Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2002
Sammendrag
Alle som driv med juletre, har erfart at det å produsera eit juletre av god kvalitet ikkje er eit arbeide som gjer seg sjølv. I 8-10 år må felta gjødslast og haldast ugrasreine. Trea må toppskotregulerast og formskjerast. God plantekultur er likevel ingen garanti for å få fram trea. Hovudårsaka til utgang er ulike soppsjukdomar, men skadedyr (til dømes insekt, midd, mus, hare og rådyr) og ubalansert næringstilgong kan også øydeleggja trea. Dessutan spelar været inn. Trea kan få både salt-, vind- og frostskade, spesielt dersom ein ikkje plantar ein planteart eller proveniens som er tilpassa klima på veksestaden. Gjennom prosjektet "Kartlegging og bekjemping av skadegjerarar i klyppegrønt- og juletreproduksjonen" har vi funne årsaka til ein del av dei sjukdomsproblema juletrenæringa slit med. I denne artikkelen vert tre aktuelle skadebilete omtala - skadde røter (rotròte), småplanter som daudar på grunn av soppen Phomopsis og nålefall på større tre.
Forfattere
Trond RafossSammendrag
The present theses deal with the problem of assessing the risk of exotic plant pest introduction following international trade in plants and plant commodities. The general hypothesis of this work was that exotic plant pest introduction risk could be quantified. Whereas this is a multidisciplinary challenge centring on the scientific domains of ecology and statistics, the present exposition had to be constrained to cover some selected parts only of this broad field. A major objective was to study how modern computer intensive methods and statistical methodology could support the combination of different data sources to derive new information about, and in quantifying the magnitude of, and uncertainty in, plant pest introduction risks. Specific attention was also paid to elucidate the characteristics of pest risk assessment as well as the similarities compared to other fields of risk analysis. The general conclusion is that risk assessment is a promising, yet imperfect, approach for solving the problem of plant pest spread and subsequent introduction. Important aspects of the risk assessment approach are its possibility to shed light on the problems of spread of pest organisms, and the resource allocation such a risk assessment study requires. Through a risk assessment study we are enforced to learn more about these problems, and, especially when a quantitative assessment is requested, large gaps in our scientific knowledge may be revealed. These effects of risk assessment would hopefully also be applicable to the general global problem of anthropogenic spread of species and subsequent biological invasions. Sammendraget er redigert.
Sammendrag
Economical and ecological criteria for optimal N fertilization are inherently in conflict, largely due to lack of precise predictions of nitrogen availability as a function of agronomic practice and weather conditions. This problem is particularly pronounced in organic farming, where plant N supply depends on microbial mineralization of organic N such as `green manure". In the present paper, N dynamics after incorporation of a mixture of a green manure material (undersown white clover) and barley straw was investigated in laboratory and field experiments. Nitrogen flows in the soil-plant system were further analyzed with simulation models (COUP: heat- and water transport model, SOILN_NO: soil nitrogen model). Our laboratory experiments showed that the incorporation of a mixture of N-rich white clover material and N-poor barley straw created a transient accumulation of clover derived inorganic N during the first period. Thereafter, microbial N demand during straw C utilization resulted in net immobilization of most of the clover derived inorganic N. As a consequence, the synchronization between net N mineralization and plant N uptake would be better by spring- than autumn incorporation. This was largely confirmed both by measurements and simulations. However, the expected benefit of spring incorporation (ploughing) was counteracted by a large loss (36%) of clover material due to freeze/thaw damage and subsequent surface runoff during the winter. Such winter loss is likely to be a rare phenomenon, however. The results supported our hypothesis that net inorganic N accumulation due to degradation of a clover-straw mixture is transient and that spring incorporation of undersown clover gives a better coincidence of N availability and N uptake by a subsequent crop than does autumn incorporation. Model scenarios showed that ploughing as late as possible in autumn appears to be a good alternative to spring ploughing with regard to N leaching, but early autumn ploughing should be avoided. The study shows that the timing of agronomic operations are important, not only for determining the fraction of inorganic N lost by leaching, but also for the fraction assimilated by microorganisms. In effect, the plants and the microorganisms compete for the same nitrogen, and the success of the plants depend on a proper synchronization.
Sammendrag
Development of environmentally and economically sound agricultural production systems is an important aim in agricultural policy and has a high priority in agricultural research worldwide. The present work uses results from the first complete crop rotation period (1990-1997) of the Apelsvoll cropping system experiment in south-eastern Norway, to discuss the effect of cropping systems and their management practices on environment, soil fertility, crop yields and the farm economy, and how this knowledge may be used to develop a more sustainable agriculture. The experiment includes conventional arable (CON-A), integrated arable (INT-A), ecological arable (ECO-A), conventional forage (CON-F), integrated forage (INT-F) and ecological forage (ECO-F) cropping systems which were established on model farms of 0.2 ha. On the basis of nutrient runoff, soil erosion and pesticide contamination, the following ranking from the most to the least favourable was made for environmental effects: INT-F> ECO-F> ECO-A> INT-A> CON-F> CON-A. Environmental effects such as N and P runoff losses were very much linked to the proportion of ley in the system. Thus, major improvements to reduce the effects of agriculture on nutrient runoff, cannot be achieved without changing the cropping systems in the direction of more mixed farming with reduced cropping intensity. The nutrient balance calculations showed that there were considerable deficits in the ecological systems, a fact which must be taken into consideration in the development of sustainable ecological cropping systems. The yield reduction experienced with integrated and ecological cropping, relative to conventional cropping, was smaller for forage crops and potatoes than for cereals. This suggests that it is easier to maintain the yield level by reduced cropping intensity in mixed farming systems with livestock than in arable farming systems without livestock. Because of the premium prices and government subsidies to ecological farming, the economic results were equally good in the ecological systems as in the conventional ones. Economically, integrated farming was less favourable than the other systems. It is concluded that, overall, integrated and ecological forage systems results in the least environmental harm, and based upon the present government subsidies, the forage systems also seem the most profitable, along with the ecological arable system.
