Composting Coffee Waste

Fresh pulp ready to be composted

Fresh pulp ready to be composted

This morning a friend asked if he could use coffee grounds in his compost pile? My immediate response was “yes, of course.” My horticultural training has taught me that any composted plant product would only add organic matter to your soil, enriching the soil. But, this piqued my curiosity in learning more about the use of coffee grounds in composting and so I researched this a bit more.

In 1995, Washington State University (WSU) Extension was asked this question by local coffee houses, to which they could not find an answer. So, the WSU Master Gardeners performed experiments. Their findings indicated that coffee grounds composted in worm bins provided excellent compost with a carbon-to-nitrogen ratio of about 20:1, almost similar to that of grass clippings, which is about 2% nitrogen. Other chemistry experiments on coffee grounds show that even though roasted coffee is fairly acidic, most of the acidity is lost in the brewing process, leaving the spent grounds mostly neutral with a pH of about 6.9.

Vermicomposted pulp

Vermicomposted pulp

In areas of coffee cultivation, the coffee pulp waste can also be composted and reused as organic matter in the farms, improving the soil organic matter content. When I was in Jamaica in January, I had to opportunity to visit the Clifton Mount Estate. I got a personal tour of the plantation by its owner, Mr. Richard Sharp, who maintains the farm impeccably. After touring his processing facility, he showed me his composting area, where the pulp waste is composted using vermiculture or vermicomposting. The resultant organic matter is used in the farms as organic fertilizer. The Clifton Mount estate produces above average coffee yields, one of the reasons for which is possibly the use of this rich organic matter.

Considering the high nitrogen content of spent coffee grounds, I hope as you brew and drink you morning coffee, you will consider putting these grounds to good use by recycling them back to mother earth, helping sustain more plant growth!

 

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Posted in Coffee culture, Farms, Production/Agronomy, Sustainability