Climate Change

Composting and Climate Change

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Composting is probably seen by most people as good for gardens and the environment. After all, compost helps make our soils and plants healthier and keeps green waste from our yards and kitchens out of landfills.

But is composting good in the context of our climate crisis? Doesn’t the composting process generate lots of carbon dioxide (CO2), the principal greenhouse gas (GHG) that traps heat in Earth’s atmosphere? Can composting also mitigate climate change and make our yards and landscapes more climate-resilient? The answer to both questions is YES. This article will show that composting, at the home, community, and municipal/commercial level, is an important global warming mitigation and adaptation tool. As we’ll see, the ways that humans manage this natural process and use the compost can affect the climate benefits.

Composting basics

We don’t make compost! Huge populations of microorganisms do most of the work and we humans manage the process for our benefit. It’s nature’s way of recycling anything that lives and dies, like plants, animals, and microbes.

The decomposition process produces lots of carbon dioxide (CO2), part of the world’s carbon cycling system shown in this graphic:

illustration of the carbon cycle - plants use carbon dioxide from the air and water from the soil to build carbohydrates
Plants exude carbohydrates through their roots to feed soil organisms. Those organisms release carbon dioxide through respiration. Illustration by Jocelyn Lavallee, Ph.D., Soil Scientist

This CO2 release is considered biogenic (happens through natural biological systems), not anthropogenic (people-made), and is not included in the calculations of greenhouse gas (GHG) emissions that drive global warming and climate change.

The three primary GHGs are:

  • Carbon dioxide (CO2) — 300-1,000 year atmospheric lifetime; 86% of total GHG emissions
  • Methane (CH4) — 84X the global warming potential of CO2; 12 year atmospheric lifetime; 7% of total GHG emissions
  • Nitrous oxide (NO2) — 265X the global warming potential of CO2; 100 year atmospheric lifetime; 6% of total GHG emissions

There are many factors that determine the potential for composting to generate methane and nitrous oxide, like the mix of materials being composted, temperature, moisture, pile size and configuration, and aeration. Compost piles and windrows that are waterlogged and low in oxygen (anaerobic) are more likely to generate these GHGs. Composting is “climate-friendly” when it’s done in the presence of air (aerobic). Home and community composters turn piles by hand to keep them aerated and large-scale composting facilities use mechanical turners and force air into windrows with blowers. Well-managed composting at any scale releases very little methane or nitrous oxide into the atmosphere. 

Direct climate benefits of composting

  • Dumping food wastes and grass clippings in landfills generates large amounts of methane because the decomposition process is anaerobic. Landfills release about 17% of total U.S. anthropogenic methane emissions and food waste makes up 24% of landfill space. Burning organic wastes releases GHGs and toxins. Composting these organic wastes using best practices greatly reduces emissions.
  • Carbon sequestration: Compost continues to degrade after soil incorporation. Some of the carbon cycles through soil microorganisms and some is held tightly to clay particles, protected against decomposition, and becomes part of the long-term reserve of stored carbon.

Indirect climate benefits of composting

The mid-Atlantic climate is becoming wetter and warmer overall, punctuated by localized extreme weather events, like record-breaking rainfall and extreme drought and heat. Intense storms can cause soils and nutrients to wash away and warmer temperatures cause more rapid organic matter decomposition and turnover, especially if soils are tilled and uncovered.

Adding compost to soils makes them more resilient by:

  • Holding more water in the soil during periods of drought and extreme heat
  • Reducing erosion (washing away of soil during extreme rainfall) and nutrient run-off) due to improved soil structure (larger, more stable aggregates or crumbs)
  • Improving plant growth, by slow release of plant-available nutrients
  • Reducing the need for synthetic nitrogen fertilizers which require natural gas for their production
  • Reducing the need for potassium and phosphorous fertilizers (derived from mined mineral deposits that are dwindling worldwide)
  • Binding and degrading toxic metals and pollutants
  • Substituting compost for peat products can help reduce the release of CO2 from commercial peat extraction from wetlands 
illustration of how compost combats climate change - increases water holding capacity - sequesters carbon in soil
Poster by the Institute for Local Self-Reliance

Home composting

Managing and recycling as much yard waste as possible on-site is often the most climate-friendly approach because it reduces GHG emissions from transporting and processing or landfilling organic waste. You can do this by recycling grass clipping (“mow ‘em high and let ‘em lie”), mulch-mowing tree leaves and leaving them in place, or using them as mulch, composting yard and garden waste, and burying kitchen scraps. These practices help to recycle nutrients on-site and increase soil organic matter. Selecting or building a non-plastic composter can also help reduce GHG emissions.

