Simple Homemade Manure Using Grass Clippings & Cardboard

I’ve recently been writing (to RWC email list subscribers) about the value, and challenges of using grass clippings as a food material in vermicomposting systems.

In the past, I’ve always been fairly cautious about recommending its use in typical, small-scale, enclosed systems because it can be tricky to work with – even potentially hazardous for the worms, if you’re not careful. In open outdoor systems, things become a whole lot easier, but that’s another topic for another time.

In smaller-to-medium-sized, enclosed systems it is important to only add fresh clippings in moderation, since they can release ammonia gas (very dangerous for worms), cause overheating, and just generally create an environment that’s not particularly worm-friendly.

Aside from simply adding the clippings in very small amounts, another (arguably much better) option is to use the clippings to make various types of food mixes which will be much better suited for your worm bin.

Over the years, I’ve referred to these types of food mixes as “Homemade Manure” (HMM).

[NOTE: the link takes you to a search on the blog for the term “homemade manure” – you can peruse past posts by scrolling down]

Originally, I came up with the concept in an effort to offer people an easy-to-make, highly-beneficial alternative to real livestock manures. There’s no doubt that manures are excellent for vermicomposting, but they are not always easy to obtain for the average home vermicomposter, and not everyone wants to work with them.

The ‘big idea’ with the homemade variety is to mix together (and allow to decompose) the same key components you find in aged, bedded livestock manures: 1) N-rich “food” component, 2) C-rich “bedding” component, and 3) some sort of microbial component. The ratios of the food and bedding components will be dictated by your intended end use. eg. If you are trying to make a habitat material, you will want more bedding materials – if wanting a more nutritious mix, you can go a bit heavier with the food materials.

A very important point to emphasize here is that there are literally countless different ways to make a homemade manure (if you go through my blog posts on the topic, this will be readily apparent). Other than the importance of the 3 key components, the sky is the limit in terms of what materials and ratios you use.

OK, with all this preliminary chatter out of the way, it’s finally time to get to the main focus of this blog post…

Earlier this week, feeling inspired about the grass clippings topic – and thinking about various ways to put clippings to good use – I thought it might be fun to whip up a super simple batch of HMM, using grass clippings + an ample supply of cardboard and brown paper I’ve been accumulating. In the spirit of keeping things “super simple”, I decided to leave all the bedding mostly in its original form (i.e. no shredding, or even much in the way of coarse ripping).

Step #1 for me was to dampen and rinse the bedding. This helped me to hit the ground running with the breakdown process, while also potentially rinsing away chemical residues that might have been in some of the materials.

Next, I gathered and organized my supplies. NOTE: the grass clippings I used were somewhat aged already, but most of the yellow you see in the bucket is actually sunlight.

Then, it was a simple matter of adding alternating layers of bedding and clippings.

Grass clippings – especially once they’ve aged a bit – already have a decent microbial population on them, but I decided to add a handful of semi-rotten wood chips in for good measure. For more ideas about microbial inoculation, be sure to check out my “Living Materials” guide.

I continued with a couple more bedding – grass layers (to bring the level up closer to the top)…

…before watering the system lightly and putting on the lid.

I decided to keep the bin down in my basement, so as to minimize the chances of it becoming infested with various flies/gnats. This is a very important consideration any time you are making these HMM mixes outdoors. Not a big deal at all if you are using the material outside as well, but if you are using it as a food indoors, you likely won’t want to end up with these flying organisms in your bins.

After a few days of sitting, I could see that the level in the bin had gone down a fair bit.

So, I decided to top up with additional layers of cardboard and clippings.

Now, I’m just going to let everything sit and “brew” for a bit. There are no strict rules for how long the aging process should be, but 1-3 weeks will likely be the “sweet spot” in this particular case.

Stay tuned!

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    • George Scherma
    • June 1, 2024

    Some of the pictures look like dinner salads my wife makes, but other than that, it’s an excellent article. The pictures of how you layer your stuff are helpful. Good job!

    • Vinny
    • June 2, 2024

    Going to try out this.
    So much cardboard in green bin and the grass needs cutting so I ready 🙂

    • Bentley
    • June 2, 2024

    GEORGE – LOL, that’s funny. Just imagine if I had added comfrey? It would have looked positively delicious! 😉

    VINNY – Sounds great! I’ll be interested to hear how it works out for you! 😎

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