Following on from yesterday's post about Soil Organic Carbon (SOC) in Indonesia, compiled by Indri from the Think team. This time, we are talking about SOCs that are more than just agricultural, such as biogas and bio-slurry, which is the organic fertiliser we are working with.
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Supplementing carbon to soils, such as compost, manure, digestor from anaerobic digestion (AD) of organic matter (e.g., manure), harvesting residues, or processed organic fertiliser can be performed to improve organic matter levels in agricultural soils. AD-based bioenergy can provide massive potential in putting CO2 emissions into negative territory by converting biomass into bioenergy (biogas), then sequestering the carbon produced into the soils in the forms of organic fertilisers.
Considering the high livestock population in Indonesia (Table 7), which has steadily increased in the last three years, there is a massive potential in biogas and organic fertiliser (bioslurry). Bioslurry is a co-product of anaerobic digestion of wet organic waste) production from animal manure via anaerobic digestion processes. Organic matter content in bioslurry can reach up to 27%-weight, 29% and 26% for cow dung, poultry manure and buffalo dung, respectively (Islam, 2011). A study has estimated the total biogas production from manure in Indonesia to be of 9,595.6 Mm3/year or (Khalil et al., 2019), and given that bioslurry is produced three times more than biogas of total dry matter of manure, bioslurry has become a promising carbon sequestration agent through SCE.
Volume-wise, animal manure is also the single largest potential resource of soil organic matter and other macro-and micronutrients to supplement soils. To date, most animal manure is put on soils without any manure processing. However, upgrading animal manure to a high-quality organic fertiliser through anaerobic digestion could better the outcomes by producing energy in the forms of biogas. This activity can reduce carbon emissions from fossil gas or firewood, reduce volumes (hence reducing storage problems), exterminate pathogens, and enhance soil nutrients. On top of that, as an add-on, climate change mitigation technology, animal manure's further treatments could also significantly reduce CH4 emissions (Ministry of Agriculture, 2020).