Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
1999
Authors
O. Janne Kjønaas Anne Camilla Bergkvist Arne Olav StuanesAbstract
No abstract has been registered
Authors
Tonje Økland Rune Halvorsen Økland Eiliv SteinnesAbstract
No abstract has been registered
Authors
Svein Ole BorgenAbstract
No abstract has been registered
Authors
Svein Ole BorgenAbstract
No abstract has been registered
Authors
Per Ivar Våje Bal Ram Singh Rattan LalAbstract
Nitrogen and water are both major limiting factors for agronomic production in Africa. The effect of erosion on the availability of N and water for plants is not known for major soils of the tropics. Therefore, a study was conducted to assess erosional effects on N- and water-balance on a Mollic Andosol of 9-17% slope at Lyamungu Agricultural Research and Training Institute (ARTI), Kilimanjaro region, Tanzania. Soil erosion phases were established on the bases of the topsoil depth (TSD) as an indicator of previous erosion: <1 cm; severely eroded, 16-25 cm; moderately eroded and 26-35 cm; slightly eroded. Fill-in lysimeters (80 cm diameter, 80 cm deep) and field runoff plots (4x10 m) were used to monitor evapotranspiration (ET) and seepage, and N losses through erosion, runoff leaching and plant uptake. Maize (Zea mays var. Kilima) was planted in lysimeters and runoff-plots over two cropping seasons (1995 and 1996). Rainfall and evaporation (E) were measured daily. Sediment samples from runoff plots were analysed for total N, P and C, and water samples from leachate, runoff, and
Authors
O. Janne KjønaasAbstract
No abstract has been registered
Authors
O. Janne KjønaasAbstract
Mixtures of cation and anion exchange resins are used as part of the resin core technique to determine nitrogen transformation in forest soils as they adsorb the NH4-N and NO3-N from soil solution percolating through the incubated soil cores. In the field, the exchange resins may be subjected to a variety of conditions, involving drying, rehydration, freezing, and thawing. This paper examines how these processes affect adsorption of NH4-N and NO3-N and the stability of the resins. Lab tests were performed on the anion resin Amberlite IRA-93, the cationresin Amberlite IR-120, and a mixture of IRA-93 and IR-120, and the commercially-mixed bed resin Amberlite MB1. The background content of NO3-N and NH4-N on the resins was large and highly variable between different batches of resins in spite of a 2 M NaCl pre-rinse. The IR-120 cation resin that was subjected to 48 hours air-drying contained significantly less NH4-N than the most resins, while the drying of the IRA-93 anion resin caused a significant release of NO3-N from resins with no N addition. Although the variation was large, the mixed bed resin MB1 indicated a release of NH4-N, which supports results from long term in situ deployments. A reduced adsorption of NO3-N was found on the IRA-93 anion resins and the MB1 mixed bed resins that were dried prior to N addition while the dry IR-120 cation resins adsorbed significantly less NH4-N than the control resin. No effect of freezing the thawing efficiency was observed on resin stability or N adsorption efficiency. Sufficient blanks that have been subjected to similar moisture changes are necessary in N limited systems with low levels of avialable NH4-N and NO3-N.
Authors
Mehreteab TesfaiAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
A.D. Bila D. LindgrenAbstract
No abstract has been registered