Green manure legumes affect seasonal soil and leaf CO2 exchange rates in an olive rainfed orchard

Management methods that decrease requirement for agricultural chemicals are needed to reduce adverse environmental impacts. Moreover, they can play an important role in atmospheric C02 emission and fixation. We propose green manure legumes to reduce erosion, soil compaction and nitrate pollution, to improve biodiversity, soil carbon sink and fertility, to save fossil fuels and to increase yield and the nutritional value of food products. The research was carried out near Mirandela, Northeast Portugal, on a 15- year commercial olive orchard (Olea europaea L. cv. Cobrançosa), grown under rainfed conditions