62 research outputs found
Potential in mixed swards and breeding of tall fescue (Festuca arundinacea Schreb.)
The incentives of this thesis are some of the challenges that grassland production in Belgium are exposed to. First, more dry summer spells are predicted due to climate change (IPPC, 2007). Second, more grass is cut and conserved due to current trends in dairy production. Tall fescue (Festuca arundinacea Schreb.; Fa) is a forage grass species that is expected to cope with these challenges.
This thesis had three objectives:
1. to study the agronomy of Fa under Belgian conditions;
2. to develop methods that could be used in breeding to overcome the main disadvatages of Fa;
3. to breed an Fa Variety adapted to Belgian circumstances
Welke grasmat voor Brussels Airport?
Op luchthavens is wild (vogels, konijnen) erg ongewenst in het kader van de veiligheid van het vliegverkeer. In de studie beschreven in dit rapport gingen we na welke grassoorten geschikt zijn voor gebruikt op luchthavens, rekening houdend met deze wildproblematiek. De voorkeur van 9 grassoorten of mengsels voor konijnen werd onderzocht in een drie jaar durende veldproef
A method to search for optimal field allocations of transgenic maize in the context of co-existence
Spatially isolating genetically modified (GM) maize fields from non-GM maize
fields is a robust on-farm measure to keep the adventitious presence of GM
material in the harvest of neighboring fields due to cross-fertilizations
below the European labeling threshold of 0.9%. However, the
implementation of mandatory and rigid isolation perimeters can affect the
farmers' freedom of choice to grow GM maize on their fields if neighboring
farmers do not concur with their respective cropping intentions and crop
plans. To minimize the presence of non-GM maize within isolation perimeters
implemented around GM maize fields, a method was developed for optimally
allocating GM maize to a particular set of fields. Using a Geographic
Information System dataset and Monte Carlo analyses, three scenarios were
tested in a maize cultivation area with a low maize share in Flanders
(Belgium). It was assumed that some farmers would act in collaboration by
sharing the allocation of all their arable land for the cultivation of GM
maize. From the large number of possible allocations of GM maize to any
field of the shared pool of arable land, the best field combinations were
selected. Compared to a random allocation of GM maize, the best field
combinations made it possible to reduce spatial co-existence problems, since
at least two times less non-GM maize fields and their corresponding farmers
occurred within the implemented isolation perimeters. In the selected field
sets, the mean field size was always larger than the mean field size of the
common pool of arable land. These preliminary data confirm that the optimal
allocation of GM maize over the landscape might theoretically be a valuable
option to facilitate the implementation of rigid isolation perimeters
imposed by law.
Effect of organic and mineral fertilizers on soil P and C levels, crop yield and P leaching in a long term trial on a silt loam soil
Impact of the quality of organic amendments on size and composition of the weed seed bank
In addition to improving the soil quality, organic amendments of soils may affect weed seed survival, emergence, growth and reproduction. This study evaluated the effects of applications of different qualities of organic amendments on size and composition of the weed seed bank in a field under sequential cropping over 4 years. Fertilisation systems tested included farmyard manure, vegetable fruit and garden waste compost, two types of farm compost differing in carbon:nitrogen (C:N) ratio, cattle slurry and mineral fertiliser. All organically amended plots received equal amounts of C. Crop growth was equalised on all plots by applying supplemental mineral N. Seed bank sampling took place in May 2009 to a depth of 10 cm. The weed seed bank was analysed using the seedling emergence method. Despite equal crop growth in fertilised plots, total seed bank density was lowest in plots amended with compost with low C:N ratio and highest in slurry-amended plots. Observed differences in seed bank densities reflected differences in soil organic carbon content and microbial biomass. At plot level, hard-coated seeds in the seed bank (e.g. Chenopodium spp.) were inversely related to soil microbial activity. Observed differential responses of species to applied fertilisers might be attributed to interspecific differences in resistance against microbial seed degradation. Compost-based fertilisation systems could be sustainable tools for incorporation into integrated weed control strategies aiming at depleting the weed seed bank
Sputter deposited metal layers embedded in composites : from fundamentals to applications
Due to the low heat flux towards the substrate, magnetron sputter deposition offers the possibility to deposit thin films on heat sensitive materials such as fiber-reinforced polymers, also known as composite materials. Passive thermal probe measurements during the sputter deposition of metal layers show indeed that the temperature increase remains well below 25 degrees C for film thicknesses up to 600 nm. The latter thickness threshold is based on the influence of embedded metal films on the adhesion of the composite plies. Films thicker than this threshold deteriorate the mechanical integrity of the composite. The introduction of the uncured composite in the vacuum chamber strongly affects the base pressure by outgassing of impurities from the composite. The impurities affect the film properties as illustrated by their impact on the Seebeck coefficient of sputter deposited thermocouples. The restrictions to embed thin films in composites, as illustrated by both the heat flux measurements, and the study on the influence of impurities, are however not insurmountable. The possibility to use embedded thin films will be briefly demonstrated in different applications such as digital volume image correlation, thermocouples, and de-icing
Effects of synthetic fertilizer and farm compost on soil nematode community in long-term crop rotation plots : a morphological and metabarcoding approach
Soil biodiversity plays a key regulation role in the ecosystem services that underpin regenerative sustainable agriculture. It can be impacted by agricultural management techniques, both positively (through measures such as compost application) and negatively (through, for example, application of synthetic nitrogen). As one of the most numerous members of the soil biota, nematodes are well established as indicators for the soil food web. However, compost application also includes the addition of nematodes present in compost and their subsequent survival in soil is unknown. Nematode communities within the compost applied to soil, and nematode communities in the soil of a multi-year rotational cropping field trial in Melle (Belgium) were studied using morphological and metabarcoding techniques. Compost (C) and nitrogen fertilizer (NF) treated plots were compared. Three replicate plots were investigated for each of the following treatments: C application only; C and NF application; NF only; no C and no NF (control). Plots were sampled six times between 2015-2017, before and after C or NF were added each spring and after crop harvest (except for 2017). NF treatment resulted in a significant decrease of fungal feeding and predatory nematodes, while herbivorous nematodes were positively affected. Remarkably, we did not find compost addition to exert any noticeable effects on the soil nematode community. The morphological and metabarcoding data resulted in different results of the nematode community composition. However, trends and patterns in the two data sets were congruent when observed with NMDS plots and using the nematode maturity index. Metabarcoding of individual compost nematode taxa demonstrated that nematodes originating from compost did not persist in soil
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