Strip cropping system for sustainable food and energy production

Strip cropping is a strategy for subdividing single fields into strips with different crops in order to gain the same positive effects known from crop rotations. No additional yield was found by using traditional market pricing, however. When including negative and/or positive yield effects in the interfaces between strips more or less the same biomass was produced when dividing the field into strips (6x6m) as compared to growing the same area with 50% annual crop + 50% perennial crop. Especially, the interspecific competitive ability of grass-clover during the initial growth stages reduces the final annual yields signi¬ficantly. So, why bother changing the well-known sole cropping practices? It is believed that the success of this strip cropping system requires inclusion of additional ecosystems functions and service not necessarily pictured using traditional agronomic market pricing based upon weight of pro¬duce. Ecosystem functions like leguminous N2-fixation and the capacity of e.g. perennial grass-clover to act as carbon sinks should gain more attention when addressing climate change mitigation tools within the framework of OA principles and values. Furthermore, the value of subdividing fields into strips to avoid the build up of pathogens and pests, depletion of soil nutrients and to improve soil struc¬ture and fertility by e.g. alternating deep-rooted and shallow-rooted plants needs further research

A sharp-interface model of electrodeposition and ramified growth

We present a sharp-interface model of two-dimensional ramified growth during quasi-steady electrodeposition. Our model differs from previous modeling methods in that it includes the important effects of extended space-charge regions and nonlinear electrode reactions. The model is validated by comparing its behavior in the initial stage with the predictions of a linear stability analysis.Comment: RevTex, 14 pages, 12 eps figure

Concentration polarization, surface currents, and bulk advection in a microchannel

We present a comprehensive analysis of salt transport and overlimiting currents in a microchannel during concentration polarization. We have carried out full numerical simulations of the coupled Poisson-Nernst-Planck-Stokes problem governing the transport and rationalized the behaviour of the system. A remarkable outcome of the investigations is the discovery of strong couplings between bulk advection and the surface current; without a surface current, bulk advection is strongly suppressed. The numerical simulations are supplemented by analytical models valid in the long channel limit as well as in the limit of negligible surface charge. By including the effects of diffusion and advection in the diffuse part of the electric double layers, we extend a recently published analytical model of overlimiting current due to surface conduction.Comment: 15 pages, 11 figures, Revtex 4.

Weed management in grain legumes using an intercropping approach

Grain legumes benefit the farming system via symbiotic N2 fixation and subsequent residue incorporation contributing to soil fertility together with their effect as break-crop in cereal rich rotations. However, grain legumes are weak competitors towards weeds and consequently weeds constitute a major problem. Since the European policies for reducing the negative effects of agricultural plant production on the environment point to reductions in pesticide use (Mortensen et al., 2000), there is a requirement to further develop strategies to reduce weeds. Intercropping involves the simultaneous growing of several plant species in the same field and the cropping strategy is known to involve interspecific interferences increasing the use of plant growth resources in space and time (Ofori and Stern, 1987) improving crop competitive ability towards weeds (Hauggaard-Nielsen et al., 2001). The main objectives of the present study was to determine the effects of grainlegume-cereal intercropping on the weed biomass production as compared to the respective sole crops using successive harvests in a three-year field study

Do motorways shape urban growth? Analysis of growth patterns with micro-level data – before and after road openings in two Danish motorway corridors

The paper is an offspring from the Research project Town, Road and Landscape that aims to assess the effect of the Danish motorway network (specifically the last 20 years) on urban growth and interaction patterns. As one of the main interests of the project is the changing urban form and the changing character of the roadscape, the impact of the motorway is in part analysed with micro level data, spatial statistics and GIS – to allowing mapping of changing development trends in motorway corridors. The paper presents analysis of the impact of motorway openings on urban form in two Danish motorway corridors. The analysis is based on a before and after perspective – where the building activity and its location (building register with address coordinates) after the opening of the motorway is compared to building activity in the years before the construction of the motorway. Preliminary results suggest that the motorway most markedly influences the location of non-residential building activities within the city – in favour of locations near the entrance points to/from the motorway network. The development can be explained in part by municipal planning, which in some instances has opened up the new locations for development far ahead of market demand – and in part by an increasing demand for exposed and accessible sites for business development which still seems to be in its beginning.