Can coffee grounds repel mosquitoes? This summer, this piece of trivia became a trending topic on Weibo, sparking heated discussions among netizens who are troubled by mosquitoes.
■ Weibo screenshot
However, other netizens soon reminded: Although coffee grounds repel mosquitoes, they attract cockroaches!
■Webpage screenshot
So, is the method of reusing coffee grounds reliable? What are the possible side effects? Zhou Zaojun will explain clearly to everyone the "red and black" of coffee grounds this time.
Repelling insects, fertilizing, removing odors... Are coffee grounds really so versatile?
According to a blog post published by the U.S. Environmental Agency (EPA), coffee grounds have the following functions: can be used to dye paper or clothes; can be used to repair furniture; can be rubbed on pets to repel fleas; can be used to remove odors ; Can be used to clean grease.
Starbucks has been promoting the reuse of coffee grounds around the world, because each Starbucks store produces an average of about 10 kilograms of coffee grounds every day, and the coffee grounds are used for public welfare to "benefit others and ourselves." Starbucks has summarized the five uses of coffee grounds, which are to grow plants, remove odors, keep cats away from your garden, wash dishes, and remove dark circles.
Are these methods really useful? Zhou Daojun reviewed some research reports and public reports and summarized their conclusions.
■Picture of dried coffee grounds: Weibo@人间 Treasure Box
★The more feasible uses are as follows★
- Used as fertilizer: Coffee grounds contain large amounts of potassium, nitrogen, magnesium and phosphorus, which are favored by acid-loving plants Favored - blueberry , rose , camellia, azalea , hydrangea , rose flower , lily , Milan, radish , mushrooms, onions, etc.;
- Acidification of soil: According to Oregon The State University study found the pH of used coffee grounds to be between 6.5 and 6.8, and another study said the pH was 6.2. The acid in coffee beans is water-soluble, and it basically blends into your coffee instead of coffee grounds. The weakly acidic ones are safer;
- Remove odor: Coffee grounds have a porous structure, have adsorption capacity like activated carbon, and can also be used in space Exudes the smell of coffee;
- Scrub: The rough texture of coffee grounds can exfoliate and soften the skin, and can be used to make homemade scrub ;
- Remove dark circles: Depending on the brewing method, coffee grounds may have more High content of caffeine , one study pointed out that each gram of coffee grounds contains an average of up to 8.09 mg of caffeine;
- Attracts earthworms: Although many people say that coffee grounds can attract earthworms, some studies have found that earthworms participate in the composting of coffee grounds. Chemical substances released during the decomposition of coffee grounds must be used after decomposition;
★These uses are less feasible★
- repel molluscs: Some gardeners claim that used coffee grounds can repel slugs And snails, Lewis Spencer, a coffee expert at Coffee Direct, believes that this is because molluscs avoid coffee with a rough surface, but some people have done experiments and found that coffee grounds cannot slow down the traveling speed of snails at all;
- Repel Cats: Cats are a A magical creature that may or may not like the taste of coffee.
More importantly, reusing coffee grounds may not be as simple as you think, and improper handling may have counterproductive effects .
- is not dried: coffee grounds need to be dried when used to repel insects and remove odors. If not dried, they will become moldy. They must be replaced in time when exposed to rain or watering;
- is not decomposed: coffee grounds need to be fermented when used for fertilization, or with As part of compost, otherwise it will become moldy and grow white hair, and even become a home for flying insects;
■Webpage screenshot
- is useless to plants: coffee fertilizer is suitable for acid-loving plants, but not suitable for alkali-loving plants, such as tomatoes;
- leaves too much coffee behind Cause: You may not believe it, but many studies have shown that caffeine uptakes nitrogen from the soil and inhibits plant growth. Applying used coffee grounds directly to the soil is harmful to plant health, especially seed germination and early plant growth.
Turn coffee grounds into treasure, the method is very important
Having said so much, there is only one key. To turn coffee grounds into valuables, be sure to follow the experts’ advice and don’t do whatever you want.
