Arne Oddvar Skjelvåg

A GIS-based agro-ecological decision system based on gridded climatology

The introduction of GIS has opened up new possibilities in combining different sources of geographical information. In Norway, an agro-meteorological decision system is under development which combines gridded weather information with soil and crop development data. The system is based on a daily scale soil moisture model driven by meteorological inputs. Weather information is based on in-situ observations, and spatial interpolation schemes are used to establish fine-mesh grids of these variables over the model domain. These interpolation schemes take advantage of geographical co-variables such as terrain information. The soil moisture model is used to estimate the soil water content, which is the determinant of soil suitability for tillage and sowing. The system also includes a phenological model for identification of suitable days when combine-harvesting of cereals can be satisfactorily undertaken. Spatial interpolation of the meteorological elements is based upon all available in-situ observations. The different elements are interpolated by different interpolation techniques. Snow depth, cloud cover, relative humidity and wind are in this first version, interpolated by using inverse distance weighting. Precipitation is determined by triangulation with elevation adjustment. Temperature is interpolated by using a residual kriging approach that includes five independent predictors in the trend equation. Evaporation is estimated by using the Penman2 formula based on the estimates of the meteorological elements. This approach is a good demonstration of the benefits of applying GIS and distributed geo-data in cross-disciplinary situations. The application is a valuable contribution to soil capability assessments. Copyright

Environmental life cycle assessment of cereal and bread production in Norway

Abstract We assessed the environmental impacts of producing bread, as delivered to the consumer, assuming the use of Norwegian ingredients only. Ten impact categories, including global warming potential (GWP), were quantified by mixed modelling and life cycle assessment. Firstly, we quantified the impacts of growing barley, oats, winter and spring wheat on 93 farms that were representative of the main cereal production regions in Norway. We used wide system boundaries, which included all relevant processes occurring both pre-farm and on-farm. Secondly, we assessed a representative production chain for bread, including transport, milling, baking and packing processes. On-farm processes accounted for a large share of the environmental impacts attributable to the production of bread (e.g. 50% for GWP). There is thus considerable potential for environmental improvements through changes in farm management. In total, the GWP per kg of bread (freshweight) was 0.95 kg CO2-equivalent. The environmental footprint of transport was small.

Nitrogen fertilization to broccoli cultivars at different planting times: Yield and nitrogen use

Abstract The effects of three nitrogen (N) fertilizer rates (0, 120, and 240 kg N ha−1) and two planting times (May or late June/July) on yield and N use of the early cultivar ‘Milady’ and the late cultivar ‘Marathon’ of broccoli (Brassica oleracea var. italica) were investigated on three silty loam soils varying in soil mineral N (Nmin) in the southernmost part of Norway during 1999 and 2001. In all crops receiving fertilizer, rapid uptake of N started about three weeks after planting. The relative yield of broccoli heads increased with increasing soil available N (fertilizer N plus Nmin) at planting to 200–250 kg N ha−1 and then levelled off. The two lower fertilizer rates were more restrictive to yields in early-planted than in late-planted crops. A general increase in harvest index with increasing N rate reflected a stronger effect of N on the head yield than on the total above ground biomass production. The apparent recovery of fertilizer N decreased with increasing N rate and was on average 74% in total above ground biomass and 25% in broccoli heads. Despite a higher N uptake, the average soil mineral N level at harvest increased from 12 kg N ha−1 on unfertilized plots to 27 and 78 kg N ha−1 on plots receiving 120 and 240 kg N ha−1, respectively; this increase was stronger in early than in late plantings and stronger in ‘Milady’ than in ‘Marathon’. The yield of broccoli heads was similar in the two cultivars, but ‘Milady’ had a lower total biomass production and thus a higher harvest index, presumably due to earlier head initiation.

The Phenological Development of Oat (Avena sativa L.) Cultivars as Affected by Temperature and Photoperiod

Abstract Six cultivars from ca. 40 to 67° N were subjected to 12, 16 and 24 h photoperiod and 9, 12, 15, 18 and 21°C constant temperature. A common, multiplicative model of temperature and photoperiod proved suitable for describing their combined effect on the rate of development of all cultivars. With 16 and 24 h photoperiod a single cultivar factor, determined by the average difference in earliness, accounted for cultivar differences both in earliness and in response to temperature and photoperiod. Response to photoperiod before heading was strongest in the Northern European cultivars. A gradual change in response took place during ripening such that, from yellow to full ripeness, shorter days increased the rate of development. After-effects of temperature before booting on the rate of development in the ripening phases were evaluated in a separate experiment, and were most pronounced at extreme temperatures.

