HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. Abstract -The efficiency of a rye cover crop as a preventive measure for nitrate contamination in water resources was assessed in field tests. The study region (Galicia, NW Spain), which is severely affected by this environmental impact, has an annual average precipitation markedly exceeding the evapotranspiration level. Two additional corrective measures (viz. buried wheat and lupin green manure) were also studied in parallel. A randomized complete block experimental model spanning a period of three years was used to systematically determine the organic matter, total N, NO 3 --N and NH 4 + -N contents, and the C/N ratio, in the 0-20 and 20-40 cm soil layers. Based on the significance of the different effects examined in the variance explanation model (viz. the repeated measurements general linear model) as evaluated using multivariate comparisons, the rye treatment proved more efficient than the other two corrective practices at controlling NO 3 -leaching from soil. By contrast, the application of the two plant residues to the soil exposed a priming effect induced by the simultaneous incorporation of mineral N. The suppression of the individual effects of some variability sources revealed a clear fertilizing effect in the green manure and net immobilization resulting from the incorporation of straw into the soil.contamination / nitrate / cover crops / green manure / straw / rye / lupin

A Palexerult soil from the Pliocene raña formations in northern Spain was used to conduct acidity correction tests with limestone, gypsum rock and sugar foam waste under laboratory conditions. The soil was reconstructed in methacrylate columns that were studied over a fivemonth period. The pH and exchangeable bases in the leachates, obtained by applying an amount of water equivalent to the mean rainfall of the area from which the soil was collected, were measured under laboratory conditions along a five-month period. At the end of these tests, three

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A Typic Palexerult from northern Spain was subjected to acidity correction field tests over a period of 2 years. The experimental crop was a local rye variety and the amendments included gypsum, dolomite, limestone, and sugar foam waste, all at a 6000 kg ha -1 rate as calcium carbonate (CaCO 3 ). General analyses were integrated with specific tests for soluble and easily exchangeable aluminum (Al) forms (Al-CaCl 2 ) in addition to potassium chloride (KCl)-, barium chloride (BaCl 2 )-, and copper chloride (CuCl 2 )-extracted Al and adsorbed and amorphous Al. Two types of multiple linear regression models for production each year were established; some encompassed all studied variables and others the six Al forms only. As shown here, Al-KCl, Al-CaCl 2 , base saturation, and exchangeable Ca were the individual variables most strongly correlated with production, with R 2 = 0.865, within the topmost 12 cm. A principal component analysis exposed a substantial share of pH-dependent charge in organic matter on the cation exchange capacity of the soil.

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