. Insect repellent
You can put the coffee grounds in a bowl and burn them like mosquito coils; you can also use the leaching solution of the coffee grounds. According to previous media reports, at the National Taiwan University Experimental Farm, the leachate obtained by soaking coffee grounds in a certain proportion of water and stirring for 3 days was sprinkled on the leaves of golden citrus that are susceptible to insect damage. It can reduce leafminer moths from eating by 53%, diluting 50 times the leaching solution can also inhibit anthrax bacteria.
■ National Taiwan University Experimental Farm
If there are cockroaches in your home, coffee grounds may attract their attention (especially wet coffee grounds). This is not because of how delicious the coffee grounds are, but because cockroaches will eat everything, inside the coffee machine. Confined spaces are a paradise for reproduction.
■Picture: Web page screenshot
Someone put some wet coffee grounds into a glass bottle, placed the glass bottle at an angle, and put a paper towel on the mouth of the bottle so that insects could only enter but not get out. Some people knead potatoes, sugar and boric acid into a ball and place it at home to kill cockroaches - they are more attractive to cockroaches than coffee grounds.
■ Picture: Web page screenshot
. Fertilization
Also in the National Taiwan University Experimental Farm, using 10% coffee grounds organic compost in the early growth stage of water spinach seedlings can increase the weight of water spinach by 105%. If 2% coffee grounds are mixed into small Cabbage , the leaf length increases by 13% and the weight increases by 22%. There are 30-40 kinds of common leaf vegetables suitable for organic composting of coffee grounds.
■National Taiwan University Experimental Farm Picture: Nespresso
Lin Shuyi, associate professor of the Department of Landscape Science at National Taiwan University, tells you two key points. First, it takes 3 months for coffee grounds to ferment and mature as organic compost . If untreated coffee grounds are used directly, the dosage should not exceed 2% to avoid high temperature fermentation, secondary products, and changes in pH value that are harmful to crop growth.
■ National Taiwan University Experimental Farm
Second, Do not let the coffee grounds directly contact the roots of the plants . You can dig some holes on the edge of the soil, about five centimeters deep, then put the coffee grounds in, cover them with soil appropriately, and then water them thoroughly. Its fertility will slowly decompose, releasing sufficient nitrogen elements to the plants, promoting vigorous growth of stems and leaves.
Additionally, peer-reviewed research conducted by Washington State University recommends that coffee grounds should make up no more than 20 percent of total compost.
. Remove odor
First, dry or dry the coffee grounds until the coffee grounds become lighter in color and not sticky when touched by hand. Then fill the jar with coffee grounds and place it in the refrigerator or other place where the odor needs to be removed without covering it. Remember to observe the condition of the coffee grounds and replace them promptly when they become wet to prevent spoilage. The good news is that the air-cooled refrigerator does not have such troubles. You can even put wet coffee grounds in the air-cooled refrigerator and they will dry out in a few days.
Why should we care about where our coffee grounds go? According to a report by International Coffee Organization (International Coffee Organization), in 2020, the world will consume about 9.96 million tons of coffee.Each ton of coffee beans will eventually produce approximately 650kg of coffee grounds, and the global production of coffee grounds has reached approximately 6.474 million tons. Decomposed coffee grounds will be released into the atmosphere as a greenhouse gas, with a global warming potential that is 86 times higher than carbon dioxide.
■Coffee grounds
How to keep coffee grounds from being “ground”? Each of us has something to contribute.
References
.Rural Sprout:5 Reasons You Should NEVER Use Coffee Grounds In Your Garden https://www.ruralsprout.com/coffee-grounds-in-the-garden/
.Treehugger: Are Coffee Grounds Good for Plants? https://www.treehugger.com/are-coffee-grounds-good-for-plants-5116313
- . Planting vegetables with coffee grounds has high yield, and field studies have found that it can also repel insects and inhibit bacteria https://udn.com/news/ story/7266/6180932
- .Hardgrove, Sarah J., and Stephen J. Livesley. "Applying Spent Coffee Grounds Directly to Urban Agriculture Soils Greatly Reduces Plant Growth." .Evaluation of three composting systems for the management of spent coffee grounds https: //www.sciencedirect.com/science/article/abs/pii/S0960852411007589?via%3Dihub
