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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.

2012

Abstract

Climate and weather variability affect agricultural crop production. The North Atlantic Oscillation (NAO) is the variation in air pressure difference in the northern Atlantic Ocean. A positive NAO index with higher than normal air pressure near the Azores and lower than normal near Iceland results in warm and wet winters in northwestern Europe. A negative NAO index gives opposite climatic effects in this region. We determined the effect of the NAO on the risk of frost injury in winter wheat for conditions that represent northwestern Europe by applying the FROSTOL model to dynamically simulate hardening, de-hardening and other physiological processes determining frost tolerance and frost injury in winter wheat. This model uses soil surface temperature and snow cover as driving variables. In total, 53 winter seasons from 1957-58 to 2009-10 were simulated to account for historical trends and variations in the NAO. Monthly and seasonal mean NAO indices for all years within this period were categorised into positive, neutral or negative phases. The winter wheat simulations included 3 locations in Norway (Apelsvoll, ås and Kvithamar), 2 wheat frost tolerance types and 3 planting dates. The results showed that negative NAO phases, especially in February and March, increased the risk of frost injury in winter wheat. The risk of frost injury was higher at Apelsvoll and ås than at Kvithamar, especially in negative NAO phases or after early planting. The results obtained can be used to design crop management practices and systems with higher production security.

Abstract

The current IPCC guidelines define an estimate for the fraction of mineral fertilizer and animal waste (manure) lost to leaching and runoff (FracLEACH). The FracLEACH default is 30 %. In Norway, 18 % has been used based on calculations made in 1998 (Vagstad et al., 1998). The main purpose of this study was to give an updated estimate of nitrogen (N) leaching in relation to the amounts of N applied in agriculture (FracLEACH). The term losses in this report include both surface and subsurface runoff. The estimates of FracLEACH presented in this report were based on data from the Agricultural Environmental monitoring program (JOVA). The JOVA-program includes catchment and field study sites representing typical situations in Norwegian agriculture with regard to production system, management, intensity, soil, landscape, region and climate. Data from plot- scale study sites confirmed the level of N leaching from the agricultural areas within the JOVA catchments. The overall FracLEACH estimated in this study was 22 % of the N applied. This average covers a variation between sites from 16 % on grassland in Valdres to 44 % in intensive vegetable, potato and cereal production areas in the southernmost part of Norway. Runoff is the most significant parameter for the difference in FracLEACH between catchments. In addition, production system and to some degree soil type are important for FracLEACH. It is thus suggested to use different FracLEACH-values for the different production systems and adjust FracLEACH according to average runoff for the region.

2011

Abstract

The anticipated future changes in temperature, precipitation and snow cover caused by global warming may affect winter survival of autumn sown wheat. More variable weather conditions may cause an increased frequency of periods with alternating freezing and thawing and less stable snow covers. In the present study, the course of plant frost tolerance and growth potential was studied by exposing cold acclimated plants of winter wheat to conditions with alternating periods of freezing and thawing (either -1 °C or +5 °C), and differing durations of snow cover. Tests of frost tolerance and determination of growth potential were performed each time the temperature or snow cover conditions were changed. Periods without snow cover and + 5 °C caused dehardening, with loss of frost tolerance being more pronounced during the first dehardening period than in the second one. The ability to reharden after a dehardening period decreased towards the end of the experimental period. Mild periods during winter also seemed to exhaust plant growth potential, possibly by increasing respiration rate while photosynthesis was still restricted. The results indicate some of the challenges we may face regarding overwintering of winter wheat in a future climate.