We enjoy the company of coffee in the morning on a daily basis. The morning doesn’t start unless we’ve had a cup of coffee in our system, making us coffee lovers properly function. Coffee has become a daily necessity for some people, and due to this, coffee is used in many other products such as coffee ice cream. Of course, people have experimented on coffee as a fertilizer, giving more nitrogen to your compost, therefore, speeding decomposition. But how does adding coffee grounds affect the soil when added directly? Will this endanger your soil and plants? Are they helpful in the growth of tomatoes, berries, and other fruits and vegetables? Is applying coffee grounds effective or not?
If you look deep enough in the internet, you would be able to find thousands of websites and blog posts that recommend using coffee grounds as a nutrient giver, cat repeller, appeal earthworms to your soil, helps the friendly bacteria, slug repeller, prevent weed infestation, and many more functions that if I mention all of them, we will run out of space to write. However, only a handful of them is accurate and useful while some are just myths that people spread around. To make everyone’s soul be put to rest, we will examine how does coffee affect the soil and the growth of plants.
Using coffee grounds as a compost
If you don’t know, coffee grounds contain 10% nitrogen abundant proteins that are important for seed germination and plant growth. The carbon to nitrogen ratio of these coffee grounds has a minimum of 11:1 that is perfect for the soil. The problem lies in the common myth that coffee grounds are by nature, acidic, it would lower the pH level of the ground, therefore making your soil more acidic that is needed by plants which thrive on acids such as rhododendrons, blueberries, and many more from the Ericaceae family. It is however not proven to be a hundred percent true, and there are still researches conducted about the effect of coffee grounds on the acidity level of soils.
According to recent researches, adding coffee to composts varies in results that range from a mildly acidic fertilizer of 4.6 to an alkaline compost having a pH level of 8.4 which is pretty alarming. Also, in the conducted research, the coffee grounds that were directly added to garden soils have found that there was instability of pH levels of the decomposing properties. However, there was an increase in acidity levels in which the pH level of the soil decreased not too long after the addition of coffee grounds into the compost.
Coffee grounds are, however, yielding positive results when used as a mulch on garden soil. Just like with any other mulch found on the market, they help recede the soil temperature as well as the moisture level in the ground. Using coffee grounds also has a benefit of tethering the pesticide chemicals and other toxic metals that prevents them from spreading through the surrounding environment and keeping the pollutants that heavily damages our waterways. There are also promising results when it comes to increasing essential nutrients that every plant should have such as iron, zinc, and nitrogen. You only have to be careful when it comes to the various pH levels that every coffee bean has, since not every coffee bean has the same acidity levels that are significantly affected by the method of brewing that is used before placing on the soil.
Is it necessary and beneficial to add coffee grounds directly on your garden soil?
If the coffee ground is added straight to the soil, they are broken down by the microbes found locally. Substances such as humus are created when decomposed by the microbes that are significant to increase the quality of the soil regarding nutrients needed by plants. Don’t worry about the coffee grounds applied on top of the soil, as earthworms use this as a food source and therefore they have to pull them deeper into the ground, enhancing the quality of your soil.
Be sure to know the needs of your plant since there are plants that hate abundant nitrogen. Examine carefully what kind of plant you have, understand its basic chemical needs and prevent them from being poisoned by the high nitrogen contained in the coffee grounds.
As mentioned above, coffee grounds help subdues seed germination in most plants while restraining the growth in some. It is due to the highly toxic materials produced the moment that the coffee grounds decompose that could be accountable for the weed suppression that could severely harm your soil. Since there’s still no concrete evidence of these effects, be sure to never add coffee grounds straight into the ground or use this as a compost where seeds are being germinated.
Does coffee grounds control bacteria in the soil?
There have been studies that resulted in coffee grounds restraining fungi and bacteria such as Sclerotinia, Pythium, and many other parasitic oomycotes. In recent researches about controlled conditions on selected plants that use coffee grounds as compost mix, they have shown to be able to prevent some fungi and bacteria in instituting in the soil. These are proven only on beans, tomatoes, cucumbers, and spinaches so be careful when using them on other crops.
With all of the data gathered, we can safely conclude that we could only use a maximum of 20% of coffee grounds on total compost volume and never exceed more than that to prevent any problem arising. The safe threshold of 20% is enough for suppressing bacteria and other parasites that could be found in your soil while not increasing the pH or acidity level of your soil. Take note that the pH levels vary on the ecosystem and environment of your plantation.
It is safe to use coffee grounds as compost but never exceed from the recommended volume since they compact quickly and block air and water pathways. Use them with other organic fertilizer to prevent this problem from arising. Mix coffee grounds with other compost to maximize the result. I hope that you’ll have happy farming after enjoying a cup or two of coffee!