The effect of long-term fertilization on the content of mineralizable nitrogen in soil

abonos nitrogenados abonos npk analyse de sol application rates azote disponibilidad de nutrientes dose d'application engrais npk farmyard manure fertilidad del suelo fumier immobilisation immobilization mineralisation mineralization nitrogen nitrogen content nitrogen fertilizers npk fertilizers nutrient availability soil fertility soil testing solanum tuberosum teneur en azote trial methods trifolium repens triticum aestivum