Tommy Dalgaard

A model for fossil energy use in Danish agriculture used to compare organic and conventional farming

Knowledge about fossil energy use in agricultural systems is needed, because it can improve the understanding of how to reduce the unsustainable use of limited energy resources and the following greenhouse gas emissions. This study describes and validates a model to assess fossil energy use in Danish agriculture; gives an example of how the model can be used to compare organic and conventional farming; and discusses the implications and potentials of using the model to simulate energy use in scenarios of agricultural production. The model is a development of an existing model, which was too coarse to predict measured energy use on Danish farms. The model was validated at the field operational, the crop type, and the national level, and can supplement the Intergovernmental Panel on Climate Change manual to quantify fossil energy use and subsequent carbon dioxide emissions from agriculture. The model can be used to model energy use as one indicator in a multi-criteria evaluation of sustainability, also including other agroecological and socio-economic indicators. As an example, energy use for eight conventional and organic crop types on loamy, sandy, and irrigated sandy soil was compared. The energy use was generally lower in the organic than in the conventional system, but yields were also lower. Consequently, conventional crop production had the highest energy production, whereas organic crop production had the highest energy efficiency. Generally, grain cereals such as wheat have a lower energy use per area than roughage crops such as beets. However, because of higher roughage crop yields per area, energy use per feed unit was higher in the roughage crops. Energy use for both conventional cattle and pig production was found to be higher than that for organic production. With respect to fossil energy use per produced livestock unit, agro-ecosystems producing pigs were in both cases less energy effective than those producing cattle. Fossil energy use for three scenarios of conversion to organic farming with increasing fodder import was compared to current conventional farming in Denmark. The scenario with the highest fodder import showed the highest energy use per livestock unit produced. In all scenarios, the energy use per unit produced was lower than in the present situation. However, the total Danish crop production was also lower. In conclusion, the model can be used to simulate scenarios, which can add new information to the discussion of future, sustainable agricultural production.

Agroecology, scaling and interdisciplinarity

Abstract Based on a review of its history, its present structure and its objective in the future, agroecology is defined as an integrative discipline that includes elements from agronomy, ecology, sociology and economics. Agroecology’s credentials as a separate scientific discipline were measured against the norms of science, defined by Robert King Merton (1973): communalism, universality, disinterestedness, originality and doubt. It is concluded that agroecology meets many of these norms and where it differs, it does so in a way that perhaps anticipates the manner and the direction in which the social position of science is changing. Accepting agroecology as a separate scientific discipline, the two main issues with which it must contend were considered to be those of scaling and interdisciplinarity. Scaling is a problem because results of agroecological research are typically generated at small spatial scales whereas applications are frequently implemented in larger, administrative units. A framework to convey information from science to decision-makers was proposed and tested in a case study of farm energy use. Interdisciplinarity is a problem because researchers from different disciplines see the world from different viewpoints, use different language, work at different locations and use different criteria to evaluate one another’s work. Progress in this area is likely to be slow and driven by the need to justify the value of science to society.

Policies for agricultural nitrogen management—trends, challenges and prospects for improved efficiency in Denmark

With more than 60% of the land farmed, with vulnerable freshwater and marine environments, and with one of the most intensive, export-oriented livestock sectors in the world, the nitrogen (N) pollution pressure from Danish agriculture is severe. Consequently, a series of policy action plans have been implemented since the mid 1980s with significant effects on the surplus, efficiency and environmental loadings of N. This paper reviews the policies and actions taken and their ability to mitigate effects of reactive N (Nr) while maintaining agricultural production. In summary, the average N-surplus has been reduced from approximately 170 kg N ha?1 yr?1 to below 100 kg N ha?1 yr?1 during the past 30 yrs, while the overall N-efficiency for the agricultural sector (crop?+?livestock farming) has increased from around 20?30% to 40?45%, the N-leaching from the field root zone has been halved, and N losses to the aquatic and atmospheric environment have been significantly reduced. This has been achieved through a combination of approaches and measures (ranging from command and control legislation, over market-based regulation and governmental expenditure to information and voluntary action), with specific measures addressing the whole N cascade, in order to improve the quality of ground- and surface waters, and to reduce the deposition to terrestrial natural ecosystems. However, there is still a major challenge in complying with the EU Water Framework and Habitats Directives, calling for new approaches, measures and technologies to mitigate agricultural N losses and control N flows.

Trend reversal of nitrate in Danish groundwater--a reflection of agricultural practices and nitrogen surpluses since 1950.

This paper assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. First, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribution, trends, and trend reversals in the groundwater nitrate concentration. Second, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Third, groundwater recharge CFC (chlorofluorocarbon) age determination allows linking of the first two data sets. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater. Regulation and technical improvements in the intensive farming in Denmark have succeeded in decreasing the N surplus by 40% since the mid 1980s, while at the same time maintaining crop yields and increasing the animal production of especially pigs. Trend analyses prove that the youngest (0-15 years old) oxic groundwater shows more pronounced significant downward nitrate trends (44%) than the oldest (25-50 years old) oxic groundwater (9%). This amounts to clear evidence of the effect of reduced nitrate leaching on groundwater nitrate concentrations in Denmark.

Developments in greenhouse gas emissions and net energy use in Danish agriculture – How to achieve substantial CO2 reductions?

Greenhouse gas (GHG) emissions from agriculture are a significant contributor to total Danish emissions. Consequently, much effort is currently given to the exploration of potential strategies to reduce agricultural emissions. This paper presents results from a study estimating agricultural GHG emissions in the form of methane, nitrous oxide and carbon dioxide (including carbon sources and sinks, and the impact of energy consumption/bioenergy production) from Danish agriculture in the years 1990-2010. An analysis of possible measures to reduce the GHG emissions indicated that a 50-70% reduction of agricultural emissions by 2050 relative to 1990 is achievable, including mitigation measures in relation to the handling of manure and fertilisers, optimization of animal feeding, cropping practices, and land use changes with more organic farming, afforestation and energy crops. In addition, the bioenergy production may be increased significantly without reducing the food production, whereby Danish agriculture could achieve a positive energy balance.

