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Food production in sustainable agricultural systems is one of the main challenges of modern agriculture. Vegetable intercropping may be a strategy to mitigate greenhouse gas (GHG) emissions, replacing monoculture systems. The objective is to identify the main emissions sources and to estimate GHG emissions of intercropping and monoculture production of collard greens, New Zealand spinach and chicory. Four scenarios were evaluated: ICS – intercropping collard greens and spinach; MCS – monoculture collard greens and spinach; ICC – intercropping collard greens and chicory; MCC - monoculture collard greens and chicory. The boundaries’ reach from “cradle-to-gate” and the calculation of GHG emissions were performed using IPCC methodology and specific factors (Tier 2). The total GHG emitted was standardized as CO2 equivalent (CO2eq). The GHG emissions in ICS and ICC scenarios were approximately 31% lower than in MCS and MCC scenarios. Carbon footprint in ICS (0.030 kg CO2eq kg-1 vegetables year-1) and ICC (0.033 kg CO2eq kg-1 vegetables year-1) scenarios were also lower than in MCS (0.082 kg CO2eq kg-1 vegetables year-1) and MCC (0.071 kg CO2eq kg-1 vegetables year-1) scenarios. Fertilizers, fuel (diesel) and irrigation were the main contributing sources for total GHG emitted and carbon footprint in all evaluated scenarios. The results suggest that intercropping systems may reduce GHG emissions associated with the production of vegetables evaluated as compared with monoculture.

O solo é um dos principais compartimentos de carbono no ecossistema terrestre, capaz de armazenar quantidades expressivas desse elemento e, portanto, a compreensão dos fatores que contribuem para as perdas de CO2 em solos agrícolas é fundamental para determinar estratégias de redução das emissões desse gás e ajudar a mitigar o efeito estufa. O objetivo deste estudo foi investigar o efeito do preparo do solo e da deposição de resíduos da cultura da cana-de-açúcar na emissão de CO2, temperatura e umidade do solo, durante a reforma do canavial, ao longo de um período de 15 dias. Os manejos avaliados foram: sem preparo do solo e mantendo os resíduos da colheita sobre a superfície do solo (SPCR); sem preparo do solo e sem resíduo (SPSR) e com preparo do solo e sem resíduo (CPSR). A menor média de emissão de CO2 do solo (FCO2) foi observada no manejo SPCR (2,16 µmol m-2 s-1), quando comparado aos manejos SPSR (2,90 µmol m-2 s-1) e CPSR (3,22 µmol m-2 s-1), indicando que as maiores umidades e menores variações da temperatura do solo, observadas em SPCR, foram os fatores responsáveis por tal diminuição. Durante o período de estudo, a menor média diária da FCO2 foi registrada em SPCR (1,28 µmol m-2 s-1) e a maior em CPSR (6,08 µmol m-2 s-1), após a ocorrência de chuvas. A menor perda de C-CO2 do solo foi observada no manejo SPCR (367 kg ha-1 de C-CO2), diferindo significativamente (p

To study Assessing the impact of tillage practices on soil carbon losses dependents it is necessary to describe the temporal variability of soil CO2 emission after tillage. It has been argued that large amounts of CO2 emitted after tillage may serve as an indicator for longer-term changes in soil carbon stocks. Here we present a two-step function model based on soil temperature and soil moisture including an exponential decay in time component that is efficient in fitting intermediate-term emission after disk plow followed by a leveling harrow (conventional), and chisel plow coupled with a roller for clod breaking (reduced) tillage. Emission after reduced tillage was described using a non-linear estimator with determination coefficient (R²) as high as 0.98. Results indicate that when emission after tillage is addressed it is important to consider an exponential decay in time in order to predict the impact of tillage in short-term emissions. A quantificação do impacto das práticas de preparo sobre as perdas de carbono do solo é dependente da habilidade de se descrever a variabilidade temporal da emissão de CO2 do solo após preparo. Tem sido sugerido que as grandes quantidades de CO2 emitido após o preparo do solo podem servir como um indicador das modificações nos estoques de carbono do solo em longo termo. Neste trabalho é apresentado um modelo de duas partes baseado na temperatura e na umidade do solo e que inclui um termo exponencial decrescente do tempo que é eficiente no ajuste das emissões intermediárias após preparo: arado de disco seguido de uma passagem com a grade niveladora (convencional) e escarificador de arrasto seguido da passagem com rolo destorroador (reduzido). As emissões após o preparo do solo são descritas utilizando-se estimativa não linear com um coeficiente de determinação (R²) tão alto quanto 0.98 após preparo reduzido. Os resultados indicam que nas previsões da emissão de CO2 após o preparo do solo é importante considerar um termo exponencial decrescente no tempo após preparo.

Made available in DSpace on 2022-04-28T22:37:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-01-01 The irrigation application is one of the most useful techniques in tropical environments, especially during dry seasons. In this study, CO2 efflux, temperature and soil moisture were studied in a field sampled with a grid having 48 points distributed in 35 × 25 m, under irrigation promoted by a sprinkler located at the center of the area, provoking different levels of water deposition, with maximum irrigation levels of 44.4 and 62.2 mm in points closer to the sprinkler. The results show that the emissions, temperature and moisture were strongly affected by the two irrigations events, having a total water level added of 106,6 mm for the points next to the sprinkler and zero for the most distant points from it. The maps of space variation of the variables, as well as the linear correlation between them, indicate that the emissions were positively related to the soil moisture and negative correlated to the soil temperature only after the irrigations events. The special variability models of soil CO2 emission changed from exponential to spherical after the irrigations events. Such results indicate that soil moisture is among possible controlling factors of the soil CO2 emission, because even with reductions in soil temperature provoked by the wetness, emissions increased strongly. Agronomia UNESP, Jaboticabal - SP Dept. de Engenharia Rural UNESP, Jaboticabal - SP Dept. de Ciências Exatas UNESP, Jaboticabal - SP Agronomia UNESP, Jaboticabal - SP Dept. de Engenharia Rural UNESP, Jaboticabal - SP Dept. de Ciências Exatas UNESP, Jaboticabal - SP