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Expressions for the expected value of the first mode damping ratio are derived from 122 seismic responses from concrete buildings and 81 from steel. The results include dissipation at the soil-structure interface and are appropriate for the situations where this source of dissipation is not included in the model.Comparisons between models of different complexity indicate the appropriateness of using a single regressor, which is taken as the building height. It is shown that the Fisher Information on the damping increases with the number of response cycles and this result is used to define weights for the residuals of the regression.The effective damping in steel buildings, with the exception of very tall structures, is found larger than the 2% typically used in practice, while the 5% assigned to concrete proves to be close to the mean of the data set.

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A 2-year field experiment was conducted on maize (Zea mays L.) to explore effective ways to decrease soil CO2 emissions and increase grain yield. Treatments established were: (1) no mulching with urea, (2) no mulching with controlled release fertiliser (CRF), (3) transparent plastic-film mulching (PMt) with urea, (4) PMt with CRF, (5) black plastic-film mulching (PMb) with urea, and (6) PMb with CRF. During the early growth stages, soil CO2 emissions were noted as PMt > PMb > no mulching, and this order was reversed in the late growth stages. This trend was the result of topsoil temperature dynamics. There were no significant correlations noted between soil CO2 emissions and soil temperature and moisture. Cumulative soil CO2 emissions were higher for the PMt than for the PMb, and grain yield was higher for the PMb treatments than for the PMt or no mulching treatments. The CRF produced higher grain yield and inhibited soil CO2 emissions. Soil CO2 emissions per unit grain yield were lower for the BC treatment than for the other treatments. In conclusion, the use of black plastic-film mulching and controlled release fertiliser not only increased maize yield, but also reduced soil CO2 emissions.

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