter. They found that yes, the addition of certain natural materials significantly reduced NH3 volatilization. In particular, only 26% of initial total N was lost from the compost amended with pumice.
[2] Nitrogen Availability in Composted Poultry Litter Using Natural Amendments. Department of Environmental Engineering, Ondokuz Mayis University, Samsun, Turkey; by N. Gamze Turan. 2009 Feb
BULKING AGENT. Bulking agents are introduced to composting matter to reduce cost, labor, and composting time. They can also increase compost quality and nutritive values. The bulking agent of choice is determined by what is being composted. Wet materials, for example, benefit from a low-moisture, highly absorbent amendment like pumice.
In another study published by Biosource Technology3, the contributions of pumice when used as an inert bulking agent in composting sewage sludge was studied and quantified. Pumice, with its foamy pore structure and absorbent nature, was found to significantly improve the biological reactions in the composting process—material porosity, water-holding capacity, nitrogen absorption (promoting ammonia assimilation to organic nitrogen rather than loss to volatilization), and accelerating the composting period.
As an inert mineral amendment agent, pumice significantly outperforms organic bulking agents like straw, husks, sawdust, or wood chips. Unlike organic agents, pumice does not breakdown and compact during the composting process, rather, it performs consistently, blends readily, is economically sourced, and easy to store. The physical character of pumice can also serve as a carrier for introducing additional elements to the bio-formulation, such as sucrose3 (to add a carbon source and provide a growth platform to quickly ignite microbial action).
[3] Usage of Pumice as Bulking Agent in Sewage Sludge Composting. (Bioresource Technology, 2015) Harbin Institute of Technology, Harbin 150090 & School of Environment, Henan Normal University, Xinxiang 453007, China; by Chuandong Wu, Weiguang Li, Ke Wang, Yunbei Li.
Non-Consumptive Soil Conditioning
Compost adds vital nutrients to poor or depleted soils while also providing a structural benefit, opening the root zone to facilitate drainage and gas exchange. But that physical improvement is short-lived: once the organic matter is exhausted, the compost-supported structure collapses, and so does the benefit. In gardens, flowerbeds, and other regularly tilled applications, the compost can be re-introduced as needed, but for landscaping infrastructure, perennial crop fields, or reclamation projects, poorly-structured soils need a long-lived amendment. Pumice-blended compost is ideal. The soil gets both a nutrient charge and enduring structural improvement.
High-value perennial crops can thrive in poorly structured native soils when amended for the long-term with pumice.
PUMICE-AMENDED SOIL WORKS. A study4 published in the Journal of Central European Agriculture (2005) measured strawberry seedling growth in pumice-amended soil and determined “important level” increase in growth, attributed to the studied enhanced moisture retention and pore size distribution factors contributed by the pumice. Another study5 concluded “that pumice may be effectively used in specific amounts for improving aeration and bulk density conditions of poorly structured soils.” The Australian Journal of Crop Science published a study6 that explored pumice use to achieve gains in soil moisture absorption and retention for corn crops. The results: “pumice significantly increased the amount of soil moisture retention compared to control. Growth characteristics of maize (vegetative growth and yield) were significantly improved with increasing amount of pumice concentration.”
[4] Effect of Pumice Amendment On Physical Soil Properties and Strawberry Plant Growth. Ustun SAHIN, Selda ORS, Sezai ERCISLI, Omer ANAPALI, Ahmet ESITKEN; Atatürk University, Department of Agricultural Structures and Irrigation, Erzurum-Turkey
[5] Addition of Pumice Affects Physical Properties of Soil Used for Container Grown Plants. Ustun SAHIN, Omer ANAPALI; Agriculturae Conspectus Scientificus (ACS) 01/2006; 71(2)
[6] Soil Water Retention and Maize (Zea mays L.) Growth as Effected by Different Amounts of Pumice. Ashraf Malekian, Einollah Valizadeh, Mona Dastoori, Sohaila Samadi, Vahid Bayat; Department of Agriculture, Payame Noor University, PO Box 19395-3697, Tehran, Iran
As mentioned above, pumice is widely used as an industrial absorbent for viscous oils, chemicals and other fluids. Livestock effluents can also be bulked up for composting or transport with pumice.
ABSORB AND HOLD. Pumice absorbs and holds moisture by means of a physical process that happens on three levels: liquid is held within the cavities and vesicles of each frothy pumice particle, on the complex, amorphous surface of the granules, and in between the grippy particles themselves. More fines mean a tighter particle matrix and more watery liquid holding capacity while larger granules catch and hold the heavy sludgy stuff. Pumice grade blends can be formulated to meet the variety of challenges posed by the waste stream. For example, thick, viscous effluent can be tackled with a pumice-grade blend containing enough large, frothy granules to bind up the heavy, sludgy bits with a dose of fines to take up the leftover watery stuff.
ANAEROBIC DIGESTION. Pumice serves as an excellent scaffolding for biomass colonies in the anaerobic digestion process, providing ideal growing conditions that reduce retention times and generate more methane gas.
