A simple method for evaluating the maturity of animal manure compost based on carbon dioxide emission rate
2005
Kumagai, C.(Miyagi-ken. Furukawa Agricultural Experiment Station (Japan)) | Saito, K. | Hatanaka, A. | Taki, N. | Saigusa, M.
A simple method based on C02 emission rate from compost was developed to evaluate the maturity of animal manure composts. Composts with different maturity made from various kinds of animal manure (cattle, swine and/or poultry) were collected from 18 composting plants in Miyagi Prefecture, Japan. The C02 emission rate of the composts was correlated to BOD (r = 0.829) and to the germination ratio of Komatsuna (Brassica rapa L.) (r = - 0.832), which are indexes of compost maturity. The results demonstrate that CO, emission rates can be used for evaluating the compost maturity. From the regression line between the C02 emission rate and germination ratio, a germination ratio of higher than 80%, which is the criterion for good quality composts, corresponds to a CO, emission rate of lower than 0.8 mg g(-1) DM h(-1). We developed an easy method to estimate the C02 emission rate. The composts' water content was adjusted appropriately, and acclimatized for 1 day. Ten grams of acclimatized compost was placed in a 100 mL bottle. Filter paper (4 cm2) impregnated with 0.05 M NaOH solution containing 200 mg L(-1) phenolphthalein was stuck to the inside of the bottle. The bottle was incubated at 35 deg C until the pink of the paper changed to white owing to CO, absorption. The time taken for the color change increased with decreasing C02 emission rate, and the C02 emission rate of 0.8 mg g(-1) DM h(-1) corresponded to 40 min for the color change. We also confirmed the validity of the 40-min criterion with the seedling experiment cultivating Komatsuna in a Noubauer's pot.
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