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A b s t r a c tThe REFLEX 2012 campaign was initiated as part of a training course on the organization of an airborne campaign to support advancement of the understanding of land-atmosphere interaction processes. This article describes the campaign, its objectives and observations, remote as well as in situ. The observations took place at the experimental Las Tiesas farm in an agricultural area in the south of Spain. During the period of ten days, measurements were made to capture the main processes controlling the local and regional land-atmosphere exchanges. Apart from multi-temporal, multi-directional and multi-spatial space-borne and airborne observations, measurements of the local meteorology, energy fluxes, soil temperature profiles, soil moisture profiles, surface temperature, canopy structure as well as leaf-level measurements were carried out. Additional thermo-dynamical monitoring took place at selected sites. REFLEX 2012 CAMPAIGN 1467After presenting the different types of measurements, some examples are given to illustrate the potential of the observations made.

Nitrogen fertilization has a significant environmental impact in Europe due to the problems of wide-spread pollution. This paper deals with a series of field experiments conducted in a semiarid region of Southeast Spain. Irrigated maize was grown under different N fertilizer rates: control as in no nitrogen applied (C; 0 kg N ha -1 ); conventional amount of nitrogen (Nc; 300 kg N ha -1 ); and theoretical optimum (No; 130 kg N ha -1 ) in a randomised block design with three replications.In 1999 and 2000, when 175 and 150 kg N ha -1 were respectively applied to No treatment, no significant differences were found. With the Nc treatment, a grain yield of 17.6 Mg ha -1 was obtained in 2001, being significantly higher than the yield obtained with the No treatment (15.8 Mg ha -1 ). This means that No rate was under the technical optimum, but both treatments were higher than C treatment (7.2 Mg ha -1 ). A fertilizer rate of 130 kg N ha -1 was lower than necessary to obtain maximum yields, although the rate of 150 kg N ha -1 did not show significant differences with regard to Nc treatment (300 kg ha -1 ) (2000).Studies about crop response to different N rates could be very useful for farmers. Regional Technology Transfer Centres are incorporating the results of these studies in a Decision Support System (DSS).

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Rising energy costs, declining groundwater supplies, increasing competition for water resources between agricultural, industrial and domestic users and irrigation-induced water quality problems are providing considerable impetus to improving efficiency in irrigated agriculture. Much of the groundwater used for irrigation is found in closed underground basins. Water percolation is the only source of water available for recharge. In some basins, the pumping rate is much greater than the recharge from percolation and ‘water mining’ occurs. The aim of this study was to compare the yield components and quality factors of sweet corn grown under different irrigation scheduling strategies. The treatment with 426 mm of seasonal irrigation offered the largest commercial yields, with an appropriate quality production, good irrigation efficiency, the highest gross margin and the best break-even point irrigation strategy. Treatments with higher application produced lower irrigation efficiencies.