Model prediction of frost tolerance as related to winter survival of wheat in Finnish field trials

The model FROSTOL simulates course of frost tolerance in winter wheat on a daily basis from sowing on as affected by soil temperature (2 cm), snow cover, phenological development, and a genotypic maximum level of frost tolerance (LT50). A series of cultivar trials in Finland was used to evaluate the models ability to estimate plant survival in natural field environments during winters with differing weather conditions. Recorded survival was compared with number of intersections between the curves of simulated LT50 and the soil temperature curve for each field. A cumulative stress level (CSL) was calculated based both on number of intersections and FROSTOL simulated stress levels. The correlation between CSL and field recordings was quite low. While the field trials characterize a general ability to stand various types of winter stress, FROSTOL estimates damage caused by the soil temperature regime only. However, FROSTOL simulations seemed to correspond reasonably well to field observations when low temperature was the eventual cause of damage.

The relationship between frost tolerance and generative induction in winter wheat (Triticum aestivum L.) under field conditions

The quantitative nature of the vernalization and photoperiod requirements and the interference of plant age with these mechanisms complicate predictions of generative induction and its relation to frost tolerance. This study was designed to dissect further the course of development towards full generative induction and to time the stages in frost tolerance. Two cultivars of winter wheat were regularly sampled from fields at four sites during three winters. The apex stage of development was observed at time of sampling and after 3 subsequent weeks of growth at 18°C, under either short or long days. Level of frost tolerance at sampling was also recorded. No visible change in apex appearance was found at time of sampling, but readiness of plants to initiate generative development was enhanced. Vernalization by low temperatures alone was not enough to induce the plants into generative development or initiate loss of frost tolerance. Short day conditions after sampling delayed the appearance of double ridges b...

Water soluble carbohydrates and growth potential of winter wheat as influenced by weather conditions during winter

Abstract Although winter survival of winter wheat most often is recorded qualitatively by rating dead or living plants, the surviving plants may differ extensively in vigour and degree of carbohydrate reserves left at the end of winter. This factor is yet not accounted for in existing models of winter wheat yield and crop performance. A quantitative measure of plant vigour at spring arrival, as influenced by the prevailing winter weather and the plants’ concentration of water soluble carbohydrates, would hence make a useful supplement to such models. Two cultivars of winter wheat were grown in boxes over 2 years at three sites in Norway with contrasting winter climates. Plants were sampled monthly for measurements of growth potential and analyses of reserve carbohydrates. Fructan constituted the main part of water soluble carbohydrates (WSC). The concentration of fructan fell throughout winter, but increased rapidly after snow thaw in spring when a positive carbon balance was restored. Daily global radiation at plant level and soil temperature (2 cm) were the only two climatic factors found to have significant effects on periodic changes in fructan concentration in a stepwise regression analysis. Still, number of days with snow cover had a causal effect through its impact on soil temperature and radiation at plant level. In neither of the 2 years was there any significant correlation between plant carbohydrate concentration and growth potential at the different sites. The results implied that plant vigour at the end of winter was strongly related to plant condition in late autumn and duration of snow cover in winter. Plants that had been covered with snow for a long time period showed significantly lower growth at the samplings in March and April than plants from the location with a shorter duration of snow cover.

Estimating farm-scale greenhouse gas emission intensity of pig production in Norway

Abstract To assess greenhouse gas (GHG) emission intensity and its variation in Norwegian pig production, we conducted an analysis of 15 farrow-to-finish pig farms to calculate farm-scale emissions of GHGs, expressed as carbon dioxide equivalents (CO2eq) per kg carcass weight (CW) sold. A model, HolosNor, was developed to estimate net GHG emissions, including soil C changes, from pig farms. Based on data from 2008 the estimated GHG intensity was 2.65 kg CO2eq kg−1 CW (range: 1.24–4.03). The production of the feed consumed by the pigs contributed most to total GHG emissions; accounting for 2.14 kg CO2eq kg−1 CW, or more than 80% of the total emissions. Our study estimated a large variation in GHG intensity among pig farms in Norway which indicates opportunity for incorporating mitigation practices. A valuable contribution of the current work is the framework of a farm-scale tool for assessing farm-specific mitigation options.

Farm specific natural resource base data for estimating greenhouse gas emissions

Abstract Models for an holistic analysis of a farms greenhouse gas (GHG) emissions are available, e.g. HolosNor. They require access to a farms management data and its soil and climatic conditions. The objective of this investigation was to demonstrate how available soil and climatic data can be used to provide the required inputs of a farms natural resource base. Soil type recordings from six municipalities representing main agroclimatic zones of Norway were used. By means of a soil moisture model a combined index of soil moisture and temperature was estimated for use in a carbon balance model, also taking crop species into account. Water filled pore space (Wfps) to saturation and soil temperature were estimated for calculation of emission of nitrous oxide. Input variables for calculation of GHG emissions varied considerably among municipalities and among farms therein.