The Search for the Vermicompost Substrates
Vermicomposting is a sustainable biotechnological process of producing a vermicompost in which certain species of earthworms are used to enhance the process of converting waste into an environment-friendly fertilizer.
In the process of composting, organic wastes like leguminous leaves, animal manure, rice straw, grasses, and kitchen wastes, collectively known as the substrates, are recycled into stabilized products that can be applied to the soil as organic fertilizer. The materials will undergo decomposition with the help of a worm called the African Night Crawler (ANC), which then convert the substrates into a vermicast or vermicompost.
Having the optimal composition of substrate enables efficient vermicomposting. Hence, one of CBE’s initial experiments on sustainable practices focuses on determining the right substrates to be used in vermicomposting.
The experiment on vermicomposting was conducted from November 12, 2014 to January 21, 2015. Five treatments with varying amounts of substrate were prepared for the experiment to determine the optimal combination of substrates in vermin-composting. Organic inputs like kakawate, ipil-ipil, cow manure, banana trunk were collected and shred. Shredded materials were then place in the pre-decomposition area to undergo pre-decomposition process. Raw materials were watered thrice a week to shorten the pre- decomposition process, taking it 15 days for all the raw materials to be pre-decomposed. Pre-decomposed materials were placed in the vermin-pen.
ANC which acts as decomposer were introduced to the different treatments at 2 kilos each. The vermin-pen was then covered with scaffolding which serve as barrier against bird and other earthworm predator like rat. Sufficient moisture, temperature and aeration throughout composting process were maintained. Casting of worm and compost were harvested when it reached to its harvesting period. Earthworm was used for another round of vermicomposting.
End product for treatment 3 and 4 were dark brown in colour, no foul odour and moisture content was right which is unlike the product of treatment 1 & 2. Treatments 1 & 2 were slightly wet which might create bad bacteria/microorganism, thereby stunting growth of plants and worsen nutritive properties of soil.
In treatment 1, 66% of the substrates was converted into organic fertilizer. No harvest in treatment 5 because the ANC was not able to digest the substrates because pre-decomposed materials were too wet. Treatments that contains banana trunk (1, 2) have longer period of decomposition because the substrates were slightly wet, the main cause why worms were having difficulty in digesting the food. Banana trunk was made up of 98% water which is the reason why raw materials remain wet all the time. Among the treatments, the fourth one has the highest increase in ANC within the period of one month and 17 days.
The result of the experiment is not yet definitive as more trials should be conducted. Nevertheless, there are takeaways from the experiments. First, materials with high moisture content do not make a good substrate for vermicomposting. Second, treatment with the highest amount of manure yielded the highest amount of harvest per day. The same treatment also yielded the highest increase in the ANC within the shortest period of decomposition. Below is the summary of total NPK, harvest, period of decomposition, and ANC growth for each treatment.
| Treatment | Total NPK | Harvests | Period of Decomposition | ANC growth
| :——-: | :——-: | :——-: | :——-: | :——-: |
| 1 | 4.266 | 66% | 2 months & 9 days | 50% increase |
| 2 | 2.548 | 57% | 2 months & 9 days | 0 |
| 3 | 2.37 | 49% | 1 month & 18 days | 40% increase |
| 4 | 2.94 | 53% | 1 month & 17 days | 60% increase |
| 5* | 3.44 | 0% | null | 0% |
*ANC were not able to decompose the substrates