Municipal/commercial composting

This is the next best option for organic wastes that cannot be managed on-site. Commercial and municipal composting operations do create GHG emissions from the trucks and equipment, powered by fossil fuels, that are used to collect, transport, and process organic waste and compost. The closer the source of organic waste to the facility the lower the emissions and the greater the benefits. On balance, composting on a large scale can also help mitigate climate change.

illustration showing that the carbon sequestration benefits of municipal composting outweigh the greenhouse gases generated by transportation, storage, and processing compost

To summarize: aerobic composting reduces GHG emissions compared to the landfilling and incineration of organic wastes. The resulting compost sequesters carbon when mixed into soils and improves soil health and resiliency. Composting at home and in your community is the most climate-friendly approach but commercial and municipal composting is another important tool that helps mitigate climate change.

References

By Jon Traunfeld, Extension Specialist, University of Maryland Extension, Home & Garden Information Center. Read more posts by Jon.

Vegetable Problems Update

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Wildfire smoke

Persistent wildfire smoke is new for Maryland gardeners. Experts seem to agree that smoke and ash do not pose a health risk for garden produce. Smoke diffuses sunlight but will probably not significantly reduce the total amount of light for photosynthesis. We have not heard/seen any reports of gardeners picking up smoky flavors in harvested greens or other vegetables or fruits.

  • Wash all produce prior to eating it raw or cooking with it
  • Wear an N-95 quality mask when working outside on days when wildfire smoke worsens air quality
  • Hose off plants if a noticeable soot layer develops from prolonged, intense smoke

Wildfire smoke has been shown to boost the levels of ozone and other air pollutants which can injure plants. Watermelon, squash, pumpkin, beans, and potato are especially vulnerable to high ozone levels (above 75 ppb).

Drought and damaging storms

Wildfire smoke interfered with weather patterns and likely contributed to cooler and drier weather across much of the state. 

Mid-May through June:

  • Lower average temperatures
  • 75% of state in moderate drought on July 3rd
  • Slow start for warm-season crops

July:

  • High heat and humidity
  • Spotty rainfall
  • Insect and disease issues increasing
Maryland drought status map
The Maryland Department of the Environment announced a Drought Watch on July 10, encouraging voluntary reduction in residential water use.
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Plant shopping soon? Avoid buying invasive plants

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It’s a sunny day in late February and that means I’m looking at seed catalogs and dreaming of new plants! Have you been plant shopping yet this year? Adding new plants and seeds to your garden creates new scents, textures, colors, and shapes and is the easiest way to increase biodiversity in your landscape!  

As you begin revitalizing your garden space this spring, I want to bring some attention to invasive plants, a category of plants that should strike fear and dread in your heart! Okay, maybe that’s a bit dramatic, but truly this is a topic that everyone needs to learn more about. 

Q. What is an invasive plant?

A. An invasive plant is a non-native, “alien” species that was introduced intentionally or by accident into the landscape and causes ecological and/or economic harm. These plants tend to be free from predators, parasites, and diseases that could help keep them in check. These plants reproduce rapidly with multiple methods (i.e. seeds, stolons, root cuttings, runners, etc.) and spread aggressively. They tend to be deer resistant or deer tolerant, a big reason why they are purchased and planted in landscapes. Below is a photo of purple loosestrife. Notice how it is creating a monoculture, a visual key that might mean the plant is “invasive.”

purple loosestrife flowers crowding a field
Invasive purple loosestrife (Lythrum salicaria).
Photo: Richard Gardner, Bugwood.org

Did you know that some invasives are still for sale at nurseries, greenhouses, and in mail-order catalogs?   

