Mulch piles undoubtedly are virtuous. But we seem to feed ours way too often.

A nice supply of mulch is good for soothing the guilt over wasting food. When, for example, we buy a bag of lettuce and, a week or so later, it has turned into something dark and slimy and about to morph into an entirely different life form, we can ease our consciences with the fact that it will make great mulch.

Our refrigerator and cupboards are often home to other alien substances. The cheese bin usually is full of blue cheese. I love blue cheese, but most our blue cheese started life as provolone or cheddar.

We have loaves of bread that have turned dark green and fuzzy, or have taken on the characteristics of plywood. Crackers, by contrast, have become soft and pliable.

I have bitten into chocolate bars that have sat in a drawer for a while, and watched as worms emerged from the interior.

I have given “aged beef” a bad name. Old pieces of meat have become so pungent that even the dog isn’t interested.

Some of this goes into the mulch pile. Some down the disposal. Some immediately into the trash barrel in the alley.

That is the case even though I usually am vigilant about using leftovers. Nonetheless, I find that we waste a lot of food.

And apparently we aren’t alone.

A recent report by the Natural Resources Defense Council states that an average American family of four squanders $2,275 in food each year, or 20 pounds per person per month.

In all, Americans throw out about 40 percent of the nation’s food supply every year. This amounts to a $165 billion pile of uneaten food, enough to feed several small nations.

Predictably, the U.S. wastes more food than the rest of the world. We send 10 times as much food to the landfill as Southeast Asian countries do.

Part of the reason has to be that so much easily available food is produced in the United States. And, of course, we have ways to safely store it – at least for a while.

If we had to go to a farmers market to buy the food we needed for a single day, the pile of wasted food would shrink. Instead, our inclination is to stock up on food we’ll probably never use.

I have a bad habit of buying food on sale and throwing it into the freezer. I found meat in the freezer the other day that had been there so long I couldn’t recognize what animal it came from. Once I had scraped off the ice crystals, I saw a “use by” sticker dated four years ago.

Americans also might buy more food than they need in part because we are constantly bombarded by ads trying to sell us luscious-looking comestibles. And we buy the large size because it’s more economical or we buy one, get one free, even if we don’t need two.

Portion sizes also have expanded – along with our waistlines. We go exclusively to restaurants that give us more than we can eat. Then we take home the leftovers, put them in the fridge and throw them away a week later.

The report by the Natural Resources Defense Council also noted that Americans are spoiled by perfect-looking produce. If a carrot is crooked or a potato has a protuberance, we won’t buy it.

The study asks Americans to consider buying more ugly fruits and vegetables. It also urges companies to look for alternatives in their supply chain, such as making “baby” carrots out of big carrots orphaned because they are too deformed for the produce stand.

Resources other than food also are wasted, the report notes. Producing food that ultimately is thrown out uses up a quarter of all fresh water consumed in the United States along with 4 percent of the oil, while producing 23 percent of the ozone-causing methane emissions.

While the supply chain might be responsible for much of the waste, excess food is produced because consumers demand it. Thus, if we were a little more careful about how much food we buy, maybe we could reduce the size of the pile in the landfill.

Make a shopping list, and stick to it. Don’t go to the grocery store when you’re hungry. Don’t buy stuff you don’t need just because it’s on sale.

And remember, leaves and grass cuttings make great mulch. You don’t have to rely on rotting lettuce.