Marianne Bechmann
Research Professor
(+47) 412 19 506
marianne.bechmann@nibio.no
Place
Ås O43
Visiting address
Oluf Thesens vei 43, 1433 Ås
Attachments
CV per September 2018Biography
Abstract
This report describes the development of models to calculate losses of soil particles, phosphorus, nitrogen and organic carbon from agricultural land to first order streams. The results from the models serve as input data to the TEOTIL model which estimates the net losses from agriculture and all other sources. The agricultural models (AGRITIL) were calibrated for catchments in the Agricultural Environmental monitoring programme and are limited by the availability of data for different regions in Norway.
Abstract
In agricultural areas dominated by subsurface drainage, leaching of phosphorus (P) from soils is a concern for downstream water quality. Still, the role of chemical processes in subsoils and organic soils in influencing dissolved P leaching needs to be clarified for better predicting the P leaching. In ten mineral and organic soils, we examined a wide range of chemical characteristics including various P pools and sorption–desorption properties at different soil depths and related those characteristics to leaching of dissolved P at the drain depth in an indoor lysimeter experiment. Results showed significant correlations between different P pools (R2-adj = 0.61 to 0.98, p < 0.001) and between sorption capacity measurements (R2-adj = 0.60 to 0.95, p < 0.001). Some organic soils followed the same patterns in P sorption capacity and P lability as sandy soils but some did not, suggesting organic soils differ among themselves possibly due to differences in origin and/or management. Flow-weighted mean concentrations of dissolved reactive P and dissolved organic P depended on both the labile P pools (labile inorganic and organic P pools, respectively) in the topsoil and P sorption and desorption characteristics in the subsoils. Mass-weighted whole-profile degree of P saturation based on the ammonium lactate extraction method (DPS-AL) was an excellent indicator of flow-weighted mean concentration of total dissolved P (FWMC-TDP) (R2-adj = 0.93, p < 0.001). Two profiles, one with organic soils overlaying on sand and the other with sandy soils in all layers, had the greatest FWMC-TDP among all profiles (316 and 230 µg/L versus 33–84 µg/L) due to the same reason, i.e., large labile P pools in the topsoils, low P sorption capacity in the subsoils, and high whole-profile DPS-AL. All results point to the need to include subsoil characteristics for assessing the risks of dissolved P leaching from both mineral and organic soils. Also, the study suggests the need to investigate further the roles of the origin and management of organic matter and organic P in influencing P lability and dissolved organic P (DOP) leaching, as well as the bioavailability of DOP in recipient waters.
Abstract
No abstract has been registered
Division of Environment and Natural Resources
Nutrient balances and use efficiencies for the Timebekken catchment
Grass-based livestock production is important for economy in Rogaland, but concerns are increasingover soil nutrient surplus that contribute to degraded water quality in downstream water bodies. Inthis project, we will improve the understanding of nutrient balances and use efficiencies in Rogalandby measuring grass yield, nutrient contents in grass and total nutrient removal through cropregistration and nutrient analyses in 15 representative fields over two years in the Timebekkencatchment.
Division of Environment and Natural Resources
Mitigation measures for phosphorus and nitrogen under changing climate: conflicts and synergies
Nutrient concentrations, loads and stoichiometry (i.e., N:P ratio) in agricultural runoff affect the quality of surface waters. In Norway, the reduction of nutrient runoff is challenged by the sloped landscape, variable weather and changing climate with an increasing number of extreme hydrological events. Mitigation measures for reducing nutrient losses are pressingly needed but they do not always work simultaneously or equally for both N and P, due to the differences in their agronomic and biogeochemical characteristics and dominant transport pathways.
Division of Environment and Natural Resources
Climate- and environmentally friendly use of animal manure
There is a need to update knowledge about the utilization and loss of nitrogen and phosphorus from livestock manure in order to assist the authorities and the agricultural industry in meeting climate and environmental targets. There is a major focus on the use of phosphorus, phosphorus content in soil and runoff to waterways in connection with the revision of the fertilizer regulations. The time and method of spreading livestock manure, as well as the total amount of manure used, are important factors that influence the loss. Reduced ammonia volatilization and runoff of nitrogen reduces indirect nitrous oxide losses from livestock manure, but also direct and indirect nitrous oxide emissions through reduced use of mineral fertiliser. The project includes a literature compilation and field measurements to measure the utilization of nutrients at different spreading times for livestock manure in different parts of the country. In the project, field measurements will be made on the effect of different spreading times on the utilization of nitrogen and phosphorus for plant growth. The field measurements are carried out in Rogaland, Vestland and Trøndelag county.
Division of Food Production and Society
ECONUTRI
Innovative concepts and technologies for ECOlogically sustainable NUTRIent management in agriculture aiming to prevent, mitigate and eliminate pollution in soils, water and air
Division of Food Production and Society
Agricultural mitigation measures and the value of water quality improvements
Agriculture is one of the main sources of water pollution in Norway, and an important contributor to GHG emissions.