This column continues our series on sustainability. With people spending a great deal more time in the garden, growing your own food has become a serious enterprise.

One thing any gardener knows is you must continuously amend your soil with compost.

Think of it as homemade fertilizer. When compost is placed on top of existing soil, it adds nutrients, such as carbon and nitrogen, which are used by plants for growth and photosynthesis. It also improves soil structure, which means holding the correct balance of moisture, nutrients and air. It does this by introducing beneficial microorganisms to the soil such as bacteria, fungi and protozoa.

Composting is good for the aina. It also reduces food and garden waste and, in doing so, reduces landfill. It diminishes methane greenhouse gas to the atmosphere and reduces the need for factory-made fertilizers and chemicals.

So, how to get started? One way is to dump your kitchen scraps, grass cuttings, etc., into a rubbish bin. Make sure to drill it full of holes (add some water now and then) and wait for a few months for nature to run its course.

A better way is to acquire a composting tumbler. This is essentially a bin that can be rotated like a cement mixer to aerate your waste concoction.

There is a plethora of them available in the $100-$200 range on Amazon. I settled on the Miracle-Gro Dual Chamber model for a couple of reasons. The first is that Miracle-Gro is a respected name brand, so I figured it is not going to sell junk. Second, my yoga teacher Ray Madigan, who’s a helluva gardener, owns one and recommended it.

The model is a dual-­chamber unit which allows you to “cook” two batches of compost simultaneously. Thus, if you are further along on one, it’s better to add materials to the second chamber so as not to lengthen the process on the first batch.

Assembling the unit took me about an hour. All you need is a large and medium­-size Philips-head screwdriver. The parts snap into place and fit well. You might need a mallet to tap things into place, but it’s fairly well engineered.

There are no assembly instructions that come with the box. Instead they provide a paper slip with a website. The website’s instructions are illustrated but don’t contain text, which I found a bit puzzling. There were links to a how-to video, but they didn’t work. Fortunately, you can find an assembly video posted on YouTube by typing “How to assemble a Miracle-Gro Single Chamber Outdoor Garden Compost Tumbler.”

Once assembled, the tumbler is sturdy. It comes with a solid stand so you can spin the tumblers with confidence. It comes with a brake so that when you’re loading a tumbler, it stays put. The brake is a bit flimsy, but you can live with it. For $100 on Amazon it’s a good deal.

In retrospect I should have chosen a model with larger-capacity tumbler so that I could manufacture more compost. If you have a large garden, you’ll need more compost. As alluded to above, if you have some old rubbish bins, they will take longer to produce compost but will provide extra volume that you might need.

The key thing in making compost is getting the proper balance of “brown” (think dry leaves, coffee grounds, twigs, etc.) and “green” or fresh components (table scraps, grass cuttings and anything rich in nitrogen). Start with about a 50-50 mix and see whether it gets warm. (It’s supposed to.)

Of course, you’ll want to hydrate the mix with the right amount of water to make it damp. (Too much is no good.) And naturally, you’ll need to aerate the mix by tumbling it. If your compost begins to smell like ammonia, add more leaves. What you don’t want to do is add meat or dairy scraps. Chicken manure is good, but no human or dog poop, for sure.

You’re going to have to experiment to get the right formula of brown, green and H2O. You’ll find amending the soil makes a huge difference.

Rob Kay, a Honolulu-based writer, covers technology and sustainability for Tech View and is the creator of fijiguide.com. He can be reached at Robertfredkay@gmail.com.