Separating NO production and consumption in intact agricultural soil cores at different moisture contents and depths.

Agricultural soils are a major source of the potent greenhouse gas and ozone depleting substance, NO. To implement management practices that minimize microbial NO production and maximize its consumption (i.e.

Edaphic factors and plants influence denitrification in soils from a long-term arable experiment.

Factors influencing production of greenhouse gases nitrous oxide (NO) and nitrogen (N) in arable soils include high nitrate, moisture and plants; we investigate how differences in the soil microbiome due to antecedent soil treatment additionally influence denitrification. Microbial communities, denitrification gene abundance and gas production in soils from tilled arable plots with contrasting fertilizer inputs (no N, mineral N, FYM) and regenerated woodland in the long-term Broadbalk field experiment were investigated. Soil was transferred to pots, kept bare or planted with wheat and after 6 weeks, transferred to sealed chambers with or without KNO fertilizer for 4 days; NO and N were measured daily.

Understanding spatial variability of soil properties: a key step in establishing field- to farm-scale agro-ecosystem experiments.

Rationale: The spatial variability of soil properties is poorly understood, despite its importance in designing appropriate experimental sampling strategies. As preparation for a farm-scale agro-ecosystem services monitoring project, the 'North Wyke Farm Platform', there was a need to assess the spatial variability of key soil chemical and physical properties.

Methods: The field-scale spatial variability of soil chemical (total N, total C, soil organic matter), soil physical properties (bulk density and particle size distribution) and stable isotope ratios (δ(13) C and δ(15) N values) was studied using geostatistical approaches in an intensively managed grassland.

Stable carbon isotope analysis of fluvial sediment fluxes over two contrasting C(4) -C(3) semi-arid vegetation transitions.

Rationale: Globally, many drylands are experiencing the encroachment of woody vegetation into grasslands. These changes in ecosystem structure and processes can result in increased sediment and nutrient fluxes due to fluvial erosion. As these changes are often accompanied by a shift from C(4) to C(3) vegetation with characteristic δ(13) C values, stable isotope analysis provides a promising mechanism for tracing these fluxes.

Long-term release of carbon from grassland soil amended with different slurry particle size fractions: a laboratory incubation study.

Application of animal manure to agricultural soils enhances both native soil carbon (C) and overall (native soil C and added C) respiration. CO(2) effluxes were measured in a laboratory incubation study for 1465 days after the application of different slurry fractions (>2000, 425-2000, 250-425, 150-250, 45-150 and <45 µm) to a grassland soil. The slurry-derived C present in the soil was traced using the natural abundance δ(13)C method.