"What is a biotrash pit?", I've been asked. I have used the term often enough on the blog, so perhaps I need to explain. It's a hole in the ground.....in Hawaiian, a puka.....into which I throw my coarse organic debris. Some of the dips on my farm are big enough to hide a truck or car in, for real! Over the years I've filled a few in then planted bananas. No need to water or fertilize the bananas, ever. Even during drought, the bananas seem to do fine. And since I add a generous layer of coarse mulch seeded with a bit of manure each year, no need to use commercial fertilizer.
My pits are a good place to throw twigs, branches, tree limbs, chunks of tree trunk, dirty cardboard boxes, banana trunks, discarded coconuts, palm fronds and any other large organic matter that will take time to degrade. Plus I throw in lots stuff to fill in the gaps.....just about anything. Weeds, sawdust, dirt, excess manure, old kitty litter, dog poo, paper trash, macnut shells, rotten fruits, pulled out ferns from the pastures, garbage that's too rotted for even the chickens to eat, and just about any and all biodegradable waste.
Above -- It's really difficult to make sense out of this photo, but believe me, this was once a giant hole that easily could have swallowed my truck. I've spent the past several months filling it in with the debris generated by our last wind storm. Lots of leaves, twigs, and tree branches. But also some knarly tree trunk chunks. I would throw in about a two foot thick layer of stuff then squash it down by either tramping all over it or running the ATV over it. Then I add a light covering of soil Inorder to add soil microbes, and add some water to wet it down a tad. If I have them handy, I'll also throw in rocks as I fill the hole,mabout 3 per cubic foot, to add a tad of stability. The reason for the rocks is that I plan to plant banana trees. If the ground is too soft, the trees will simply fall over from the weight of the bananas.
I've thrown pickup truckloads of green waste into this hole. As I said, months worth of clean up. Many layers upon layers. It amazes me just how much green waste it takes to fill up a hole.
As the pit is being filled, I'll add water if needed to keep things lightly moist. This year has seen a lot of rain, so I've been spared the chore of hauling water to the pit. Once the pit is filled, I'll top it off with a light layer of dirt/compost, then apply a couple inches of coarse mulch. Whatever I happen to have handy.....ti leaves, banana leaves, sugar cane waste, bamboo leaves, coarse weeds, guinea grass. It all works as a coarse mulch. I'll now add water to these layers so that everything is moist.
Ah-ha, time to plant bananas! I'll make a hole for each young tree, a hole large enough to hold about a 5 gallon bucket of soil.
Above -- Hole made in the debris. I set the bucket into the hole so you could see it.
The tree gets planted and watered in. Then I'll mulch around it with a 6 inch layer of mulch, such as bamboo leaves or grass clippings. Ta-da. Done! I can now walk away, only to add mulch from time to time to keep the soil covered. Of course, this is a good spot to dispose of my coarse, large leaves. Leaves and stalks from bananas, ti, sugar cane, guinea grass, etc all make good mulching material around the bananas.
The homestead farm is 20 acres. There are lots of good sized pukas on it, so I don't think I'll run out of biotrash pits in my lifetime. I never need to haul any of my green waste to the dump.
One thing I've learned is that all that green waste decomposes over time. Thus the hole sinks. So I initially grossly overfill the hole knowing that it will sink at least 50%. Once I plant the bananas, I continuely add mulch. This helps keep the hole filled in, but not completely. The more tree trunks and limbs used to fill the pit, to slower the sinking process proves to be.