Some things should be kept out of the compost pile

Now is a great time to get your compost established, if you have not done so already. Composting is about the best way to take household garbage and transform it into something that benefits the soil, the plants growing in it and the environment as a whole.

Composting can diminish methane, the potent greenhouse gas that can be a byproduct when biodegradable materials go into the landfill. Compost, whether made in your backyard or purchased from a nursery, is a terrific source of plant nutrients that also helps soil retain water. Here in the Mojave, as we all know, that is an important consideration.

Because it is so simple, and because so many people are composting now, there is a huge range of recipes. We have a few of them at both the Cooperative Extension office and on the website. Composting is basically just mixing together degradable garbage, from lawn clippings to vegetable peelings and coffee grounds, with a larger amount of shredded paper, dried leaves, dryer lint, even sawdust. Bacteria and fungi do the work of degrading that feedstock until it looks like lovely and rich soil.

With worm composting, red wigglers break everything down. The gardener need only provide the raw materials and water, and occasionally turn it, for aeration’s sake.

We do not talk much about what not to put into compost. Eventually, everything does break down but not everything breaks down at a rate that meets our needs. For instance, we tell people not to put meat or meat bones into the mix. Anyone who has watched a crime scene investigation TV show knows that bones do not break down readily. If the compost contains meat or bones, every dog in the neighborhood will be trying to get into it.

We also advise against adding dog or cat droppings. Although manure is full of nutrients for plants, there are too many downsides to using it. Smell, for one thing, and it would attract neighborhood pets for miles around.

Nothing greasy should go into the compost. This includes foods such as mayonnaise and salad dressing, as well as milk, cheese, eggs, butter, lard. These things smell rancid when they have been sitting around for a few days. They also have a tendency to cause parts of the compost pile to go anaerobic. When that happens, you get the whiff of sulfur, or sewage. A foul smell is often the reason people object to composting.

Avoid adding anything animal-based. People often ask me about using eggshells, since these are desirable, even essential for compost in other parts of the country. Although they aren’t bad, they’re more than one-third calcium, and most of that is in the form of calcium carbonate — which you might know is the key ingredient of caliche. You generally do not need to add any more to the soils of Southern Nevada. The calcium deficiencies we see are most often the result of irregular watering.

There are things you might wish that you could compost, but it is better if you do not. Any plant that died with an insect infestation should be bagged and sent to the landfill. The temperatures of the composting process might be high enough to kill off any eggs or larvae, but there is always the chance that some would escape and become a big source of problems when you use the compost in your garden.

The same holds true for diseased plants — powdery mildew or anything like that. Regular composting (not worm composting) generates quite a bit of heat, and there is a good possibility that the process will kill any disease organisms.

Still, who wants to play Russian roulette with their garden? If a plant is diseased, bag it and send it to the dump with the garbage.

Sometimes good healthy plants, or prunings from healthy plants, should not go into the compost, either. Plants such as oleander, for instance. Much as we love it — what else blooms so profusely in the middle of the Mojave summer? — it does contain some compounds that could be dangerous.

If the occasional leaf or twig drops into the compost, that is not a major problem, but avoid putting in large amounts.

As a general rule, be judicious when you add any highly aromatic plant such as cedar and pine. They will break down just fine, but some of these aromatic compounds are plant defenses, to protect it from microorganisms. You really do not want to put in large quantities of antimicrobial agents.

Other than these, you can put almost anything into the pile, and create a pleasant-smelling soil amendment that will nourish your plants and the soil where they grow.

Angela O’Callaghan is the Social Horticulture Specialist for University of Nevada Cooperative Extension. Contact ocallaghana@unce.unr.edu or 702-257-5581.