I'd guesstimate it would be a good amendment for the soil as well as for concrete!
coffee grounds biochar
coffee grounds biochar
Coffee Grounds Biochar
- Thread starter BeccaBuds
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- #3
Maybe that's why it works with concrete. 
I don't know too many gardeners that have a 660F Vacuum Oven to cook some up in so we can find out... so I'll just get my commercial variety at the Lowes garden shop or Amazon.
I don't know too many gardeners that have a 660F Vacuum Oven to cook some up in so we can find out... so I'll just get my commercial variety at the Lowes garden shop or Amazon.
They grounds should have the acidity dropped down to reasonable levels for use with plants as part of the coffee brewing process. Then turning all the used coffee grounds into biochar and using some for gardening starts to sound like a win-win situation.
lots of gardeners add used coffee grounds to the soil. we do here. increased acidity is one of the noted drawbacks. it's not like you see it in any supersoil recipe.
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- #6
I'm not a composter myself, but I've heard of people composting coffee grounds too. You can always add lime to sweeten the soil if it needs it.
I make my own biochar in small batches. The process reduces the material to essentially its carbon skeleton if done properly so I wouldn't think there would be much impact on the mix from it, though I've never measured pH of my various materials. All the volatiles get burned off in the process so it should be pretty neutral, though it does need to be charged before using or it will suck nutrients from your mix before it begins to add good things to your grow.
One thing that has a big effect on trying to figure this acidity thing is how the word "coffee" is used. We can say we are going out to buy coffee but are we talking about buying a can of coffee to brew a cup of coffee with a coffee pot on the stove? The can of coffee is filled with coffee grounds but after brewing we turned water into coffee and the grounds are still coffee grounds but will not make a cup of coffee similar to what was done just minutes earlier. Or, are we going out to buy a cup of coffee and skipping all the rest?
.I planned on running a few questions past Mr Google to see what turned up by who and from where. The basic question was "how acidic is fresh coffee grounds" and most of the explanations were there in the page of suggested links that showed up.
No increased acidity so not considered a problem.
Fresh coffee grounds tend to be mildly acidic. And, it is a mildly acidic situation. Heat up water and mix in the fresh coffee grounds and the water becomes brewed coffee. That cup of brewed coffee is acidic which might be what makes it a popular drink. And it is possible that the level of acidity may be more than the pH level of acid found in the fresh grounds. But, I did not chase that rabbit down its rabbit hole.
When boiling water goes through the fresh coffee grounds we end up with the cup of coffee and the used coffee grounds are no longer acidic. They lost the acid and have become very close to a neutral pH ranging from 6.5 to 6.8. Tossing the used grounds on top of the compost pile or mixing into the soil will not cause anything to turn more acidic.
Used coffee grounds do have some Nitrogen in them. The nitrogen amounts that I found would range from a low of 1 up to NPK rates of 2.1-0.3-0.3 so there is some benefits there though they are not much. Plus some traces of other nutrients such as calcium, iron and magnesium.
I would not add used coffee grounds to any 'supersoil' mix that I was putting together. Not because they are bad but because it would not be the worth the effort. Better off spending the time and energy adding fertilizing amendments that have higher amounts of what is needed. I am thinking that because of the low amounts of nutrients it is more worhtwhile to toss the grounds around the vegetable and flower gardens or on top of the compost heap.
One thing that has a big effect on trying to figure this acidity thing is how the word "coffee" is used. We can say we are going out to buy coffee but are we talking about buying a can of coffee to brew a cup of coffee with a coffee pot on the stove? The can of coffee is filled with coffee grounds but after brewing we turned water into coffee and the grounds are still coffee grounds but will not make a cup of coffee similar to what was done just minutes earlier. Or, are we going out to buy a cup of coffee and skipping all the rest?
I planned on running a few questions past Mr Google to see what turned up by who and from where. The basic question was "how acidic is fresh coffee grounds" and most of the explanations were there in the page of suggested links that showed up.
No increased acidity so not considered a problem.
Fresh coffee grounds tend to be mildly acidic. And, it is a mildly acidic situation. Heat up water and mix in the fresh coffee grounds and the water becomes brewed coffee. That cup of brewed coffee is acidic which might be what makes it a popular drink. And it is possible that the level of acidity may be more than the pH level of acid found in the fresh grounds. But, I did not chase that rabbit down its rabbit hole.
When boiling water goes through the fresh coffee grounds we end up with the cup of coffee and the used coffee grounds are no longer acidic. They lost the acid and have become very close to a neutral pH ranging from 6.5 to 6.8. Tossing the used grounds on top of the compost pile or mixing into the soil will not cause anything to turn more acidic.
Used coffee grounds do have some Nitrogen in them. The nitrogen amounts that I found would range from a low of 1 up to NPK rates of 2.1-0.3-0.3 so there is some benefits there though they are not much. Plus some traces of other nutrients such as calcium, iron and magnesium.
I would not add used coffee grounds to any 'supersoil' mix that I was putting together. Not because they are bad but because it would not be the worth the effort. Better off spending the time and energy adding fertilizing amendments that have higher amounts of what is needed. I am thinking that because of the low amounts of nutrients it is more worhtwhile to toss the grounds around the vegetable and flower gardens or on top of the compost heap.
you can run a slurry test with used coffee grounds. it will always come back acidic. you can't get around it. it's still usable, it just leaches. most will come down to a neutral range near a ph of 7, just a bit higher than where we work with it.
I went by what appears to be the testing done by the Oregon State University. I did find what appears to be an informative article from the OSU Newsroom which helps handle press relations, media relations and basic communications. While poking around the web with Mr. Google I came across articles from gardening clubs and associations, clubs, and blogs that referred back to the studies that the campus communications article was talking about.
Reading several of them and I get the feeling that there were more than one study done on "coffee grounds and pH". But I did not chase down any of the actual released study results or how many would have been done. I was satisfied with the basic information that the communications article had.
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Our daughter keeps bringing over the used grounds from work and I am running out of garden areas that have already received their fair share. So far everything looks like it is growing properly so maybe I will start to scatter them across the lawn.
Reading several of them and I get the feeling that there were more than one study done on "coffee grounds and pH". But I did not chase down any of the actual released study results or how many would have been done. I was satisfied with the basic information that the communications article had.
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The water used in the slurry test might be stripping some of the remaining acidity from the grounds just like brewing a cup of coffee makes the morning drink acidic and at the same time is reducing the acidity of the grounds themselves.
Our daughter keeps bringing over the used grounds from work and I am running out of garden areas that have already received their fair share. So far everything looks like it is growing properly so maybe I will start to scatter them across the lawn.
my folks keep mixing them with eggshells. the potassium also helps negate acidity as it breaks down. coffee grounds are supposed to be ok for aeration as well.
edit : burning the grounds in to the bio char may concentrate what is there as burning most things generally does.
Again, done properly, biochar anything is pure carbon so shouldn't have any concentrations of anything. Only downside would be adding it to your soil without charging it first as then it would act like a filter and suck up available nutrients until it got saturated.
