Frequently Asked Questions about Rice Hull mulch and Topdressing

What is rice hull mulch?

Rice hull mulch is the application of rice hulls to the top of a growing media or soil.  The purpose is to prevent the germination and growth of weeds. By providing a depth of around 1.25”, weed seed that lands on the container or ground are unable to retain the moisture and proper environmental conditions to grow.  This prevents the growth of weeds.

What is rice hull material?

Rice hull or husk material is the case or chaff of the rice.  It is a byproduct of the rice you purchase at the grocery store.  The hull is then compressed into a bag and sold to growers for use in their operation.

How is rice hull material sold?

Rice hull material is typically sold in 50lb bags or 30 cubic foot sacks. The 50lb bags are then put 16 on a pallet. This size is manageable for a machine operator to load in the field. The 30 cubic foot sacks weigh near 700 lbs and require a machine to move. They should be left for applications that utilize a large hopper where the sacs can be easily and safely unloaded.

Where can I purchase rice hull material?

Here are two suppliers that you can purchase PBH rice hull material from:
A.M. Leonard
Griffin Greenhouse Supplies

What is rice hull used for?

  • There are two primary uses for rice hulls. The rice hull can be used as an amendment to soil replacing and/or in conjunction with perlite to provide drainage in the growing media.
  • The second use is as a top dress or mulch product to prevent the germination and growth of weeds. By providing a depth of around 1.25”, weed seed that lands on the pot are unable to retain the moisture and proper environmental conditions to grow.

What alternatives are there to rice hull material mulch?

The issue of weed prevention is a persistent and ongoing issue in agriculture.  There are many options available for the grower.  Some common solutions are:  Bark mulch, pre-emergent herbicide, hand weeding, coir disks, herbicides.  There are both advantages and disadvantages to all of these solutions.

What is a rice hull blower?

A rice hull blower is a specialized machine that feeds rice husk from a hopper through a flexible hose and allow for dispensing to a precise location such as a container.  The machine is on wheels and is meant to be towed behind a nursery wagon.  Material is loaded into the hopper via an operator.  The material then feeds through a device called a rotary airlock.  This rotary airlock is a device that has large steel vanes welded to a shaft.  The outside of the veins run closely to the case to provide an airtight seal.  As the shaft rotates, material falls into the gaps between the veins and is carried to the bottom of the airlock where it falls into a pressurized air stream.  This air stream delivers the material through the hose and out to the desired location.  At the end of the hose is a device called a diffuser which is simply a larger area pipe.  This larger pipe reduces the airspeed and allows the rice hulls to fall out of the end of the pipe instead of acting as a jet and blowing material out of the container.

What is a rice hull blower used for?

The rice hull blower is for growers that have a need to dispense rice hull material in the field.  Dispensing in the field allows time for the container media or soil to settle.  It also allows for the operator to re-apply hull when necessary and does not require the rice hull to be applied in conjunction with inline potting.

Who needs a rice hull blower?

Growers that are looking for an alternative to currently available weed prevention methods.
Growers that is looking to reduce their chemical usage and dependency.
Growers that are planting in the field and are unable to run a machine in line with a potting machine.
Growers that are applying rice husk by hand.
Growers that have non-circular pots, utilize trays, or have special containers or processes that prevent rotating containers on a conveyor line.

What are the alternatives to a rice hull blower?

There are other options for applying rice hulls to containers in wholesale shrub nurseries.  Different rice hull topper systems and equipment are available that applies rice hull as part of the potting conveyor line.  This device rotates the pot as it goes through the machine.  Material is loaded into the hopper directly under the potting line or behind the convey line and requires 110v or 220v power source.  There are also some growers that apply rice hull by hand.

What is pneumatic conveying?

Pneumatic conveying is split into two types – Dilute and Dense Phase conveying.  These phases refer to the ratio of material to move and the amount of air.  Dilute phase has a high volume of air whereas dense phase utilizes high pressures and lower airflow.  The rice hull blower solution operates in the dilute phase moving material quickly through the hose.  Pneumatic conveying relies on a pressure difference between the beginning and end of the hose.  This pressure differential “pushes” the material through the hose.

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What does the warranty look like?

3 Year, Unlimited Hours Warranty – INCLUDED

What does it include?

Includes: Problem identification, remote trouble shooting of issue, support and instruction for proper repair, and providing replacement of failed parts.

What is excluded?

Excludes – Misuse of equipment (including using non horticultural potting mixes with high sand and field soil content) or improper care, such as leaving fertilizer in machine for an extended period of time.  Wear parts (chain, slats, wear plates or surfaces).  External physical damage inflicted on the machine.  Labor repair costs.

We will walk you through the repair process and make sure you're happy.

What about Service Parts?

Yes, we keep inventory of most all parts. Most all of the components are either US Sourced or a common off the shelf component. We are having some supply chain issues on components, but we are working through the best way to manage that.

What about Repair?

All of our machines are designed right here in the US.  We design these machines to be easily repairable by an inexperienced worker.  Should a problem arise, you won’t need to weld or fabricate a new part.  The entire machine is bolted together and you can simply bolt in a replacement part.

The hopper capacity seems low

We have heard that concern, I get it, you won’t be able to load a machine up and let a person pot plants for a day.

Some perspective – The rear load machine holds about 3/4 – 1 cubic yard which is up to about 200 gallons of material. That gives you about 15 minutes of runtime without stopping.

The reason for the smaller equipment size is to primarily keep the price and complexity down.

Increasing the machine size has a few unwelcome side effects:

-Increase horsepower requirements which means increased power – now you have to have dedicated power for the machine.

-Increasing the hopper size also increases the physical size of the machine which increases the overall cost and reduces portability

You may have not made a purchase on a potting machine in the past because of the overall cost.

We're being cautious around those concerns and trying to work within your business goals.

Is this production rate slow?

From time to time, we hear that our production rates appear slow. Look at it this way though. You have 5 or 10 workers running a high-speed line. SOMETHING GOES WRONG, you now have all these people standing around and/or you need to find a different job for them.

What's your real per man hour potting rate?

If you have a machine problem with a high-speed line you’re completely shut down.  With a cell-based design, you have a small part of the potting operation down.  Your efficiency is similar whether you have 1 or 4 people operating STILT.PRO machines.

Your business is complex, don't make it worse.

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