X-REF PUMICE AS A LIQUID WASTE BULKING AGENT
Pumice works as an excellent filtration media for aquaponics systems. By some estimates, over half of all seafood consumed by humans is produced in aquaculture farms. The growth of aquaculture will continue as the demand for seafood products rise.
Hatchery operations, like this one, rely on aggressive and efficient filtration media to remove waste and turbidity from the water. The foamed stone nature of pumice makes it ideal for this use.
FILTRATION. Aquaculture operations are dependent on a reliable source of water. And because most water is shared with both upstream and downstream users, incoming and/or outgoing filtration is needed. And in systems that recycle/recirculate water, filtration is critical. Pumice is a proven water filtration media, used in large-scale municipal and industrial water and waste-water treatment facilities and in smaller, sand-filter-type tank systems. Pumice is a durable, aggressive filtration media with large pore volumes and surface areas, ideal for treating effluent waters. Pumice media works both as a mechanical filter to remove suspended solids and as a growth medium for biomass organisms in either aerated systems or anoxic systems.
Perhaps the use for which pumice is most well known is as an industrial abrasive and polish. Pumice is an amorphous foamed volcanic glass with a friable character—meaning no matter how fine pumice is crushed, it retains its functional, knife-edged structure. That useful structure is a surface covered with a profusion of sharp edges and riven with various-sized pores. Pumice dust is also hydrophilic, meaning it has a strong affinity for water. Pair the abrasive and hydrophilic natures and you have the ideal doom dust for unwanted insects.
Knife-edged and thirsty, fine pumice powders work as cutting, life-sucking mechanical insecticides.
HOW IT WORKS. A mechanical insecticide works primarily as a desiccant. The abrasive, cutting edges of pumice scratch and cut through the waxy and oily protective outer layer (epicuticle) of insects. Once contacted and adhered, the grippy, thirsty pumice powder continues to abrade and scratch that protective outer layer. Death results from a combination of passive desiccation, structural damage, and actively pulling body-fluid lipids out of the insect. Depending the the insect, fine pumice dust will also clog the breathing pores.
ADVANTAGES. Long-lived residual effectiveness when applied to cracks and crevices and out-of-the-way places where insects hide. A non-chemical solution, with no resistance or immunity built up by insects over generations. Dusting applicators (bulb-type, tube-type) are readily available. Can also be applied as a slurry. The variety of grade sizes allows for engineered dusts to expand utility, say a broad-spectrum combination of larger, mass-anchor particles with adhered ultrafine particles or a particle-size blend specific to an insect. Reduced effectiveness in humid climates.
MECHANICAL BARRIER. Pumice also functions as a mechanical barrier and repellent because some insects will not crawl on it or feed on foliage dusted with it.
New Construction: apply in crawl spaces, inside wall cavities, around utility penetrations, under cabinets and food storage areas. Inside Living Spaces: apply to crevices, under and behind appliances, cabinets, closets, penetrations through foundations (vents, utility pipes, window), pet sleeping areas and bedding, indoor animal enclosures beneath bedding litter. Grain Storage: treat grain immediately after harvest; use around silos. Growing Crops: applied as a dust or a slurry. Livestock Enclosures: in and around coops, stalls, sheds (especially in bedding), and feed storage.
SAFE TO USE. Pumice contains no crystalline silica, so presents no breathing hazard (beyond being a nuance dust) to people, pets or livestock.
Rodentia-class furry critters (like chinchillas and degus), and poultry (like chickens and game birds), use dust bathing as a means of keeping fur and feather clean of oily gunk and to combat parasites.
Adding pumice powder to the containers or dust-bathing excavations used by poultry will improve the effectiveness of the dust for cleaning and parasite control.
PUMICE DUST. A long time ago, somewhere high in the Andean mountains, a chinchilla herd found a drift of pumice powder and fell in love—they’d found dust-bath heaven. When you have up to sixty hairs growing out of one hair follicle and live in a dry climate, a water bath simply will not do.
Examine pumice dust under magnification and you’ll see what is best described as a foamed stone. The nooks, crannies, and gunk-grabbing edges of each pumice particle are ideal for capturing dirt and absorbing oils from fur, feathers and skin.
Poultry and game birds also naturally seek out dust-bathing opportunities—digging themselves down into some kind of loose dry material and then wiggling and rolling and scratching and throwing it around until they’ve worked the dust down through the feathers to the skin. In addition to a cleaning function, the birds also use dust-bathing as a means of controlling blood-sucking parasites—mites, lice, ticks, and fleas—that afflict them. Dust, especially when made up of sharp-edged particles like pumice, both clog parasite breathing pores (death by suffocation) and cut and scrap away the protective waxy coating on parasite exoskeletons (death by desiccation).
CHILLDUST™. Hess markets a premium pumice dust-bathing product to chinchilla keepers and breeders called ChillDust™. In cooperation with key breeders in the Empress Chinchilla cooperative, ChillDust is a blend of pumice grades developed for less airborne dust and maximum effectiveness. ChillDust™ particles have no crystalline structure, and thus do not present a respiratory danger to man or beast.
Chinchillas (and other dust-bathing critters) keep their skin and coat clean and healthy by energetically rolling around in pumice dust.
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