Multifunctional agriculture and multifunctional landscapes - land use as an interface

In contemporary sciences dealing with cultural landscapes, the concept of multifunctionality has gained increasing attention in the last decade. The scientific literature displays several attempts to frame the concept (e.g DeVries 2000; Anon 2001; de Groot et al. 2002) but there is much frustration regarding proper sets of broadly based definitions and clear statements concerning the authors’ scientific points of departure (Anon 2001). Multifunctionality is on the one hand used to characterize the activities in the primary production sector, and the land use reflecting the material consequences of the various demands set by the society on land territories — these approaches relate to the agricultural understanding of multifunctionality. On the other hand, multifunctionality is used to characterize the landscape per se. The primary production sector (i.e. agriculture, forestry, horticulture and related land dependent activities) is considered having a primary or main function (production), and related joint productions, typically including a mix of material and non-tangible goods as well as a mix of private and public goods (externalities). Production of food and fibres is generally considered the primary products in this context, but the primary sector produces other material goods too, such as CO2 sequestration, groundwater recharge etc.

Topographically controlled soil moisture is the primary driver of local vegetation patterns across a lowland region

Topography is recognized as an important factor in controlling plant distribution and diversity patterns, but its scale dependence and the underlying mechanisms by which it operates are not well understood. Here, we used novel high-resolution (2-m scale) topographic data from more than 30500 vegetation plots to assess the importance of topography for local plant diversity and distribution patterns across Denmark, a 43000 km2 lowland region. The vegetation data came from 901 nature conservation sites (mean size = 0.16 km2) distributed throughout Denmark, each having an average of 34 plots (five-meter radius) per site. We employed a variety of statistical measures and techniques to investigate scale dependence and mechanistic drivers operating within the study region. Ordinary Least Squares (OLS) multiple regression modeling scaled at different spatial resolutions (2 × 2, 10 × 10, 50 × 50, 100 × 100 and 250 × 250 m) was used to identify the horizontal resolution yielding the strongest vegetation–topography ...

Energy self-reliance, net-energy production and GHG emissions in Danish organic cash crop farms

Organicfarming(OF)principles include the idea of reducing dependence of fossil fuels, but little has been achieved on this objective so far in Danish OF. Energy use and green house gas (GHG)emissions from anaverage 39 ha cash crop farm were calculated and alternative crop rotations for bio-energy production were modeled. Growing rape seed on 10% of the land could produce bio-diesel to replace 50–60% of the tractor diesel used on the farm. Increasing grass-clover area to 20% of the land and using half of this yield for biogas production could change the cash crop farm to an etenergy producer, and reduce GHG emissions while reducing the overall output of products only marginally. Increasing grass-clover area would improve the nutrient management on the farm and eliminate dependence on conventional pig slurry if the biogas residues were returned to cash crop fields.

Potential N-losses in three scenarios for conversion to organic farming in a local area of Denmark

Techniques are needed to investigate whether different strategies for conversion to organic farming might help to reduce N-losses. In this study, an N-balance technique was applied in a local area of Denmark; 25% of this area was designated as environmentally sensitive with special interests to protect groundwater quality. Three scenarios, where 25% of the local area was converted to organic farming, were compared to the present situation with conventional farming. The first two scenarios were conversion to organic dairy and pig production, respectively. The third scenario was conversion of the whole area with special interests in clean groundwater to organic farming, self-sufficient in fodder and fertiliser. Scenario 1 resulted in a lower N-surplus on the dairy farms, but the reduction was too small in order to significantly reduce the N-surplus in either the whole local area or within the area with special interests in clean groundwater. Scenario 2 resulted in an analogous result. In Scenario 3, the N-surplus was reduced significantly within the area with special interests in clean groundwater, but not within the whole local area. The N-surplus reduction from conversion to organic farming was divided into an extensification and a management effect. The extensification effect meant that the lower livestock density in the organic scenarios resulted in lower N-surpluses, due to an exponential relationship between livestock density and N-surplus. The management effect was primarily caused by lower net imports of fodder and fertilisers to the organic farms and the following higher self-sufficiency in fodder. In addition, the distribution of animal manure between the organic farms was more uniform than between the conventional farms and because of the exponential relationship between livestock density and N-surplus, this caused a lower average N-loss potential. We conclude that organic farming can help to reduce potential N-losses in environmentally sensitive areas, but only if the conversion is designed with respect to that aim and takes account of the spatial distribution of farm types present.

Spatial soil zinc content distribution from terrain parameters: A GIS-based decision-tree model in Lebanon

Heavy metal contamination has been and continues to be a worldwide phenomenon that has attracted a great deal of attention from governments and regulatory bodies. In this context, our study proposes a regression-tree model to predict the concentration level of zinc in the soils of northern Lebanon (as a case study of Mediterranean landscapes) under a GIS environment. The developed tree-model explained 88% of variance in zinc concentration using pH (100% in relative importance), surroundings of waste areas (90%), proximity to roads (80%), nearness to cities (50%), distance to drainage line (25%), lithology (24%), land cover/use (14%), slope gradient (10%), conductivity (7%), soil type (7%), organic matter (5%), and soil depth (5%). The overall accuracy of the quantitative zinc map produced (at 1:50.000 scale) was estimated to be 78%. The proposed tree model is relatively simple and may also be applied to other areas.