When it comes to soil amendments, there are many that it can be challenging to follow along.
Peat, perlite, moss, coco coir, rice hulls, just to name a few.
You may not have heard of rice hulls.
Are rice hulls good for potting soil?
Rice hulls are great for potting soil. They hold water but improve drainage, they bulk, so soil doesn’t compact, they improve space for oxygen and air, they add silica for your plants, and, they are environmentally friendly.
What Are Rice Hulls?
Rice hulls are a grain’s outer covering.
Rice hulls are extremely high in fiber, making it impossible or difficult for human consumption, so rice hulls are removed prior to bagging and shipping.
For a long time, the left-over rice hulls were burned to eliminate waste on rice farms.
That was until their use as a charcoal “toothpaste” and an additive to building materials, pillows, and pet food.
As the material became more popular and accepted, and the use of rice hulls started multiplying.
Until someone found out it was decomposing slower than compost, they have added rice hulls to soil.
Why They Are Good for Potting Soil
Rice hulls are one of the best amendments you can add to your soil.
Water Retention
Rice hulls soak up water. The soil dries out, and the plants can use the water from the rice hulls.
So, you won’t have to water as often, and the plant won’t be too mad if forget to water.
Bulk
How much space there is between soil particles is a big factor in good soil.
If there is not enough spaces between the soil particles, the soil can compact over time.
When there is enough space between the soil particles this allows better drainage better airflow more space for roots to develop and space for microorganisms to thrive.
When you add rice hulls you add a larger substrate which reduces compaction of the soil.
Always remember: Rice hulls do decompose over time and left unaddressed soil can compact from that process alone.
Neutral pH
Rice hulls have an often underthought attribute, they have a neutral pH.
Each plant has a desired level of acidity in the soil, therefore whenever you introduce anything to the soil, you must assume a certain level of acidity for that resource, and you must adapt accordingly.
This takes time, and can be challenging to find the appropriate balance, and can be expensive since you will have to buy all kinds of different resources.
This plays no role with rice hulls. Rice hulls add nothing, and subtract nothing, from the acidity of the soil.
Inexpensive
In this situation, what’s good for the soil is also good for your pocketbook.
Because rice hulls are discarded in the rice farming process, and previously the only option was to burn them to get rid of them, rice hulls are sold for very low prices.
What Else Are They Good For?
Rice hulls aren’t just super for the soil, they’re super for the plants too!
All of the forenamed factors, directly affect the health of a plant.
Plants need enough water, space for oxygen and water to stay in the roil, space to expand their roots, and the proper soil acidity for the plant.
Then, there are other benefits to your plants.
Mulch
Rice hulls can make mulch in your garden or your potted plants.
Just apply a layer of half an inch to an inch thick over the top of the soil.
When you water your plant, the rice hulls will absorb some of the water and act as a source of water when your plant needs some more.
The layer on top of the soil also acts as a barrier so the water evaporates more slowly than it normally does.
Using rice hulls as mulch will also work as a thermal protection layer.
On the hottest, sunniest days, the rice hulls will keep the sun off the soil, protecting your roots from extreme heat exposure.
On cooler days, the rice hulls will keep the heat in the soil so it doesn’t freeze.
Fertilizer
Rice hulls can act as fertilizer in two ways.
The first way is when you add them to the soil, they will break down.
They have a lot of lignin in them which inhibits decomposition, but they do break down completely in 2-5 years.
Decomposing matter, or compost, is an excellent fertilizer for soil.
You can also buy carbonized rice hulls, or you can make them. Carbonized rice hulls are made when the rice hulls are partially burned, but not to ash.
The burning process makes rice hulls even more amazing, because they will contain:
- carbon
- nitrogen
- phosphate
- potassium
- calcium
- and magnesium
If you have bought fertilizer before, you may have seen an NPK analysis, which is a the ratio of nitrogen, phosphorous, and potassium in the fertilizer.
Do you also notice that all three components of fertilizer are present in carbonized rice hulls?
Silica
Silica is a “superfood” for plants.
Silica is a naturally occuring nutrient in the soil and is actually one of the most abundant nutrients in the earth.
Two of the most important things silica does for your plants are:
Silica improves the cells of the plant. It strengthens the cell walls and makes the cells more efficient.
Once the cells are more efficient, they produce more cells which you can see as plant growth.
The other reason that silica is great for your plants is that it facilitates the plants ability to absorb other nutrients.
The bigger and stronger the plant, the more nutrients it will need to sustain foliage, flowers or branches, and strong healthy plants have an easier time absorbing and processing the nutrients.
And the Environment?
Yep, rice hulls rock, they’re even better for the environment.
You’ve probably heard of perlite, sphagnum moss, or peat as soil additives. Honestly, all of those are bad for the environment.
Perlite goes through a destructive mining process to remove the non-renewable glass from solidified lava.
Sphagnum moss and peat moss completely destroy a bog that takes years to form to harvest two types of moss.
Then, there are rice hulls, which is found on every grain of rice.
Almost 496 million metric tons were harvested in 2020, and it’s a renewable resource.
That means the same area could potentially produce another 496 million metric tons this year.
Rice hulls used to be discarded, thrown away, and burned. That was the only way to dispose of the waste from rice farms.
Instead: Rice hulls were composted and incorportated back into the soil, decompose naturally while adding value for your soil and plants.
Final Thoughts
Rice hulls are amazing for potting soil, good for your plants, and great for the environment too.
They add a tremendous amount of water retention, improve drainage and aeration, add silica to support your plants, are inexpensive, and can even be used as a mulch, and they are a sustainable substrate.
So why aren’t you using rice hulls?