Grass-clover in organic dairy farming
Grass-clover leys are essential for animal welfare, feed supply and soil fertility building on organic dairy farms, The proportion of grass-clover in the crop rotations increases on Danish organic dairy farms and, in combination with a general increase in farm sizes, this leads to high grassland frequencies near the farms. The main reason is that uniform grazing of all cropped land becomes inexpedient due to long distance to the milking facilities. This development has got implications for a number of aspects such as:
- accumulation and loss of nutrients
- loss of productivity and quality in grass-clover mixtures of longer duration
- increasing problems of establishing white clover.
However, the longer duration of grasslands may also provide an opportunity to control nutrient losses due to less frequent grassland cultivation.
The theme of the present project is grass-clover leys as an integrated part of organic dairy farms. The focus is on management strategies with the purpose of overcoming the above-stipulated shortcomings by manipulating grassland frequency, grazing intensity (and nutrient load), species richness, and arable crop sequence following grassland cultivation. The management strategies will be evaluated on the basis of nutrient use efficiency, productivity, feed quality and biodiversity at the field and crop rotation level and in a whole farm economic and environmental perspective. The aim is to propose strategies for a cost-efficient feed production and efficient nutrient utilization in organic dairy production systems.
The research consists of six interrelated work packages (WPs). WP1-2, which are also the primary experimental units, deal with production and nutrient utilization aspects at the crop rotation level. WP3-5 deal with aspects of biodiversity in relation to production and nutrient utilization. Finally, WP6 deals with production, nutrient utilization and economics of whole farming systems.
Specifically, WP1 evaluates different strategies for mixed crop rotation composition and grassland management regarding productivity and environmental impact in a factorial designed field experiment on loamy sand that represents a very wide range of dairy farms from intensive to very extensive. This is done by quantifying grassland performance, nitrogen leaching from grassland and the residual effects and nitrogen leaching following cultivation.
WP2 focus on grazed grassland of longer duration on a coarse sandy soil under private farm conditions. The effect of grazed grassland management on productivity and nitrate leaching is determined and the effect of fertilizer and catch crop use in maize following grassland cultivation is investigated.
WP3 aims at developing multi species grass-clover mixtures, also including herbs, with high persistence and herbage quality through species composition and management. The soil-plant processes leading to an efficient use of multi-species mixtures is the subject of a Ph.D. study including quantification of nitrogen transfer and deposition, nutrient uptake efficiency and competition for individual nutrients in multi species mixtures and related to effects on herbage quality.
WP4 will seek methods to avoid the increasing problems of establishing white clover on near-farm clover rich areas. The growth and the disease carrying by other crops, including legumes, will be investigated on clover fatigue soil.
WP5 studies the influence of earthworm burrows on nitrate-N loss via macropore flow and how this is affected by management practices, such as cattle grazing, and duration of grass-clover leys.
Finally, WP6 evaluates the management strategies and combinations of crop rotations investigated in WP1-3 in a whole farm perspective. This is carried out by optimizing representative whole farm prototypes regarding production, self-sufficiency, farm economics and environmental load and by creating scenarios for organic dairy farms using an economic model.
The aim is that results from this project will help ensuring a production on large organic dairy farms that presents a real alternative to conventional dairy farming by being environmentally attractive, in agreement with the organic principles and economically viable.
Project title
Grass-clover in organic dairy farming - options to reduce costs and improve nutrient utilization (OrgGrass)
Project leader
Jørgen Eriksen, Senior scientist, Faculty of Agricultural Sciences, University of Aarhus, Research Centre Foulum, P.O. Box 50, DK-8830 Tjele. Phone: (+45) 8999 1870. Fax: (+45) 8999 1619. E-mail: Jorgen.eriksen@agrsci.dk
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