ABSTRACT S t r e s z c z e n i e . Etapy mineralizacji azotu organicznego w środowisku glebowym: proteoliza, amonifikacja, nitryfikacja. Enzymy biorące udział w tych procesach. Podstawy oznaczeń aktywności enzymów w glebie. Proponowane metody dla wyznaczenia aktywności wybranych enzymów w glebie. S ł o w a k l u c z o w e : gleba, minearalizacja azotu organicznego, metody oznaczania aktyw-ności enzymów Zasadnicza część masy azotu organicznego gleby wchodzi w skład trwałej substancji organicznej gleby – próchnicy jako frakcja białek i produktów ich hydrolizy, aminokwasów związanych z polifenolami, cukrami oraz połączeń tych produktów z minerałami gleby. Składnikami gleby zawierającymi azot są również kwasy nukleinowe, nukleoproteidy i aminocukry [6]. Związki organiczne azotu połączeń próchnicznych i dostających się do gleby w postaci resztek zwierzęcych i roślinnych substancji zawierających azot organiczny, ulegają złożonym przemianom biochemicznym. W tym procesie tworzą się dostępne dla roślin związki azotu mineralnego. We wszystkich sta-diach poszczególnych etapów ich przemian (proteolizy, amonifikacji, nitryfikacji, denitryfikacji) mają udział mikroorganizmy wytwarzające specyficzne enzymy wewnątrz żywych komórek lub enzymy pozakomórkowe wydzielane do środo-wiska, nagromadzone w glebie, osadzone na koloidach organicznych i mine-ralnych [27,28,41]. * Pracę wykonano w ramach projektu badawczego nr 3P04G 04324 finansowanego przez KBN w latach 2003-2005.

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    ABSTRACT: A simple, rapid and inexpensive method to determine microbial activity potentials, based on ammonification of arginine, was developed and tested on bacterial cultures and soil samples. The results are highly reproducible and correlate well with respiratory activities. Ammonification starts immediately after the addition of arginine and is linear for more than l h. Both properties show that physiological status and number of microorganisms remain stable during the assay.
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    ABSTRACT:  Oregon soils from various management and genetic histories were used in a greenhouse study to determine the relationships between soil chemical and biological parameters and the uptake of soil mineralized nitrogen (N) by ryegrass (Lolium perenne L.). The soils were tested for asparaginase, amidase, urease, β-glucosidase, and dipeptidase activities and fluorescein diacetate hydrolysis. Microbial biomass carbon (C) and N as well as metabolic diversity using Biolog GN plates were measured, as were total soil N and C, pH, and absorbance of soil extracts at 270 nm and 210 nm. Potentially mineralizable N (N0) and the mineralization rate constant (k) were calculated using a first order nonlinear regression model and these coefficients were used to calculate the initial potential rate of N mineralization (N0 k). Except for Biolog GN plates, the other parameters were highly correlated to mineralized N uptake and each other. A model using total soil N and β-glucosidase as parameters provided the best predictor of mineralized N uptake by ryegrass (R 2 =0.83). Chemical and biological parameters of soils with the same history of formation but under different management systems differed significantly from each other in most cases. The calculated values of the initial potential rate of mineralization in some cases revealed management differences within the same soil types. The results showed that management of soils is readily reflected in certain soil chemical and biological indicators and that some biological tests may be useful in predicting N mineralization in soils.
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