Showing papers by "Ellen Kandeler published in 1994"

Microbial biomass, N mineralization, and the activities of various enzymes in relation to nitrate leaching and root distribution in a slurry-amended grassland

Abstract: High rates of cattle slurry application induce NO inf3 sup- leaching from grassland soils. Therefore, field and lysimeter trials were conducted at Gumpenstein (Austria) to determine the residual effect of various rates of cattle slurry on microbial biomass, N mineralization, activities of soil enzymes, root densities, and N leaching in a grassland soil profile (Orthic Luvisol, sandy silt, pH 6.6). The cattle slurry applications corresponded to rates of 0, 96, 240, and 480 kg N ha-1. N leaching was estimated in the lysimeter trial from 1981 to 1991. At a depth of 0.50 m, N leaching was elevated in the plot with the highest slurry application. In October 1991, deeper soil layers (0–10, 10–20, 20–30, 30–40, and 40–50 cm) from control and slurry-amended plots (480 kg N ha-1) were investigated. Soil biological properties decreased with soil depth. N mineralization, nitrification, and enzymes involved in N cycling (protease, deaminase, and urease) were enhanced significantly (P<0.05) at all soil depths of the slurry-amended grassland. High rates of cattle slurry application reduced the weight of root dry matter and changed the root distribution in the different soil layers. In the slurry-amended plots the roots were mainly located in the topsoil (0–10 cm). As a result of this study, low root densities and high N mineralization rates are held to be the main reasons for NO inf3 sup- leaching after heavy slurry applications on grassland.

Mikrobiologische Beurteilung biologischer Bodendekontaminationsverfahren im Modellversuch

Abstract: Fur das Monitoring der biologischen Bodensanierung wurden funf landwirtschaftlich genutzte Boden, die mit n-Tetradekan, 5-CH3-3-Heptanon und Naphthalin (3% w/w) kontaminiert worden waren, verwendet Wahrend der Versuchsdauer von 20 Wochen wurden in regelmasigen Abstanden der Schadstoffgehalt, die mikrobielle Biomasse (SIR), die Dehydrogenaseaktivitat mittels TTC und die N-Mineralisation bestimmt Nach einer kurzzeitigen Hemmung der Dehydrogenaseaktivitat reagierten alle kontaminierten Boden im Vergleich zu den Kontrollboden mit einer Erhohung der mikrobiellen Aktivitat Die N-Mineralisation wurde zu Versuchsbeginn bei vier Boden gehemmt Der Einflus der Kontamination auf die Aktivitat von Bodenmikroorganismen konnte auch nach der mesbaren Eliminierung der Kohlenwasserstoffe festgestellt werden Der Zusatz von Rindenkompost und Rindenmulch beschleunigte die Sanierung eines kalkhaltigen Tschernosems, der mit Heizol (3,8% w/w) kontaminiert worden war Eine Verzogerung der Kohlenwasserstoffeliminierung wurde jedoch bei dem degradierten Tschernosem nach Zusatz von Rindenkompost und Rindenmulch festgestellt Der kontaminierte und mit Strukturmitteln versetzte kalkhaltige Tschernosem wies bei Bezug auf mikrobielle Biomasse (Cmic) eine hohere N-Mineralisation auf als die Kontrollvarianten Die N-Nachlieferung des degradierten Tschernosems wurde durch Kontamination und Zugabe von Rindenmulch wahrend der gesamten Versuchsdauer von 9 Wochen stark gehemmt Die hohe N-Immobilisierung und die Adsorption des Schadstoffes an die Strukturmittel wird als mogliche Ursache fur den verzogerten Schadstoffabbau des degradierten Tschernosems angesehen Microbiological control of the biological decontamination of soils Five agricultural soils which were contaminated with n-tetradecane, 5-methyl-3-heptanone and naphthalene were used to follow the biological clean-up process of these soils The hydrocarbon content, the microbial biomass (substrate-induced respiration), dehydrogenase activity and N-mineralisation were monitored for 20 weeks in the contaminated and control soils Dehydrogenase activity followed similar patterns within various soils, the values being lowest at the beginning of the experiment and highest during the following weeks N-mineralisation of four contaminated soils was reduced at the start of the experiment, but was increased afterwards The influence of contamination on microbial activities was detected even after elimination of the hydrocarbons The addition of compost of bark and pieces of bark increased the biological cleanup process of the Calcic Chernozem contaminated with 3,8% (w/w) fuel oil The addition of both organic materials reduced the decontamination rate of the Haplic Chernozem The ratio of N-mineralisation to microbial biomass of the Calcic Chernozem increased with the addition of compost of bark and pieces of bark, but decreased with the same treatment of the Haplic Chernozem The results of this study suggest that microorganisms immobilize nitrogen in the Haplic Chernozem ammended with pieces of bark to a great extent during the whole experiment The high N-immobilization and the adsorption of hydrocarbons to the added organic material may be the main cause of the slow decontamination of the Haplic Chernozem