Here on the front range of the Rocky Mountains, we have alkaline clay soil that ranges from tan to brown in color. I can jump up and down on the blade of a shovel and not make a dent. I use a thrift store knife to cut weeds off at the root, and I have broken two- snapped the blade clean off in the hard soil.
Except in places where I have mulched.
In shrub beds around the yard where I have been piling leaves and wood chips, I can slice into the soil like it was chocolate cake. Well, maybe brownies.
The best explanation for what happens when we add organic matter to soil that I have read is from Mel Bartholomew’s Square Foot Gardening. Imagine sandy soil is a jar of marbles, water just pours through, moistening the marbles, but not staying in the gaps. Organic matter works like little sponges in between the marbles, holding onto the water and nutrients. Imagine clay soil is like a pile pf playing cards. Water sits on top in a puddle, slowly sinking in. Organic matter works like little sponges in between the cards, creating space for water and air.
So, if you want to build soil, and believe me, you do, here are some ways to do it:
Compost– My favorite compost bin is one that has no bottom, and can be moved around the yard. Every six months or so, I put my bin under another tree, or next to a bush, and when I dump out coffee grounds and orange peels, I enrich the soil in that space. When the bin is full, I move it to a new location, spread out the pile, and have automatic mulch in that zone.
Leaves– I have two big ash trees- they drop copious leaves which I sweep off the patio and rake onto my asparagus, and raspberries, and strawberries, and veggie beds. You may not live in a neighborhood with big trees- some cities have leaf exchange sites where people who don’t want leaves can get rid of them. A few years ago, I participated, and a man brought over a flat bed trailer with a mix of leaves and fresh cut grass. It was heating up as we unloaded the trailer and I spread it around. It made lovely mulch.
Wood chips– I get a pick-up load of wood chips pretty much every year. The goal is mostly to keep weeds down and hold moisture in the soil, but they slowly break down to build soil as well.
– I am lazy about “putting the garden to bed” because I know that the stems and leaves of the plants themselves will break down into soil. Weeds with seed heads I usually throw away, although I don’t get all of them. I intentionally leave some seed heads, like for coneflower or sunflowers, for the birds to eat. Tall stems also catch blowing snow and leaves around them so they act as tiny snow fences.
So, whether you have sandy soil or clay, your garden can benefit from adding organic matter to it. This is a great time of year to begin a garden- pile up leaves and let the worms and other critters turn them into soil for next spring.
Rabbit Hole Warning: See CL Fornari’s You Can Grow that site for more ideas of what you can do, no matter where you live.