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.
1999
Sammendrag
This report focuses on agriculture and its impacts in rural areas. Agriculture is an important activity in the Norwegian periphery, directly and indirectly. A deregulation of agriculture will most probably have negative impacts on agricultural production and employment. This, in turn, will have negative impacts on other sectors. Since agriculture is overrepresented in the periphery, and there are few alternative sources of employment, reduced activity in agricultural can lead to increased centralisation. This can be a problem since the relatively low population densities already imply a danger of depopulation in the periphery. Some motivations for regulating agriculture are based on the sector's importance in the periphery. Regulations are also motivated by other facts. It is very difficult to distinguish precisely between rurality and other motivations. However, part of the motivation is agricultural production itself, or aims that can be deducted from production. Distribution of income is an example of this. From a theoretical point of view, subsidies should, in order to be as efficient as possible, be directed directly towards the problems they are meant to cure. If the aim for granting agricultural support is rural development and not agricultural production, then it is better to grant subsidies that do not depend upon production. Rural development (RD) can be thought of as complementary to agricultural production (AP): (*) RD = f(AP), f'(AP) > 0 This means that you get more RD if AP increases, and less RD if AP decreases. By subsidising AP, you will automatically get more RD. The function (*) does not, however, say anything about the efficiency of subsiding AP for gaining RD, compared to using the same amount of subsidies directly at gaining RD. The function does not describe whether subsidies that are production dependent are preferable to non-production subsidies from a rural development point of view. Using the function (*) and the fact that the secondary effects of reducing agricultural subsidies may be substantial in the peripheries, one may argue, however, that agriculture is important and that agricultural production is an essential industry for rural development. We would also like to underline the fact that agricultural has several non-food impacts and that multifunctionality is much more than rural development. It is especially difficult to distinguish between «rural development» and «cultural landscape». The relationship between them should probably be discussed further.
Forfattere
Ricardo Holgado Christer MagnussonSammendrag
Nematodes (roundworms) are microscopic vermiform animals. Most nematodes live in soil or in fresh water and marine sediments. Nematodes (Phylum Nematoda) has experienced more than 600 million years of evolution and form 80% of the multicellular animals on planet earth. The population densities of nematodes often reach several million individuals per m2. Most species are free-living, feeding on microorganisms, microscopic plants and animals. Numerous species, however, are parasites of humans, animals and plants. Nematodes may be beneficial to man as regulators of nutrient cycling or as parasites of insect pests. The study of plant parasitic nematodes, nematology, is a young scientific dicipline. Although, the first plant parasitic nematode, i.e. the wheat seed-gall nematode Anguina tritici, was observed as early as in 1743, nematology as a science did not develop until the second half of the 19th century. The economic impact of nematodes as parasites of agricultural crops was recognised as late as in the 1940:ties, and was a consequence of the increased use of chemicals. The economic loss caused by nematodes to world agriculture may amount to 80 billion US$ annually. Plant parasitic nematodes are of particular importance in tropical and subtropical regions of the world. At present the full importance of these parasites may be much underestimated due to the frequent use of nematicides. However, as a result of future restrictions in the use of chemical treatments against nematodes, the damage caused by these parasites can be expected to increase dramatically. Future successful management of both harmful and beneficial nematodes would require increased knowledge of nematode biology. This can only be achieved by an increased research and education in nematology.
Forfattere
Torstein KvammeSammendrag
Det er ikke registrert sammendrag
Forfattere
T.K Haraldsen Åsmund Asdal C Grasdalen Lars Nesheim T.N UglandSammendrag
Det er ikke registrert sammendrag
Forfattere
Åsmund Asdal Anne Kjersti BakkenSammendrag
Det er ikke registrert sammendrag
Sammendrag
There is growing interest in production of arable crops on organic farms with few or no livestock. This calls for more detailed knowledge on how to optimize the fertilization effect from preceding crops. As part of a research programme started in 1998 we are studying to what extent undersown clover can supply successive grain crops with neccessary nutrients, in particular nitrogen (N). We are also examining if and how release of N can be manipulated, in order to synchronize it with the N demand. In this paper we discuss central hypotheses and present some preliminary results from experiments with undersown clover crops. Considerable amounts of N (50-90 kg ha -1) were found in above ground clover biomass in a field experiment with undersown clover. In a laboratory experiment, above ground biomass of clover and straw (harvested in autumn) was mixed into the soil in amounts proportional to the measured field yields. This resulted in an insignificant net N mineralization during the first 80 days. The reason was immobilization of N during straw decomposition. By day 160, however, considerable amounts of N were remineralized. In a following experiment, both above and below ground biomass of clover and straw (harvested in spring) was incubated. This resulted in net N mineralization from the start of the incubation. Probably, mineralization of straw C during winter had reduced the N immobilization potential. We hypothesize that the N effect of clover subcrops, in principle, can be improved by separating in time straw C mineralization from clover N mineralization. We also speculate that this can be implemented in farming practices. Moreover, roots were disregarded in the first experiment, but included in the second. In a third incubation experiment, with red clover, we found that root N contributed with 30% of mineralized N from the clover biomasss after 25 days. Thus, root-derived inorganic N may explain the differences between the two first experiments.When assessing the N effect of crop residues on successive plant growth, root N and root degradability must, therefore, be taken into consideration. In organic arable crop systems with small amounts of animal manure, microbial fixation of atmospheric N must be maximized and losses of N from the system must be minimized. This is the subject of further research in this programme.
Forfattere
L ReitanSammendrag
Det er ikke registrert sammendrag
Forfattere
Steinar DraglandSammendrag
Det er ikke registrert sammendrag
Sammendrag
En ny spinnmidd (Eotetranychus lewisii) er funnet i julestjerne i norsk veksthus. I Europa er denne midden hittil bare kjent fra Tyskland. Artikkelen inneholder informasjon om utbredelse, vertplanter, biologi, utseende og bekjempelse
Forfattere
Sverre KobroSammendrag
Invitasjon til urtedyrkere om å sende inn skadeinsekter til identifikasjon, for å komme i forkant av senere problemer