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Title (Primary) Response of soil microbial biomass, urease and xylanase within particle size fractions to long-term soil management
Author Kandeler, E.; Stemmer, M.; Klimanek, E.-M.;
Journal Soil Biology & Biochemistry
Year 1999
Department BOFO;
Volume 31
Issue 2
Language englisch;
Abstract

We investigated whether long-term management of a Haplic Phaeocem (FAO) influences organic C, microbial biomass and enzyme activities in the bulk soil and in particle size fractions. The following treatments were used: (1) no fertilization (control), (2) NPK, (3) 20 t FYM ha(-1) (farmyard manure), (4) 20 t FYM ha(-1) + NPK, (5) 30 t FYM ha(-1) and (6) 30 t FYM ha(-1) + NPK. The fertilizers were applied to plots of a crop rotation (sugar beet, potatoes, winter wheat, spring barley, alfalfa); inorganic fertilizers were applied every year, FYM was applied every second year. Particle size fractions were obtained by low-energy sonication (0.25 kJ g(-1)) and a combination of wet sieving and centrifugation, releasing the size fractions 2000-250, 250-63, 63-2, 2-0.1 and <0.1 mu m. FYM increased microbial biomass, N-mineralization, urease, arginine deaminase and alkaline phosphatase activity of the bulk soil, whereas the effect of additional NPK fertilization depended on the enzyme assayed. Xylanase activity of the bulk soil was mainly influenced by the quality and quantity of the residues and by the amount of below-ground plant biomass. C and N contents (related to fraction dry weight) increased with diminishing particle size. The mean recoveries of C and N contents after the fractionation procedure were 96.8 and 97.1%, respectively. Organic amendments (20 vs 30 t FYM ha(-1)) induced an equal increase of organic C and total N in all particle size fractions (2000-250, 250-63, 63-2, 2-0.1 and <0.1 mu m). Unfertilized soils were characterized by a higher C-to-N ratio of the particles (2000-250 and 250-63 mu m) than the organically and inorganically fertilized soils. Microbial ninhydrin-reactive N was recovered to 73.6% after the fractionation procedure. Highest concentrations of ninhydrin-reactive N were found in the clay (2-0.1 mu m) and silt fraction (63-2 mu m), lowest in the coarse sand fraction (2000-250 mu m). The increased ninhydrin-reactive N in the bulk soil after long-term amendment with FYM is mainly attributed to an increase of ninhydrin-reactive N in the clay and silt fractions. Therefore, longterm organic amendments increased the capacity of the small-sized fractions to protect soil microorganisms. Urease activity was mainly located in the 63-2 and 2-0.1 mu m fractions, whereas the coarse and fine sand particles accumulated disproportionately higher amounts of xylanase. The predominance of xylanase and urease in different particle size fractions depends apparently not only on the location of soil microorganisms and their substrates but also on the mechanisms of enzymes to adsorb and bind onto mineral and organic particles.
ID 8084
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=8084
Kandeler, E., Stemmer, M., Klimanek, E.-M. (1999):
Response of soil microbial biomass, urease and xylanase within particle size fractions to long-term soil management
Soil Biol. Biochem. 31 (2), 261 - 273