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- Effect of Biochar on Emission of Greenhouse Gases and Productivity of Cardoon Crop (Cynara cardunculus L.)Publication . Barracosa, Paulo; Cardoso, Isabel; Marques, Francisco; Pinto, António; Oliveira, Jorge; Trindade, Henrique; Rodrigues, P.; Pereira, José L.S.Cardoon could be cropped for agro-environmental, industrial, and pharmaceutical purposes. The aim of this study was to assess the effects of biochar on emissions of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4), and productivity of cardoon crop. A pot experiment was run outdoors from April to August 2018, with a cardoon plant per pot. The following four treatments, with four replicates each, were applied: control, soil only; mineral, soil amended with mineral fertilizer (2.5 g N m−2); biochar, soil amended with biochar (1 kg m−2); and mineral+biochar, soil amended with mineral fertilizer (2.5 g N m−2) and biochar (1 kg m−2). The morphological characteristics and biomass production of cardoon plants were evaluated, and the fluxes of N2O, CO2 and CH4 were measured by using the closed chamber technique. The application of biochar combined with mineral reduced N2O emissions by 36% and global warming potential (GWP) by 26% relative to mineral. However, the cumulative CO2 and CH4 emissions as well as yield-scaled GWP were not significantly different among amended soil treatments. Furthermore, the biomass production was increased by 50% by the application of biochar combined with mineral fertilizer relative to mineral. It was concluded that biochar combined with mineral fertilizer is recommended as a pathway mitigation for agro-environmental purposes, because it reduces the global warming potential and could increase the biomass production of cardoon plants.
- A 3-year field study to assess winter cover crops as nitrogen sources for an organic maize crop in Mediterranean PortugalPublication . Perdigão, Adelaide; Pereira, José L.S.; Moreira, Nuno; Trindade, Henrique; Coutinho, JoãoCurrent environmental concerns, the rising economic and environmental costs of mineral fertilizers and the need to respond to the limitations of N fertilization in organic farming motivate the search for alternative sources of N in maize cropping. Forage legumes used as winter cover crops may improve soil N fertility and offer benefits to the environment. The aim of this study was to examine the effects, in a factorial field experiment, of two sowing dates (SD) and nine different cover crop treatments (balansa clover, crimson clover, gland clover, arrowleaf clover, French serradella, yellow lupin, Italian ryegrass, a cover mixture and a weedy fallow) as a potential alternative N source in an organically managed maize crop. The experiment was conducted at Viseu (Portugal) for three years (2007/2008, 2008/2009 and 2011/12), in the same field. Results showed that maize grain yield was not influenced by cover crop species but was affected by SD and the higher dry matter (DM) aboveground biomass production was observed in early SD (6.1 t ha 1). The cover crops revealed their importance in maize N uptake: yellow lupin of earlier SD had the highest N uptake (83.6 kg N ha 1), but this was not significantly different from balansa clover (83.2 kg N ha 1). Ryegrass was the most efficient in depleting soil mineral N but values were just significantly lower than yellow lupin. Lupin was the least efficient, leaving more mineral N in the soil than the others cover crops, immediately before the period when the risk of leaching is high. It was concluded that, under the edaphoclimatic conditions tested, most of the tested cover crops were efficient in supplying N to maize, and balansa clover had the best performance.
- Influence of Nitrogen Application and Drip Irrigation on Greenhouse Gas Emissions and Yield of Cardoon Crop (Cynara cardunculus L.)Publication . Barracosa, Paulo; Antunes, Manuela; Marques, Francisco; Pinto, António; Oliveira, Jorge; Trindade, Henrique; Pereira, José L.S.Background: Cardoon is a multi-purpose crop with a wide spectrum of potential applications. Objective: The aim of this study was to assess the effects of nitrogen (N) application and drip irrigation practices on emissions of nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) and morphological characterization and biomass production of cardoon crop. Methods: The experiment was run under field conditions from April to August 2018. The field experiment was a randomized complete block design with three replications and four treatments: (i) non-amended soil as control (CONTR); (ii) mineral N fertilizer and non-irrigated (NITRO); (iii) non-fertilized and drip irrigation (IRRIG); and (iv) mineral N fertilizer and drip irrigation by fertigation (FERTI). The fluxes of N2O, CO2 and CH4 were measured by the closed chamber technique and the morphological characteristics and yield of cardoon plants were evaluated per treatment. Results: Results showed that the N2O emissions and global warming potential were not significantly different among the application of mineral N fertilizer itself or by drip fertigation with an emission rate of 0.5% of N applied and -6,8 t CO2-eq. ha-1. The characteristics related to biomass production did not differ significantly (p>0.05) between amended treatments although numerically higher in IRRIG treatment. Conclusion: It was concluded that the application of mineral N fertilizer itself or drip fertigation had no significant effect on N2O emissions and global warming potential. Additionally, the plant growth, including biomass production, increased due to drip irrigation, but not significantly.