It’s true. Many of the plants on “watch lists” are still readily available to purchase. Japanese barberry is an invasive plant that is a very popular landscape plant still being widely planted today; however, research shows that black legged ticks have been found in areas with invasive barberry thickets because these non-native, invasive forest shrub thickets create ideal microclimates.   

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Centering vegetables

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In the days after Thanksgiving, I was casting around for something to write about in this blog post, when my husband surprised me at dinner with this masterpiece:

(From a Washington Post recipe; he used pine nuts instead of almonds because that’s what we had.) 

So I began to think about the idea of vegetables as centerpieces for the table. We are not vegetarians and this meal did include meat, but it was off to the side, not the focus of attention. Now, anyone who reads my posts here knows I love growing, cooking, and eating vegetables. When I go out to a restaurant, the kind where vegetables aren’t “sides” but a part of a constructed meal, I generally read the menu descriptions backwards and often choose the entree I’m ordering based on the vegetable accompaniment, deciding that I’m in the mood for parsnip puree or butternut squash risotto and that delicious-sounding salsa, and only afterwards acknowledging that the meat it comes with is just fine. (I’m also a sucker for unusual produce; I once ordered a meal at a restaurant in Oregon that was… probably fish? I don’t recall, but what sticks with me is asking the waiter what sea beans were, and when he was unsure, placing the order anyway and then pulling out my phone to search. They were great; can’t grow them here, alas, because they require a salty environment.)

But the point of those restaurant meals, and most of the ones we eat at home, is that the meat is in the middle. Even many vegetarian meals center a protein element that explicitly substitutes for meat, from plant-based burgers to Thanksgiving Tofurky. Many meals don’t, of course; pasta, pizza, and stir-fries are a few of many examples that combine elements from different food groups. But don’t we tend to describe them in terms of the protein, unless they’re a side dish themselves? How often do we talk about, yum, that dish I made with Chinese broccoli and those wonderful little peppers, oh and by the way I also put in chicken?

I think this is very much a cultural thing, and this is not the place to try tracing it through American history and sociology and noting the influences of and changes in various immigrant communities. I also don’t have the expertise to tell you exactly how much protein you need in your diet based on what food choices you make, and where you can find that protein. I do know, however, that it’s possible to eat healthily while thinking of meals in the way we’ve come to consider inside-out, that is with the vegetables first. This doesn’t have to involve spectacular centerpieces that take hours to cook; the pumpkin stuffed with onion, apple, fennel and cornbread, with maybe a little bacon for fun, can be relegated to the big holiday meal. But vegetables can at least be first in our meal planning part of the time. Maybe even all of the time.

Tamar Haspel, who writes for the Washington Post about larger perspectives having to do with diet, had a recent article about which plant foods are most and least impactful on our climate. (All plant foods are usually better climate choices than meat.) She concluded that fruit, nuts, and row crops such as grains and beans are better in an environmental sense than vegetables like lettuce, broccoli, and tomatoes, because the latter use more fertilizer and pesticides, go bad quicker and so contribute more to food waste, and provide fewer calories per acre. What this doesn’t account for, of course, is growing your own. Your home-grown veggies have zero crop transportation costs, and you will likely be using a lot less in the way of inputs. So I think you can eliminate climate guilt from the equation if you plant a garden. (Buying locally-grown produce would be the next best option.)

What are the best crops to grow if you’re trying to center vegetables on your table? Anything you like and will eat, basically, but if you’re going for the big centerpiece, think about squash or peppers that can be stuffed, beefsteak tomatoes (especially colorful heirloom types), or indeed cauliflower, though you’ll have to keep up with the fertilizer and water to achieve big, fully-formed heads, especially for a spring crop. Also think about ingredients you’d like to add to savory pies, galettes, or other pastries, or quiches and frittatas, or casseroles. Greens make a great base for many other dishes, or can star on their own mixed in with pasta or grains. And there’s always a big salad filled with lettuce, arugula, herbs, cucumbers, etc. – oh, and maybe some meat or fish too.

