The research was carried out for 7 years, 1998-2005, in a semi-agricultural watershed, called Centonara, set within a natural regional park and situated in the hills surrounding Bologna, northern Italy. This area is characterized by one of the most interesting badlands complexes in Europe and represents one of the main points of naturalistic interest. The watershed is partially cultivated (about 30% of the total area) with arable crops, mostly cereals and alfalfa. To evaluate the impact of agricultural activity on the eco-sustainability of this area, the nitrogen (N) balance was computed. Although it is only an estimation of the potential environmental damage, the nitrogen balance is a useful indicator of the risk posed to the environment from excessive nitrogen and can be useful to understand the possible effects of a certain type of agricultural and environmental management and policy. The balance was calculated by computing the difference between all inputs and all outputs. The nitrogen balance of the watershed was found to be sustainable, with an annual nitrogen balance ranging between -2.3 and +4.4 kg ha -1 . Despite the limited presence of arable lands, the agricultural management played the main role in determining the sustainability of the watershed, strongly influencing both the principal N sources and sinks. In fact, major N inputs derived from inorganic fertilization (8.1-15.5 kg ha -1 yr -1 ) and biological fixation (8.3-14.3 kg ha -1 yr -1 ). On the other hand, plant removal constituted the most important output (17.7-25.6 kg ha -1 yr -1 ). N losses in the drainage water were limited (3.0-9.5 kg ha -1 yr -1 ) and the Centonara stream water was found to be unpolluted, with a nitrate concentration always below the EU limit for drinking water. The similar magnitude of total N inputs and outputs indicated that the crop management, especially the crop rotation and the N fertilization, in the Centonara watershed has reached a good level of ecological sustainability. Finally, the computation of the N fertilizer-use efficiency index resulted to be useful to identify which crop and which type of management (organic or conventional) were more suitable for the pedo-climatic condition of the studied area.

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The NASA Magellan Venus Radar Mapper spacecraft was launched into an interplanetary transfer trajectory to Venus on May 4, 1989, and will be placed into orbit around Venus on August 10, 1990. The orbiter carries a 12-cm-wavelength, multimode radar system. In the synthetic aperture mode it is capable of imaging most of the Venus surface at a resolution of better than 300 m, approaching 120 m over more than half the planet. In the altimeter mode it will determine topographic relief to a vertical accuracy of better than 50 m averaged over a surface resolution cell approximately 10 km in diameter where the surface relief is not too extreme. In the radiometer mode the radar receiver can determine the surface radio emission brightness temperature with an absolute accuracy of 20 K, at a resolution of 2 K. Tracking of the orbiter' s coherent radio telemetry transmitter will permit observations of small accelerations related to gravitational inhomogeneities in the planet' s interior. Objectives of the mission include deducing the geological history of the surface and the geophysical state of the interior. Specific attention focuses on the origin, present distribution, and activity of four geological processes that modify the surface: (1) volcanic and tectonic; (2) impact; (3) erosional, depositional, and chemical; and (4) isostatic and convective. Data products resulting from the mission will be made available to members of the scientific community through NASA's Planetary Data System.

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