Keywords: Grass growth, nitrogen fertiliser, energy for production, milk and meat production systems.
Grass growth is the basis of milk and meat production systems in temperate regions and nitrogen fertilisation of sown (established) grass swards provides for the optimal balance of herbage growth and quality to meet the demands of livestock production systems. Many factors affect the response of grass to the application of inorganic nitrogen and these are accounted for in current recommendation systems. However, the traditional approach of basing nitrogen application recommendations on response curves that enable calculation of economic response based on fertiliser price does not meet the requirements of the diversity of grassland based systems that exist in milk and meat production. Acknowledging that ‘one size does not fit all’ a new approach is advocated, still based on grass growth response to nitrogen applications, but starting from the objective of providing enough grass energy to meet the demands of the individual production system. Whilst such an approach works well for different system types, further development is needed to ensure that the concept accounts for protein requirements and the energy and protein contributed to the system by farm-grown non-grass crops such as whole-crop wheat and maize silage.
Within any approach to nitrogen fertilisation of grassland, the environmental impact of applications and systems of milk and meat production must be assessed. Different systems have different impacts and whilst loss of nitrogen to the environment should be taken as a characteristic of any livestock system, the effects of different approaches to production are considered.
Dr George Fisher, AHDB DairyCo, Stoneleigh Park, Kenilworth, Warwickshire, CV8 2TL, UK.
Elaine Jewkes, GrowHow UK Ltd, Ince, Chester, Cheshire CH2 4LB, UK.
32 pages, 2 figures, 11 tables, 24 references.