The first weeks results of our Rotbot experiment to show how the C:N ratio affects the rate of decompostition has been published on the carryoncomposting Rotbot page  Rotbots & C:N ratio

 5 bottles were used containing different ratios of Greens and Browns : 100%, 25:75%, 50:50 75:25%and 100:0%). The higher the ratio of Greens the faster the process 

The next stage is to repeat the experiement using more tightly packed material which should retain more moisture

Decomposition rates using different ratios of Green and Browns.  

 Carbon and nitrogen are the most important of the many elements required for microbial decomposition of organic matter to produce compost.  The C: N ratio (Carbon: Nitrogen Ratio) is often referred to in composting books and websites, although less emphasis is placed on calculating the precise ratio of a mix than was once the case. Home composters are now advised to use equal amount of Greens and Browns rather than a calculated mix to provide an “ideal” C:N ratio of 25-30:1.

 This project, using Rotbots, should show the temperature during composting using Greens and Browns, in different proportions and together with observation of the state of the decomposing material, will show whether the ratio of Greens (nitrogen rich) and Browns (carbon rich) will affect the microbial activity in, and the rate of decomposition of, the organic material in a Rotbot. The temperature should be recorded using a soil or compost thermometer. 

 When choosing the materials to use in this exercise it is suggested that, if this is forming part of a class experiment, Greens and Browns with a range of C:N ratios are used by each group to see if materials with different C:N ratios will react differently

Composting Spent Hops

Composting spent hops is not new but until recently they were a material available to relatively few home composters. With the increased in craft brewers this has changed. Many bag their spent hops and made available for collection free of charge to anyone prepared to collect it. An offer frequently taken up by allotment societies and gardeners.

Spent Hops can be composted or used directly as a mulch they are nitrogen-rich.  To achieve the right C:N ratio a good quantity of Browns need to be provided and if the hops are provide/composted while wet they will need sufficient carbon rich material, such as shredded paper, sawdust or woodchip, to help absorb the water and prevent anaerobic decomposition. Compost junkie recommends 1 part spent grains/hops to 3 parts carbon material. (http://www.compostjunkie.com/can-i-compost-spent-beer-grains-and-hops.html)

Warning

Hops are toxic to dogs and while hop flowers have a bitter taste spent hops are likely to taste better. Details of symptoms can be found at  (https://wagwalking.com/condition/hops-poisoning) (http://www.petpoisonhelpline.com/poison/hops/) . Becuase of their toxicity  I do not recommend using them as a mulch or on an open compost heap, or bin, in any area to which dogs have , or might have, access.

I am giving a talk on Home Composting to members of Long Eaton and District Horticultural Society (http://www.longeatonhorticulturalsociety.co.uk/)   on 17th July.  We will be looking at the composting processs, the correct mix of greens and browns, types of compost bins suitable for home composting, wormeries and liquid feeds 

We will have a composting stand at Overseal; Gala day on 14 July (http://www.oversealgala.org/ )

This will give children the chance to make a Compost bin in a bottle. I would welcome donations of 2litre plastic bottles so please bring empies to the event.

Children will take thei completed Rotbots home to watch the materials decompose and omce this process has been completed a seed can be planted in the pot. Fresh life (and food?) will rise again from the compost made by the decomposed plants.