Relations between enzymatic activity of soil and yields of spring barley in a long-term field experiment

abonos nitrogenados acid phosphatase alkaline phosphatase application rates barley cebada crop yield cultivos de primavera culture de printemps dose d'application engrais organique farmyard manure field experimentation fosfatasa alcalina fumier hordeum vulgare nitrogen fertilizers organic fertilizers orge oxidoreductases oxidorreductasas phosphatase acide phosphatase alcaline rendement des cultures rendimiento de cultivos rotation culturale rotational cropping spring crops ureasa urease