I’m still trying to shift my thinking from saying, when making meal plans, “We’ll have pork chops and…” “We’ll have macaroni and cheese and…” to a vegetable-centered focus. Here is a big lovely winter squash, I might think—what meat goes with that? Or maybe cheese and nuts? Can they go inside? Those Yellow Cabbage Collards I grew and put in the freezer: great with a little ham and a high-protein grain. I mean, sometimes we’ll just want a steak and potatoes with the greens on the side, but it’s worth doing the vegetable mind trick several days a week. And when there’s a little leftover steak, it might add something to a stir-fry of broccoli and beans.

If you’re looking for recipes, either search online for the vegetable you want to feature and “main dish,” or use a cookbook, vegetarian or not, that makes vegetables or vegetable families one of its primary organizing principles. And when you’re browsing the seed catalogs that are starting to arrive, consider what you might like to grow next year that will feature as the center of your table.

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.

Food waste reduction: It’s everyone’s job!

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Our society wastes food at every point in the food chain from farms and gardens to home kitchens, restaurants, supermarkets, food service companies, and large institutions like universities that feed  thousands of people daily. Last December I was astonished to lean about the extent of food waste at the MD Food Recovery Summit organized by the Maryland Department of the Environment. 

Surplus food is the term used to describe unsold and unused food, like crops that don’t go to market because prices are too low, perishable items tossed into supermarket dumpsters, and groceries and restaurant meals bought and not eaten. 

In 2019:

  • 35% of all U.S. food went unsold or unused 
  • 23% of all surplus food is fruits and vegetables 
  • Only 15% of Maryland’s 900K+ tons of food waste was recycled 

Why it’s a problem:

  • Huge economic and environmental costs of producing surplus food
  • 1 in 6 U.S. residents are food insecure. Surplus food can feed hungry people
  • Surplus food is the #1 landfill material (24% of landfill space) 
  • Food waste in landfills generates methane, a potent greenhouse gas that can trap 28X as much heat/mass unit as CO2
  • The value of wasted food at the consumer level is $161 billion/year
Compost, recycle, and trash bins
Food scrap collection at Maryland Day event at UM/College Park campus. Photo credit: Jon Traunfeld
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Cover crops for climate-resilient soil: Try it, you might like it

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Cover crops are so important for improving soil and protecting the environment that it’s public policy in Maryland to use federal funding to subsidize farmers to plant them. Nearly ½ a million acres across the state are enrolled in Maryland’s Cover Crop Program. Cover crops protect Maryland’s farm fields from soil loss over the winter and scavenge the soil for the fertilizer nutrients that weren’t used by corn and soybean crops and might have moved into groundwater and surface water. 

Cover crops are typically planted from late August through October and include grasses like winter rye, winter wheat, barley, and oats and legumes like crimson clover and hairy vetch. Plants in the legume family, together with special soil bacteria, transform nitrogen from air into a plant-available form. Tillage radish (a type of daikon radish) and other plants are also grown as cover crops. 

Cover crops improve soil health and help make soils more resilient to the climate crisis. They

  • increase soil organic matter and carbon sequestration by feeding soil microbes with sugars and other root exudates 
  • improve soil structure and the strength of soil aggregates which lowers erosion risks
  • increase water holding capacity which allows crops to withstand drought better   

Cover crops use the sun’s energy (when food crops aren’t growing) to produce biomass- roots, shoots, and leaves. The cover crops are killed in the spring. Nutrients in the decomposing plants are eventually available for uptake by the roots of the vegetables and flowers we plant. This reduces the need for synthetic fertilizers, whose production requires fossil fuels.

