8 research outputs found
Comparative analysis of conventional and organic farming systems: Nitrogen surpluses and nitrogen losses
Nutrient management is a key factor for both economic viability and environmental performance of farming systems. On 32 representative conventional and organic farms in Northern Germany, nutrient management was analyzed in the interdisciplinary monitoring project “COMPASS”. Organic farms had significantly lower nitrogen (N) surpluses compared with conventional farms. The majority of organic farms had very low or even negative N surpluses, indicating insufficient N supply in the cropping system. Nitrogen leaching, however, was too high in many cases on both conventional and organic farms. Strategies for a more targeted nutrient supply in organic farming need to be developed and implemented
Impact of organic agriculture on diversity and abundance of farmland birds in an arable landscape with hedges
A comparative study of breeding bird communities of organically and conventionally cultivated arable fields was carried out in northern Germany in 2005. The research was conducted on 40 pairs of fields (conventional/organic), which were selected with regard to similar field sizes and comparable boundary structures (particularly presence of hedges). Bird communities were solely dominated by the skylark Alauda arvensis L., which was the only frequent species on the tested pairs of fields. Diversity of farmland birds (number of species, Shannon-Index) was not affected by type of management. However, the abundance of skylarks (territories/10 ha) was significantly higher in organic than in conventional fields. As the study will be continued, the one-year findings will be verified with respect to changes of crops in rotations
Beisaat von Zwischenfrüchten als Möglichkeit zur Reduzierung der N-Auswaschung in Wintergetreide?
In a field experiment the potential of mixtures of winter cereals and catch crops to reduce nitrate leaching was investigated. Pure winter wheat showed the highest N-losses (56 kg N ha-1). Compared to a control without a catch crop, winter rye and oilseed radish grown in pure stand or in mixture with a winter cereal reduced nitrate-leaching by 30 to 80 %. However, common vetch had a significant lower potential compared to the tested non-legume catch crops. Further investigations are needed to optimize the system with special regards to the concurrence between cereal and catch crop in autumn and in early spring
Brutplatzqualität unterschiedlich ökologisch bewirtschafteter Ackerfrüchte für die Feldlerche (Alauda arvensis)
Habitat quality of different arable crops for skylarks (Alauda arvensis) was analysed in
a three year field study on 12 organic farms in northern Germany. Grass clover,
spiked spring cereals (barley/spelt/wheat), winter wheat as well as grain legumes
(including mixtures) hold constant abundances of skylarks during the whole breeding
period. In spring oats, winter spelt and winter cereals with awn (barley/rye), however,
skylark densities decreased during the breeding time, which might be explained by
comparatively taller and/or denser vegetation structure of theses crops during
June/July. Crops showed no significant differences in maximum abundances of
skylarks. Concerning possible effects on breeding success, harrowing and/or hoeing
of cereals and grain legumes should be completed as early as possible in spring to
prevent breeding losses. Compared to cereals and grain legumes, the management of
grass clover crops probably resulted in higher breeding losses due to a high intensity
of mowing. While the cutting regime of grass clover used as green manure crops can
be adapted to breeding phenology of skylarks, modification of cutting systems of
forage crops should cause negative effects on quality of forage
Futterqualität, Vorfruchtleistung und Nitratauswaschung von über Winter beweideten Kleegrasbeständen
In comparison to harvesting, grazing is less cost intensive. For economical reasons an
extended duration of grazing period is recommended. Grazing during winter can
cause pasture damages, which is of minor relevance for older grass clover grown on
arable land, which will be ploughed in the following spring. Against this background
yield and forage quality of 3 different legume species, i.e. white clover, red clover and
alfalfa, grown in binary mixtures with two grass species, perennial ryegrass and tall
fescue, respectively, were examined before grazing the third growth in autumn or
winter. Nitrate leaching losses during winter and yield of the following spring wheat
were recorded.
Yield and forage quality of the total sward was not significantly influenced by grass
species while the interaction of legume species and grazing date had a high impact on
yield and quality of the swards. Before grazing in October, swards with white clover
showed lower yields and through lower legume contents also lower crude protein
concentrations compared to swards with alfalfa or red clover. Losses of leave material
led to losses of crude protein concentration in swards with alfalfa or red clover as well
as high losses of energy content in swards with alfalfa, which at the latest grazing date
were significantly lower than in sward with white clover. Mulching the last growth and
autumn grazing led to higher nitrate losses than late winter grazing. After ploughing,
no effect of clover grass management on spring wheat yields was observed. Grazing
in January led to higher grain crude protein contents in spring wheat than autumn
gazing or cutting of the last growth for silage
N-Bilanzen ökologischer und konventioneller Praxisbetriebe in Norddeutsch-land – Ergebnisse aus dem Projekt COMPASS
Nutrient balances are important agri-environmental indicators, which describe the magnitude of potential nutrient losses from farming systems to the environment. In order to analyze production systems at the entire farm scale, nitrogen balances and other agri-environmental indicators were assessed on 32 organic and conventional farms in Northern Germany. On organic farms, nitrogen fixation of legumes was determined on representative fields. Irrespective of the specialization (all-arable farms, dairy farms), nitrogen surpluses were always pronouncedly lower on organic farms compared to conventional farms. Organic farms generally conducted a sustainable nutrient management. However, the total nitrogen supply at the farm scale was not sufficient on many organic arable farms
Beitrag einer termingerecht durchgefĂĽhrten Kainit-DĂĽngung zur Beikrautregulierung in Winterweizen
Due to etching effects on broad leafed weeds, fine ground kainite was used for weed
control before synthetic herbicides have become common practice in conventional
farming. According to the organic standards kainite can be used as potassium
fertiliser. The present study investigates optimal growing stages for application in
organic winter wheat and the range of effectiveness. Kainite was applied at a rate of
800 kg per hectare alternatively at EC 29 and EC 30 under the conditions of morning
dew on days with high sunshine duration. At both growing stages kainite application
reduced the population of hairy vetch, chamomile, cornflower, field pansy, winter rape,
common chickweed and persian speedwell. Application at early growing stages led to
a higher weed reduction
Winter grazing as an alternative to mulching or mowing grass clover swards
Management factors like the type of defoliation and seed mixture influence yield and forage quality of grass clover mixtures. In comparison to harvesting, grazing is less cost intensive. For economical reasons a maximum duration of grazing period is required. Grazing over winter can cause pasture damages. This problem is of minor relevance for grass clover grown on arable land in the last production year, which is ploughed in the following spring. This study compares different grass clover mixtures concerning yield, forage quality and suitability for winter grazing.With this background, tall fescue exerted more significant effect on the dry matter yield than perennial ryegrass. White clover showed significant superiority over all the other tested species, with regard to protein and energy contents. Otherwise, swards with red clover and alfalfa had a significantly higher legume contents and produced higher dry matter and N yields than the other swards. Plots grazed in different periods over winter showed a clear significant loss of grazable matter. The highest loss of dry matter which also was accompanied by a decrease in crude protein and energy content was observed in mixtures with Lucerne. Under mulching systems and early grazing high nitrate losses were measured. After ploughing, the early grazing systems resulted in lower spring wheat yields than grazing in January or cutting systems