Evaluation of Wood Ash as Additive for Cow Manure Composting

Abstract

A B S T R A C TThis study was conducted to produce high-quality compost using both cow manure and wood ash that can specifically be used to increase the fertility of soils in tropical regions. Increased proportions of wood ash were co-composted with cow manure. During composting, the composts produced presented the classical composting temperature curve and attain a thermophilic composting phase (about 60 o C). After 117 days of composting, the produced composts (CMA 0%; CMA 5%; CMA 10% and CMA15%) had a C/N ratio between 16 and 30, and their pH, was basic, indicating maturity. They were rich in minerals (Mg; Ca; K+; and Na+) and poor in heavy metals (Zn; Cu and Pb). Wood ash addition raise the fungal communities except for CMA 0% and did not impair significantly on bacteria communities; however, addition of high amounts of wood ash could reduce the metabolism of the microbial communities including cellulase activity that showed a proportional decrease according to the added amount except for CMA 15%. The composts showed a germination index greater than 80% at all concentrations, indicating the absence of phytotoxicity. Therefore, co-composting of cow manure with wood ash (<15%) allowed to obtain a good organic fertilizer with higher liming potential, nutrient content, and less hazardous material which could be used in farms to remediate acidity of tropical soils.

The Potential of Cassava (Manihot esculenta Crantz) Peels as an Organic Fertilizer

“…The salinity of a compost is measured by its electrical conductivity, which greatly depends on the nutrient content of the compost and determines the phytotoxicity of a compost. Therefore, the increase of EC regarding the amount of cassava peels, which was composted, could be explained by the process of organic matter mineralisation, which always takes place during the composting process [21] [22]. That increase might also be the result of the maturation phase, which is the last phase of the process of composting, during which there is a production of organic acids and soluble salt.…”

“…Moreover, it could also be explained by the slight amount of Mg 2+ ; Ca 2+ ; K + and Na + in the produced composts. [22] [23] [24]. As a result, a great amount of cassava peels might increase the salinity of the final product that might cause osmotic problems and affects water intake ability [22].…”

“…[22] [23] [24]. As a result, a great amount of cassava peels might increase the salinity of the final product that might cause osmotic problems and affects water intake ability [22]. However, the value of the electrical conductivity of each produced compost was below the value that might cause a toxical effect on plants (3,7 à 8,8 mS/cm) [25].…”

“…The slight increase of pH from the obtained composts (C1, C2, C3, and C4) should be explained by the presence of a thermophilic phase in which there is the degradation of organic acids, produced during the acidophilic phase, which allows a phenomenon of alkalization of the compost, which is increased by the mineralization of the soil's nitrogen [22] [26] [27] [28]. That increase in pH may be also attributed to the lack of production of some organic acids [22]. It could also be the lack of CO2 mineralization of organic material [29].…”

The impact of the addition of natural materials on the composting of animal manure

“…Addition of these materials in the process of The impact of the addition of natural materials on the composting of animal manure storage and composting of organic substrates results in better utilization of nutrients, reduction of risk of leakage of pollutants, especially nitrogen and phosphorus, into soil and water as well as reduction of contamination of individual environmental compartments by microorganisms (Sasáková, 2015). Bougnom et al (2020) reported, that the co-composting of cow manure with wood ash (<15%) allowed the authors to obtain a good organic fertilizer with higher liming potential and nutrient content.…”