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Grass-clover mixtures are essential in many low-N-input cropping systems, but the importance of various root fractions for the below-ground N dynamics are not well understood. This may be due to the difficulties of studying root longevity and turnover in situ in mixtures. The present field study, investigated (1) the development in root biomass over two(More)
We carried out field experiments to investigate if an agricultural grassland mixture comprising shallow- (perennial ryegrass: Lolium perenne L.; white clover: Trifolium repens L.) and deep- (chicory: Cichorium intybus L.; Lucerne: Medicago sativa L.) rooting grassland species has greater herbage yields than a shallow-rooting two-species mixture and pure(More)
Pigeonpea (Cajanus cajan L. Millsp.) is often intercropped with maize (Zea mays L.) in eastern and southern Africa. The studies aimed at determining how different genotypes of pigeonpea responded in terms of grain element composition under farmers’ cropping conditions. Approx. 78 farmers participated. They came from four study sites in Tanzania (Babati and(More)
A bacterial community from Danish agricultural soil was enriched with linuron [N-(3,4-dichlorophenyl)-N'-methoxy-N'-methylurea] as the sole carbon and nitrogen source. The community mineralized [ring-U-14C]linuron completely to 14CO2 and 14C-biomass. Denaturing gradient gel electrophoresis analysis and cultivation revealed that a Variovorax sp. was(More)
Legumes play a crucial role in nitrogen supply to grass-legume mixtures for ruminant fodder. To quantify N transfer from legumes to neighbouring plants in multi-species grasslands we established a grass-legume-herb mixture on a loamy-sandy site in Denmark. White clover (Trifolium repens L.), red clover (Trifolium pratense L.) and lucerne (Medicago sativa(More)
The relationship between sorption strength and degradation kinetics has been studied for the pesticide MCPA in a sandy top- and subsoil. After adding two types of sorbents (crushed peat and activated carbon) in various amounts to the sandy soils, sorption, desorption, and mineralization of 14C-MCPA were measured. The obtained Freundlich constants (KF)(More)
Pesticide mineralization and sorption were determined in 75 soil samples from 15 individually drilled holes through the vadose zone along a 28km long transect of the Danish outwash plain. Mineralization of the phenoxyacetic acid herbicide MCPA was high both in topsoils and in most subsoils, while metribuzine and methyltriazine-amine was always low. Organic(More)
The spatial variability in the mineralisation rate of linuron [N-(3,4-dichlorophenyl)-N'-methoxy-N'-methylurea] was studied within a previously treated Danish agricultural field by sampling soils from eleven different plots randomly distributed across an area of 20 x 20 m. The soils were characterised with respect to different abiotic and biotic properties(More)
A method has been developed for the analysis of (14)CO(2) evolution from the mineralization of (14)C-labelled organic compounds in soil samples. The new method is less space demanding and substantially cuts down laborious manual work compared to the traditional incubation bottle method used. Furthermore, the use of scintillation cocktail is largely reduced(More)
Application of carbon (C) and nitrogen (N) isotopes is an essential tool to study C and N flows in plant-soil-microorganisms systems. When targeting single plants in a community the tracers need to be added via e.g., leaf-labeling or stem-feeding approaches. In this study we: (i) investigated if bicarbonate can be used to introduce 14C (or 13C) into white(More)