Why You Should Put Clay in Compost Piles


Steve Solomon recommends you add clay to compost piles, especially if you have sandy soils.

Putting Clay in Compost

Since I pretty much do everything Steve Solomon tells me to do, I started putting clay in compost piles some time back… but now I’m really getting serious. You can see me adding clay to the compost layers in the video I posted yesterday:

An article at The Food Garden Group in Tasmania reports good results with clay in compost piles:

The heaps made with clay, so long as they contain a reasonable amount of coarse material to enable some air movement, do not need to be turned.  The ingredients all get to soak and mix in a thick clay soup before stacking (putting a pile of food and drinks in every pantry) and the heaps seem to stay moist for a very long time. I recently opened up a heap I hadn’t touched for three months and it was still moist and generating warmth. A reasonable compost can be made by simply wetting the materials with clay slurry as the heap is built but remember that only the material which decomposes in association with clay particles is going to become durable humus/clay complex. A heap built this way will probably need to be turned and re-watered too. Think of the difference between a dish that’s been marinated compared to one that’s only been sprinkled with a dressing.

Clay is made up of very fine particles so the combined surface area of all the particles in a peanut sized clod might be equal to a tennis court or three Clive Palmer skins or some such mind boggling factoid. No wonder, then, that it can hold so much water. Also these particles carry a negative charge so each one is capable of forming bonds with positively charged particles (ions) like many of the essential plant nutrients. They gradually fill up with waste, sticking fast and firm to walls, floors and ceilings as the food in the pantries is consumed.

The resultant compost is packed with nutrients which are more or less available depending on how complex the chemical bonding with the clay is. What we have here is humus in close association with clay, a long lasting, water retentive material in which plant roots and soil organisms can find all the nutrition they are looking for. A material which will keep carbon, not only locked up, but also doing a great job for years to come.”

Putting Clay in Compost is Good For Sandy Soils

In sandy soils organic matter burns up a lot quicker than it does in clay soils. Clay is capable of hanging on to the good stuff for longer, binding with organic material and increasing its persistence.

If you make compost in an area where clay is not part of the soil, it’s easy to put clay in compost via buying bentonite. Just sprinkle it in as you layer materials – you don’t need as much clay as I dumped in my pile.

According to Infogalactic:

“The application of clay technology by farmers in northeast Thailand, using bentonite clay, has dramatically reversed soil degradation and resulted in greater economic returns, with higher yields and higher output prices. Studies carried out by The International Water Management Institute and partners in 2002–2003 focused on the application of locally sourced bentonite clays to degraded soils in the region. These applications were carried out in structured field trials. Applying bentonite clays effectively improved yields of forage sorghum grown under rain-fed conditions.[14][15]

Bentonite application also influenced the prices that farmers received for their crops. Production costs are higher, but due to more production and the quality of the food, clay farmers could afford to invest and grow more and better food, compared to nonclay-using farmers.”

Lots to think about. Make that compost stick around!


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Less than Impressive Cassava Harvests


I picked the most likely candidate in the overgrown cassava bed down the hill and dug it:

That’s barely worth feeding to the chickens!

Back when I grew cassava in North Florida, the roots would grow huge in the loamy sand. Here, I don’t know. People do get decent harvests, but my guess is the shade and the clay hurt our yields.

I’m going to try again and see if I can do better. These were grown in loosened soil but I think they could have used more sun.

We’ll see.

Tools for Digging in Georgia Clay


Digging in Georgia clay has reminded my of one thing that’s really been nice about being back in Florida: sand!

I know… people complain about the sand here. However, it’s truly a boon for the impatient gardener. You can dig a LOT in a short period of time, making getting to China that much easier than it is in clay soils.

Even awesome tools can fail. Ow.

When I used to live in Tennessee, I had hard and rocky clay. I had almost forgotten the pain. Sure, clay has its own advantages. It holds moisture and minerals, plus allows you to line ponds and dye all your clothing rust-red. But still… it’s hard to dig.

This last week when I was in Georgia, I decided to put in a small garden with my young niece and nephew. I had brought beans to plant, I had my Clarington Forge spade and fork, and there was a good sunny spot… so all was well.

Or so I thought.

Once I started trying to dig, I realized we were in trouble. Even with forged heads and sharpened blades, the tools literally bounced off the ground.

I don’t mean figuratively: I DO mean literally.

The tools… bounced… off… the… ground.

The soil there was harder than it was in Tennessee. My guess is because it was a concrete-like mixture of clay and sand together. Another problem: beneath the top inch or two of wet ground after a rain, the ground beneath was hard and dry. Not good.

Since I didn’t have any dynamite, I decided it was time to take a trip to Lowes World to see if I could find something to chop at the ground.

As a side note: before leaving Florida, I tried to pack my amazing Easy Digging grub hoe but it wouldn’t fit in the back of the car. I think it would have done wonderfully (and its long handle was more ergonomic than what I ended up buying) but there was no way to pack it without letting it hang out of the side of the car.

The police hate things like that, so instead I bought one of these:


After sharpening the blade and putting in about two hours of hard labor with that pickaxe, I finished digging a 14″ or so deep bed for planting beans. The entire bed was about a 3′ x 7′ and it definitely gave me a workout, plus some good blisters. The tool came through like a champ.
All’s well that ends well, however. My niece and I had a great time planting beans.

Tomorrow I’ll show you what else we planted. This small suburban backyard will never be the same.