ARCHIVE: Fertiliser Manual (RB209)
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Check list for Decision Making


The following checklist provides a convenient framework for making accurate fertiliser decisions.

It is important that individual decisions are made for each field on the farm each year.

Planning grassland management

  1. Plan the stocking rate, and cutting and grazing strategy for the farm, and decide if reliance is to be made on clover as a source of nitrogen. This strategy will need to take account of the Grass Growth Class of the farmland (see page 188). Since the amount of grass growth can be very seasonally dependent, this strategy should be regularly reviewed to adjust for variations in growth as the season progresses.
  2. For each field, plan the amounts and timings of fertiliser applications that are likely to be needed. Remember that nitrogen applications may need to be adjusted depending on the season and recent weather conditions.

Nitrogen

  1. Determine the Soil Nitrogen Supply status of the field (see page 187). Most intensively managed grassland has a high Soil Nitrogen Supply due to dung and urine returned to the soil during grazing or from application of organic manures.
  2. Identify the Grass Growth Class of the field (see page 188).
  3. Use the tables and accompanying notes on pages 191-213 to decide on the nitrogen rate and timing for grazing or cutting. The recommendations give the average nitrogen rates needed to grow grass on the farm for the levels of stocking and feeding intensity specified and according to Grass Growth Class. Little or no nitrogen should be used in most grass/clover systems.
  4. Adjust the recommendation to take account of the available nitrogen supplied from any organic manures applied for that cut or grazing (see page 182 and Section 2).
  5. Review mid-season use of nitrogen depending on actual grass growth and particularly in droughty conditions (see page 189).
  6. Do not apply nitrogen after mid August except where autumn growth is required in grass/clover systems.

Lime, phosphate, potash, magnesium and sulphur

  1. Carry out soil analysis for pH, P, K and Mg every 3-5 years (see page 35). Target values to maintain in continuous grassland or ley/arable systems are:
    Soil pH 6.0 (5.3 on peat soils) for continuous grass
    Soil pH 6.2 (5.6 on peat soils) where an occasional barley crop is grown
    Soil pH 6.0 (5.3 on peat soils) where an occasional wheat or oat crop is grown
    Soil P Index 2
    Soil K 2-
    Soil Mg Index 2
  2. Decide on the strategy for phosphate and potash use. This will be building up, maintaining or running down the soil Index (see pages 38-41). Allow for any surplus or deficit of phosphate or potash from previous manure and fertiliser applications.
  3. If a reasonably accurate yield estimate can be made, consider calculating the amount of phosphate and potash removed in silage or hay crops over the whole season (see page 211 and Appendix 5). This is the amount of these nutrients that must be replaced in order to maintain the soil Index.
  4. Adjust the recommendations to take account of the nutrients in any organic manures applied (see page 182 and Section 2).
  5. Assess the need for sulphur fertiliser. Many silage crops, especially second or later cuts, will benefit from using a sulphate containing fertiliser (see page 212).

All nutrients

  1. Select a compound or straight fertiliser that matches as closely as possible the nutrient requirements calculated above. It is most important to get the rate and timing of nitrogen correct. The exact rate and timing of other nutrients is usually less critical unless the soil Index is low.
  2. Check that the fertiliser spreader or sprayer is in good working order, is serviced annually and is calibrated every spring and whenever fertiliser type changes. Tray-test the spreader annually (see page 49). Check the manure spreader for mechanical condition and calibrate annually.
  3. Keep a clear record of the fertilisers and manures applied.
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