Climate-resilient Gardening

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.

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.

How to adapt your garden to climate change

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The news is filled with references to global warming and climate change. In fact, 99% of scientists agree that climate change is real with negative impacts on the environment, weather, human health, and agriculture. In Maryland, climate change is already causing higher average temperatures, more drought, longer heat waves, more intense storms, and flooding. 

So what can we do as gardeners to help the cause and help our gardens adapt to these changes?

Adopt sustainable practices. Environmentally smart practices build climate-resilient gardens and can slow future warming by reducing emissions and boosting carbon in soil and plants. Here are a few ways to get started:

Plant more trees

Trees filter air and water and are carbon sinks, capturing and storing carbon dioxide, a key greenhouse gas. When placed well, trees can save up to 30 percent on heating and cooling costs.  

  • Plant deciduous trees on the west, east or southwest side of your home to block summer sun then let it in to warm your home in winter. Site evergreens to the northwest to buffer winter winds. 
  • Lean toward native trees. They’re well-adapted and need less water and fertilizer, the manufacture of which can contribute to greenhouse gases.  

Add or nurture native plants

Native plants such as this chokeberry and golden ragwort support wildlife and build climate resilience.
Native plants such as these purple coneflowers are pest- and disease-resistant and help build climate resilience.

Don’t stop with trees. Native shrubs, perennials, grasses, and groundcovers also help build a climate-resilient landscape. Native plants, once established, require less water and fertilizer, help store carbon, and reduce soil erosion. Since they co-evolved, native plants best support native pollinators and beneficial insects which provide chemical-free pest control. 

HGIC Website: Native Plants and Climate Change

Keep it diverse

Plant diversity also boosts resistance to pests and disease, so add many different types of plants to your gardens. Yes, more is better. 

Save the soil

Washington County Master Gardener Gary Stallings turns compost, a tool in building soil health and climate resilience

Great gardens grow from the ground up. So protect and improve your soil which stores massive amounts of carbon as carbon dioxide and organic matter.  

  • Keep soil covered since bare soil invites problems. Soil covered with plants, mulch, or cover crops best stores carbon, resists erosion, holds moisture, and has more even temperatures. 
  • Minimize soil disturbance from digging and tilling which speeds up the loss of organic matter and disturbs the soil community.  
  • Recycle nutrients by making and using compost. Compost adds organic matter, helps soil hold water and nutrients, and reduces the need for fertilizers. 

HGIC Website: Improve Soil Health for a Climate-Resilient Garden

Water wisely

  • Save water to make your garden more climate-resilient. Use a rain barrel or create a rain garden to capture and filter rainwater.  
  • Water when plants need it, not on a fixed schedule. And plant in the spring or fall when plants need less water to become established.

A few more tips:

  • Limit the emissions that contribute to greenhouse gases. Use gas-powered mowers, trimmers, and other equipment less and opt for alternatives. 
  • Shrink your lawn and replace it with groundcovers and other alternatives which need less water, mowing, herbicides, and fertilizer. When you do fertilize, do it based on a soil test to use only what you need. 
  • Help more by growing some of your own food or supporting local growers to cut down on emissions from long-distance transportation. 

You can make your garden more climate-resilient. Start with a few steps and build on them to help your garden successfully adapt to climate change.   

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension. This article was previously published by Herald-Mail Media. Read more by Annette.

This article was previously published by Herald-Mail Media.

Maryland gardeners are adapting to climate change

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How are Maryland gardeners adapting their gardens and green spaces to climate change? We posed this question to our colleagues in the University of Maryland College of Agriculture and Natural Resources and several of them shared examples of everything from composting and food gardening to planting trees and native plants, installing rain gardens, and more.

Action on climate change is needed on a large scale, and our individual actions at home and in our communities all add up too. Check out our Story Map showcasing the variety of ways Marylanders are adapting their green spaces with climate change and sustainability in mind. Then take our quick poll at the end of the Story Map and let us know: Are you doing climate-resilient gardening?

Screen shot of the climate-resilient gardening story map

View the Story Map

Learn more:

By Christa K. Carignan, Coordinator, Digital Horticulture Education, University of Maryland Extension Home & Garden Information Center. Read more posts by Christa.

Pollination of Vegetable Crops in a Warming Climate

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Pollination is the movement of pollen from male to female flower parts of sexually reproducing plants. It is often accomplished by wind and insects and results in the development of some type of fruit containing seeds for the species’ continuation. Farmers and gardeners in the mid-Atlantic are finding that high day and evening temperatures can cause vegetable plants to drop flowers and small fruits or produce deformed and under-sized fruits. This  problem has been observed in crops like bean, tomato, and pepper (mostly self-fertile; individual flowers can pollinate themselves), and in crops like squash and pumpkin (require cross-pollination between flowers).

How do high temperatures affect pollination?

All fruiting plants have an optimal temperature range for the pollination/fertilization process. High temperatures can reduce pollen production, prevent anthers from releasing pollen, kill pollen outright, and interfere with the pollen tubes that serve as conduits for uniting sperm cells and eggs (fertilization) inside undeveloped seeds (ovules). High temperatures can even injure flowers before they open. Night temperatures are increasing at a faster rate than day temperatures as a result of climate change, and seem to be most responsible for these pollination problems.

pollination of a flower
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