ARCHIVE: Fertiliser Manual (RB209)
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Differences between 7th and 8th editions of grasslands chapters of (RB209)

  • The nitrogen recommendations are based on a new analysis of existing national multi-site nitrogen response data for UK grassland.
  • The overall approach is no longer totally based on the Nopt for grass growth. The new version is based on the need to supply sufficient home grown forage for particular animal production systems (dairy, beef and sheep) at different levels of intensity of production, stocking rate, and concentrates use.
  • This a farm systems based approach.
  • The new recommendations enable farmers who may be operating at widely different stocking rates and feeding different levels of concentrates to obtain relevant recommendations for whole season total nitrogen requirement.
  • Nitrogen requirements have been calculated using commonly accepted values of daily liveweight gain, forage intake and feed energy conversion to milk, proportions of available land devoted to cutting and grazing and efficiencies with which home-grown forage can be utilised under the two harvesting regimes (cut and grazed grass).
  • Whole season nitrogen requirements are provided in groups of tables for each of the main livestock enterprises, dairy, beef and sheep. The first categorisation in each livestock section is by Grass Growth Class, where recommendations are provided for both cut and grazed grass.
  • The recommendation tables indicate how it is possible to decrease total nitrogen requirements the better the Grass Growth Class in order to produce the target amount of home grown forage, as nitrogen is used more efficiently. In other words, the better the Grass Growth Class, the greater the efficiency of nitrogen use and a reduced risk of nitrogen losses to the environment. Conversely, the poorer the Grass Growth Class the higher the nitrogen requirement (assuming no other limiting factors, such as shortage of phosphate, potash and sulphur supply). This reflects the need to support a target economic level of animal production rather than maximum yield of forage.
  • There is improved guidance on nitrogen contribution from clover, based on photographic recognition of percentage cover in the sward.
  • The intervals between the indices for phosphate and potash have been increased to 30 kg/ha (from 25 kg/ha) to bring the rationale in line with arable soils.
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