Author(s): Mata, Ricardo Manuel Reis
Date: 2016
Persistent ID: http://hdl.handle.net/10400.5/12979
Origin: Repositório da UTL
Subject(s): yeast; soil; groundwater; pollution; greenhouse gases
Author(s): Mata, Ricardo Manuel Reis
Date: 2016
Persistent ID: http://hdl.handle.net/10400.5/12979
Origin: Repositório da UTL
Subject(s): yeast; soil; groundwater; pollution; greenhouse gases
Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia - UL
The yeast production industry (e.g. distillery, brewing, baking industries) has been growing globally over the last years generating a large amount of sub-products. Laboratory experiments, under controlled conditions, were performed to investigate the impact of yeast waste application to a sandy texture soil. Experimental treatments were: surface application of yeast and decanted-yeast (CMSs and CMSds), surface application of yeast and decantedyeast followed by incorporation in the 0-5 cm soil layer (CMSm and CMSdm), surface application of ammonium nitrate (AN) (not applied in short-term experiment) and a control (soil only) (CTR). The amount of yeast applied was 2 g in the short-term experiment and equivalent to 170 kgN.ha-1 in the long-term experiment. A short-term (38-day period) leaching experiment was performed with 5 weekly irrigation events (5 treatments × 3 replications) to assess N, P, K losses. Results showed that yeast application increased NH4+, PT and KT leaching relative to control while decreased NO3- leaching relative to a high initial content of control, during first irrigation events. Incorporation treatments increased NH4+, NO3- and PT losses earlier. KT losses were higher in surface treatments. A long-term leaching experiment (73-day period) with 6 irrigation events every two weeks was then performed (6 treatments × 4 replicates) to assess N, P losses. A two parallel incubation experiment (6 treatments × 3 replicates) were simultaneously performed to measure GHG emissions (CO2, N2O, CH4) and to assess the N mineralization in each treatment. Results showed that yeast application increased initial NH4+ concentration in leachates and soil relative to control and NO3- increased afterwards. N2O and CO2 increased significantly relative to control on the first days after yeast application. AN treatment emissions were very similar to control but had a small increase of N2O. CH4 emissions were insignificant. The global warming potential (GWP) of yeast and AN were 6× and 2× times higher than control, respectively