Forfattere
Mehreteab TesfaiSammendrag
Det er ikke registrert sammendrag
Forfattere
Tor Gunnar Vågen E. Yazew N. Haregeweyn F. Kebede S. Haptu K. Gebrekristos R. Pandey V. BallabhSammendrag
This report presents a synthesis of the findings under the Water Harvesting Study (WHS), as part of the Triangular Cooperation Project between Ethiopia, India and Norway. It is the final report as part of phase I of the project. The WHS was first initiated in late 1998 when the first of the field studies was undertaken in Sadguru Water and Development Foundation (SWDF) project areas in Gujarat, India. The findings of this and the other field studies in the villages of Mahudi, Kotda Khurd and Dhabudi (Gujarat), and Adiha and Dibdibo (Tigray) are summarised. The focus of the study has been on water harvesting and integrated watershed management. The field studies have covered various small scale water harvesting systems, including check-dams, river diversion schemes, micro-dams, and a wide range of soil and water conservation measures. The impacts of water harvesting and irrigation systems on soil quality, water quality, yields and the general livelihood of farmers have also been studied. The climatic and hydrological characteristics of the two study regions are presented and the water harvesting approaches of SWDF and REST are outlined. Then the findings of the field studies are presented and discussed for each of the study villages. The depth of the analysis and thus the discussion naturally varies somewhat since this depends on the amount and quality of available data, which varied greatly for the two study regions. Lack of existing data of appropriate quality has been a major challenge throughout the project. Field data collection has been particularly intensive for Tigray since very limited existing data were available for the two villages studied. The implementation of check-dams based on the SWDF design criteria was found to be highly relevant to Tigray. However, these systems need to be adapted to local conditions in Tigray, and more research is needed, particularly related to climate and hydrology, for such a transfer of technology to be successful.
Sammendrag
Uptake in grass crops of ammonium acetate lactate extractable K (KAL) and reserve K (interlayer K + structural K) in soil was studied in 16 field experiments at different locations on a range of mineral soil types in Norway. The K uptake from soil, both from KAL and reserve K, was considerable, often even at the highest level of K fertiliser. During three years, only on the sandy soils with a low level of acid soluble K (KHNO3 minus KAL) was there a yield response to K fertilisation. The KAL values declined rapidly and flattened off at a "minimum level" which differed with soil type. This minimum level for KAL is a useful parameter in fertiliser planning, because the grass usually took up the K in excess of the minimum level over two years. The minimum value of KAL was significantly correlated with the content of clay + silt in soil. The decrease in KAL during the growing season was closely correlated to the KAL value in spring minus the minimum value and, therefore, the amount of K supplied to the grass from the KAL fraction can be calculated. Furthermore, the KAL value for the following spring may be estimated. The release from reserve K was partially related to acid soluble K.
Forfattere
Svein Ole BorgenSammendrag
The article evaluates the usefulness and shortcomings of agency theory as a framework for discussing the future of Norwegian agricultural cooperatives. The first argument is that agency theory ignores the significance of the traditional collective thinking in Norwegian agricultural cooperatives. In this respect, agency theory is incomplete and its explanatory power is low. The second point is that, nevertheless, the value of applying agency theory as a conceptual tool may increase in the close future, due to the emerging of novel industrial strategies and new cooperative forms. Some of the crucial agencyproblems may come to the forefront, and increasingly imprint the agenda of Norwegian agricultural cooperatives.
Forfattere
Helge Lundekvam Eirik Romstad Lillian ØygardenSammendrag
Det er ikke registrert sammendrag
Forfattere
Johannes DeelstraSammendrag
Summary: The report describes the erosion problems in Sub-Basin III, Managua, Nicaragua and proposes measures to alleviate these. Soil loss in the upper part of the catchment causes serious sedimentation in the downstream reaches of the open water courses, resulting in a reduced discharge capacity for water. This in its turn leads to flooding of urban areas during high rainfall periods and under extreme events can lead to closure of the international airport. In addition does the soil loss from agricultural land contribute in the ongoing deterioration of the water quality of Lake Managua while at the same time leading to a decrease in soil fertility and production capacity. An assessment is made of the present soil loss from agricultural land in the Subcuenca III and recommendations are proposed concerning soil conservation measures. Soil loss has been calculated using the Universal Soil Loss Equation (USLE). Very high figures for soil loss were obtained and the question has been raised whether these were realistic. However, the calculations were seriously hampered due to the lack of input data while at the same time were no data were available for validation.. Therefore, also proposals are given for a measurement programme to improve data availability and to be able to verify calculated soil loss. The report is the original to the report " Estudio Agrohidrológico" which is part of the "Estudio Agroecologico y de Drenaje Pluvial de la Subcuenca III de la Cuenca Sur del Lago de Managua" (Agro-Ecological and Rainwater Drainage Study of Sub-Basin III of the Southern Basin of Lake Managua).