No abstract

Chemical stability is one of the key quality control criterion for complex degradable materials with an active microbial community like compost tea, but largely understudied. A laboratory study was performed to assess the chemical stability of varying concentrations (0, 2.5, 5, 10, 15, 20, 30, 50 and 100%) of municipal solid waste (MSW) compost tea stored at different temperatures (4°, 10°, 22° and 35°C) and storage time (0, 13, 26 39 and 52 days). A 2-dimension principal component biplot confirmed close relationship amongst total dissolved solids (TDS), electric conductivity (EC) and salinity while pH was less related and turbidity was isolated. TDS in the MSW compost tea did not change at a storage temperature of 4oC or 10oC but was significantly (P<0.05) increased by 4.3% when the storage temperature was raised to 35oC. Also, TDS increased sharply from 93.25 mg/L on day 1 to 111.31 mg/L on day 26 after which it remained unchanged. EC increased by approximately 8% only when the MSW compost tea was stored at 35oC. The EC on the other hand increased by 19.4% from 131.28 µS/cm on day 1 when it peaked on day 26 and plateaued off to day 52. The change in pH was small and ranged from 7.44 to 7.67. Concentration had the strongest association with TDS, EC, salinity and turbidity and did not vary with storage time nor temperature. A multilinear regression (Y = αD + βC + γT + k) showed significant (P<0.05) coefficients for all the independent variables except the coefficients for temperature in the turbidity, salinity and pH regression models. In conclusion, the chemical stability of the MSW compost tea was dependent on the storage temperature and storage duration. Chemical stability was reached after 26 days of storage while cold storage at 4oC or 10oC reduced chemical alteration.

Cut flower vase life can be extended by various natural products, but their efficacy when mixed with compost tea is not reported. A study was performed to determine cut carnation (Dianthus caryophyllus cv. White Sim) vase life in 1 L of formulations (1) C3.5: 3.5% compost tea + 15 mg putrescine; (2) R5L10: C3.5 + 5 mL rosemary (Salvia rosmarinus) + 10 mL lemon (Citrus limon) extracts; (3) R10L10: C3.5 + 10 mL rosemary + 10 mL lemon extracts; (4) R5L20: C3.5 + 5 mL rosemary + 20 mL lemon extracts; (5) R10L20: C3.5 + 10 mL rosemary + 20 mL lemon extracts; (6) Chrysal: Floral Chrysal Clear (positive control); and (7) Dw: distilled water alone (negative control). The 15 mg putrescine significantly (P=0.002) reduced compost tea turbidity by 34%. The neutral pH of C3.5 and Dw did not change. However, pH increased by 24% in Chrysal and reduced by 39% in R5L10, R10L10 and R5L20 and by 54% in R10L20 on day 11. TDS and EC were highest in Chrysal from days 1 to 11. Petal discoloration, wilt, shrinkage and neck bend were delayed by C3.5 followed by Chrysal and then R5L10, but were accelerated by the other treatments. In conclusion, the cut carnation cv. White Sim longevity as influenced by variations in the vase solutions was Chrysal (14 days) > C3.5 (12.6 days) > R5L10 (10.7 days) but ≤ 9 days in the other treatments. These results were confirmed by a 2-D principal component analysis biplot. Future study will investigate microbial interaction.