I have been all over the internet looking for a reliable answer to this question. I have found forums saying it is a brown others saying it is still a green. I have done search after search to find a university study that states what the actual carbon to nitrogen ratio is for dried grass clippings. Everywhere I find the ratio listed for green grass clippings and sometimes implied for dried but not made clear. Example grass clippings 15,20:1. Does that mean green is 15:1 and dried is 20:1 or is that for different varieties of grass for green clippings? I find some places saying grass does not lose much nitrogen as it dries and others showing over 90 percent nitrogen loss during drying. Does anyone have a source for the actual carbon to nitrogen ratio of dried grass clippings?
What is the carbon to nitrogen ratio of dried grass clipping
Since you have searched well, I think nothing exists. Conditions during the drying are going to vary and could make a huge difference. I would think the range stated is because of the nature of nitrogen going away easily and the variability of how much water was in the clippings that were tested etc.
I did find that dried grass clippings are about 3 per cent nitrogen. So if they can state that why not a carbon to nitrogen ratio of the same dried grass clipping? Still looking for the answer. I suppose it is really not that important, but somethimes I just wonder about things. I also found that dried grass clippings lose over 90 per cent of their nitrogen. However at 3 per cent that is still more nitrogen than manure has in it I think.
Never give up! I finally found the carbon to nitrogen ratio for dried grass clippings, 50:1.
I realize that this is a very variable figure but it gives me a good ball park figure to go by, and answers the question should it be a green or a brown. With that carbon to nitrogen ratio, it should be used as a brown, even with the three percent nitrogen.
Also found this nifty compost calculator:
Unfortunately two of my most used ingredients: dried grass clippings and dried shredded leaves are not included, but I still find it interesting and a good general guide.
This site has lots of info about composting:
That calculator is fantastic. I've never come across one. It will make it really easy for me to better visualize the proportions I need. Have to guesstimate on the shredded leaves. Depending on the type of leaves, I think shredded could have 2-3 - ? times as much carbon mass as loose.
I just read the Wood Chip Backyard Biology page. One of the most clearly written concise I have read on that subject. A++.
This message was edited Feb 23, 2013 11:26 AM
Check out the "Links to Compost and Organics Information" at the bottom of that page lots more good stuff about composting!
Hay- that is sort of a dried grass, right? That is 25/1.
I saw "grass clippings" at 20:1 and thought "those must be green grass clippings".
I didn't notice hay. I saw straw3 at 75:1, but straw should be the long stems, not the stems.
I usually start with much more brown than green. Then I add kitchen waste and coffee grounds in the right- center part, for as many weeks as it takes until it looks "rich", then starts to look a little gooey.
Then I mix a little of the "leaner" surroundings back into that area and set it aside (to the right) to finish.
Then I add the kitchen waster to a new "center" that's a little farther to the left.
I too have been looking for a reliable nitrogen ratio for dried grass. I found the value on the Compost Junkie sight as well, but being only one source with no references, I hold it suspect. I have adapted the compost calculator from WA State U (https://puyallup.wsu.edu/soils/compost-mix-calculator/) to match my feedstock so I can calculate my compost recipe ratios. I have a lot of dried grass as our school district gardeners bring me all their grass clippings (and dried leaves), which I dry out on a raised drying bed made from pallets and hardware cloth. Storing fresh grass clippings is messy and smelly, and I didn't want to pass on this free local feedstock. Back to the point - I'm still looking for a reliable ratio for dried grass. I'm currently using a 40:1 ratio in my calculator, which makes it a brown, but this ratio was extrapolated from other similar feedstock numbers. Our local Office of Sustainability just provided me funding to implement a worm composting system for a 1,100 student middle school, and in the grant I included funding to have my dried grass clippings analyzed by a soil lab. I'll post my lab results once I get them.
Keep on doing the rot thing.