AN EVALUATION OF FACTORS AFFECTING THE CO2- C SINK STRENGTH OF AG-LIME ADDED TO TWO TRINIDAD ACID SOILS

The most recent Intergovernmental Panel on Climate Change (IPCC) greenhouse gas (GHG) inventory guidelines recognizes that CO2 is not always the end product of ag-lime dissolution in soils and now allows countries to report on their own emission factors once it is supported by sound research findings. This study was therefore established to assess the effects of additions of organic amendments (biochar and poultry litter) and ammonium N on the magnitude of the CO2 flux and the carbon sequestration potential of ag-lime when added to two diverse soils (a peaty clay and a sand). The soil treatments with the equivalent of 80g oven dry soil (ODS) were incubated in modified 500 mL mason jars. At each measurement, the alkali-trap attached to the cover was installed ensuring proper sealing of the jar opening and left for 24 hrs to absorb the CO2 emitted from the soil. Fluxes were measured at days 1, 3, 6, 9, 10, 15, 18, 21, 24, 28 and, 31, and all soil treatments were initially brought to 100% field capacity and rewetted three times thereafter. Analysis of the data showed that soil type, organic matter and ag-lime additions had a significant effect (P<0.05) on CO2 emissions. The effect of time was significant on the rates of CO2 emissions, showing a decline in the emission rate from an overall mean of 33.8 mg CO2/kgODS/hr at day 1 down to 1.98 mg CO2/kgODS/hr. The peaty clay fluxes were consistently higher than those from the sand, and soils treated with poultry litter were also statistically (P