What’s good for ag soils is also good for garden soils! 2022 is the Year of Soil Health for Grow It Eat It, the food gardening program of the UME Master Gardener program. This infographic by Jean Burchfield introduces the idea of planting cover crops, a key practice in building healthy soils: 

Infographic about cover crops

Photo of seed packets
UME Master Gardeners distributed 5,000 crimson clover seed packets for residents to plant in flower and vegetable beds this fall.
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Diggin’ into plant-based diets

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As gardeners, one of the many actions we can do at home to mitigate climate change is to grow and eat some of our own fresh produce. Meat and dairy products account for an estimated 14-16% of global greenhouse gas emissions, according to the UN’s Food and Agricultural Organization. Having a home or community garden gives you access to nutritious foods that can be part of a more plant-based diet — one that’s healthy for you, and the planet! Today’s guest post on this topic is from University of Maryland Extension Family & Consumer Sciences Agent Beverly A. Jackey.

Following a plant-based diet is very trendy these days. Whether it’s an environmental reason (reduce your carbon footprint) or a health goal (decrease the risk of some chronic diseases), many people, including myself are consciously reducing their consumption of animal products.

What does it mean to follow a plant-based diet? That really depends. Some interpret it as being a vegan or vegetarian. Others view a plant-based diet as being broader, including more plant foods, such as fruits, vegetables, and grains, and also fewer animal foods, like meat, fish, and dairy. It’s not necessary to give up all the animal foods you enjoy; however, you can consider decreasing the portion sizes so these foods are no longer the main attraction on your plate. 

Ever since attending a 2019 nutrition conference, I’ve been inspired to consume more plant-based foods. It’s unlikely I will give up my glass of cold, fat-free milk in the evening (with one cookie); however, I do consume at least three meatless meals per week, eat smaller portions of chicken, fish, and lean beef and pork, and I load up half of my plate with vegetables (see my grilled vegetable recipe). This summer, my deck garden provided enough delicious red tomatoes to enjoy almost every day on salads. Since making these changes, I’ve maintained a healthy weight and blood pressure and feel good about doing something for Mother Earth. 

Are you ready to ‘dig in’ and adopt a more plant-based diet? Here are some tips that helped me get started.

  1. Go meatless one day a week. Beans, lentils, and nuts are great sources of plant proteins and add fiber to your diet, which makes you feel full. Instead of adding meat to my pasta, I toss it with grilled vegetables. If you like chili, peruse recipe websites for a bean-based chili that appeals to your taste buds.

  2. Combine vegetable proteins. Quinoa is a perfect protein, meaning it contains the 9 essential amino acids your body needs daily. You can also combine other plant foods to get that perfect protein. Some of my favorite combos are black beans and rice, chickpeas and pasta, and whole wheat bread and peanut butter (with some jelly).

  3. Re-think your meat portions. You can still have meat at your meals, but in smaller amounts, like 3 cooked ounces (the size and thickness of a deck of cards). Many meals like soups (winter) and salads (summer) are full of vegetables and whole grains, but I add a small piece of protein, like a leftover grilled and shredded chicken breast or a few slices of pork tenderloin.

Try this recipe for Easy Grilled Vegetables!

Selection of vegetables:

  • Red, yellow, or green peppers – cut in half and seeded
  • Yellow and green squash – sliced length-wise, about ½ inch thick
  • Eggplant – sliced width-wise, about ½ inch thick
  • Mushrooms – whole cleaned
  • Onion – sliced width-wise, about ½ inch thick

Additional ingredients:

  • 1/2 cup olive oil
  • Salt and pepper
  • 4 tablespoons balsamic vinegar
  • 2 teaspoons, minced garlic
  • Fresh chopped or dried herb (parsley, thyme, basil, etc.) for garnish

Instructions:

1. Mix oil, salt, pepper, vinegar, and garlic together.

2. Arrange vegetables on the grill or in a grill pan (medium heat). Note: depending on the size of your pan you may need to work in batches.

3. Grill vegetables for 6-8 minutes, brushing with oil, and vinegar mixture.

4. Remove vegetables from the grill or grill pan and place them on a platter. Drizzle the remaining oil and vinegar mixture on the vegetables. Sprinkle herbs over vegetables and serve.

By Beverly A. Jackey MS, RDN, LDN, Agent, Family & Consumer Sciences, University of Maryland Extension (UME). This article was published originally on the UME Breathing Room blog, which covers topics on health, wellness, nutrition, and financial management.