Crop rotation limits Canada thistle, but not Couch grass or annual weeds

Direct weed control of annual as well as perennial weeds was necessary to reduce the amount of weeds in organic crop rotation experiments at three locations in Denmark. For Canada thistle, however, the rotation was the most important controlling factor: the rotation with grass-clover had less thistle biomass than the one without

Development of weeds in organic crop rotation experiments

Weeds are a major problem in organic farming. Preventive as well as curative measures must be utilised to manage the weeds and avoid proliferation. Besides direct weed control measures, many different aspects of planning and management in the cropping system affect the proliferation of weeds. However, it has rarely been investigated how the whole system affects weed populations

Productivity and N-leaching in organic dairy grass-arable crop rotations

Increasing size of organic dairy farms makes grazing of all cropped land inexpedient due to long distance to the milking facilities. We investigated nutrient dynamics and feed production in two dairy crop rotations with differences in proportion of grazing and cutting. One six year crop rotation represents close to the farm buildings (barley undersown with grass-clover - 4 years of grass-clover - spring barley/catch crop) and another represents further away (barley undersown with grass-clover, 2 years of grass-clover -barley/catch crop - maize/catch crop - lupin/catch crop). In each of the crop rotations was made five treatments concerning grazing/cutting strategy and manure application. Results shows that herbage production was high in year 1-4 of grass-clover. Nitrate leaching in the crop rotations were highest in grazed and manured 2-4 years old grasslands, but also following maize and lupin considerable losses occurred despite the presence of catch crops. Following grassland cultivation, a barley silage crop undersown with Italian ryegrass reduced leaching to a minimum

Residual effects of cutting and grazing on grass/clover growth

The residual effect of cutting and grazing during the growing season was investigated in the spring and summer growth in an organic crop rotation with 1-4 year-old grass-clover mixtures of white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.) either with or without red clover (Trifolium pratense L.) and with and without slurry. The white clover mixtures had significantly higher yields in spring and summer in swards that were previously grazed compared to previously cut swards, when slurry was applied. The percentage of white clover in spring was considerably reduced by previous grazing and this caused the yield response of slurry application to be highest following grazing. A similar effect on the clover content was not found in the summer growth. With the inclusion of red clover in the sward the effect of previous management on spring yield disappeared. Red clover was very abundant under the cutting regime, while the contents were declining with grazing

Herbs in high producing organic grasslands – effect of management

In many organic grasslands herbs are established due to their expected beneficial properties for nutritive value and biodiversity. However, knowledge about grassland herbs is limited. Three mixtures were therefore established at different grazing/cutting and fertilization managements to examine the growth potential and feeding value. The competitiveness of the different species varied greatly. Chicory, plantain and caraway were competitive in mixtures with traditional grassland species. Lotus and salad burnet were weak competitors and chervil and sainfoin were very weak. The feeding value was also highly variable. Caraway had high digestibility of organic matter, also compared with the traditional grassland species, whereas plantain and salad burnet had lowest digestibility. The management, grazing, cutting, slurry and sward age, affected the proportion of the herb species. The proportion of caraway increased at cutting, slurry application and sward age. The proportion of plantain also increased at cutting but decreased at slurry application and sward age. The proportion of chicory increased with slurry application and decreased with sward age independently of cutting/grazing. The experiment showed that inclusion of herbs in the sward increased the biodiversity, made the herbage mass more diverse without affecting the dry matter yield

Nitrogen management on large organic dairy farms

Large dairy herds need much grassland near the farm. Utilisation and losses of nitrogen in such grass-intensive crop rotations can be controlled by management: In grassland, grazing days or fertiliser input can be reduced, and following grassland cultivation, a barley whole crop for silage undersown with Italian ryegrass can reduce leaching to a minimum

Yield effects of grazing and red clover in white clover/grass mixtures

In white clover/ryegrass mixtures grazing in one year significantly increases the yield in the next, compared to cutting. Red clover is a good supplement to the mixture as it performs well under cutting regime, while white clover takes over during grazing. Overall, inclusion of red clover in the mixture contributes to a more robust sward and increased flexibility in utilizatio

Herbs in grasslands

Ongoing experiments have shown that herbs can constitute a significant proportion of the sward and that management affects the composition. However, the competitive strength and feeding value of the different herb species varied highly

Post-harvest sown catch crops – results from two years of organic field trials

Post-harvest sown catch crops should be sown as early as possible in order to obtain maximum biomass and nutrient uptake in the harvested crop, as biomass production decreased by 2-3.5 percent per day, when time of sowing was postponed throughout August. Furthermore, the winter hardy species included in these experiments had a tendency to yield less than the non-winter hardy catch crops. These experiments imply that early sown catch crops may become a biomass supplement for organic biogas production, provided sufficient yields are obtained and costs for harvest, transportation and storage are adequately low

Ukrudtets udvikling i de økologiske sædskifteforsøg

Kvik og tidsler udviklede sig hurtigt til et problem i de økologiske sædskifter på henholdsvis Jyndevad og Flakkebjerg. Behandlinger mod kvik på Jyndevad havde generelt kun effekt det følgende år. På Flakkebjerg var der tendens til, at sædskifter med kløvergræs kunne begrænse tidslerne