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Sheep

N fertiliser advice sheep grazing

Guideline rates for N applications on sheep pasture with normal to low clover content for a range of stocking rates. The suggested timetable applies to ewes with high productivity assuming that no concentrates are offered at pasture. N timetable is for early to mid-March lambing, but depends on several factors including overall farm system, soil, climatic conditions, clover content etc. The N requirements for sheep grazing are generally lower than for dairy cows or cattle.

This is because:

  1. Less silage is required for sheep than for cattle due to the shorter in-wintering period.
  2. Sheep recycle dung/urine more uniformly to pasture and hence there is less herbage waste around dung-pats and, consequently, more efficient herbage utilisation (more uniform post-grazing height and less high grass left ungrazed).
  3. There is a better match between feed demand and herbage growth because feed demand is highest from lambing to weaning (March to early July). It decreases post weaning as lambs are drafted for sale and ewes can be restricted to maintenance feeding.
  4. Clover survival can be encouraged by rotational grazing rather than continuous sheep grazing as sheep preferentially graze clover plants.
Suggested dates and rates for chemical fertiliser N applications (kg/ha) for a well managed sheep grazing system (mid-March lambing; no concentrates offered at pasture) with low to normal clover content1
Typical N application date10 ewes/ha
(130 kg/ha N)
12.5 ewes/ha
(163 kg/ha N)
15 ewes/ ha
(195 kg/ha N)
Late Jan/ early Feb2 33 40 51
Late March/ early April (after 1st grazing) 40 51 68
Late May/ early June - 14 17
Late August 17 25 33
After Silage - 15 20
Total 90 145 189

¹ For a high clover sward, only early application of about 35 kg/ha is necessary(depending on ewe productivity and stocking rate)

² The date of first application will depend on the lambing date. In mild areas, N may be applied from mid-January to early February. For all applications of chemical or organic N fertilisers, the periods during which application is prohibited within SI 31of 2014 must be observed.

*Notes

Nitrogen (N) requirements for pasture

  • There is no reliable soil test currently available for N. Therefore, there is no soil Index system for N in grassland.
  • Recommendations are based on average soil fertility levels.
  • Total N application and on the farm and time of application must be compliant with nitrates regulations.
  • Matching nitrogen fertiliser use to stocking density on the farm at different times of the year avoids excessive use.
  • Applying nitrogen fertiliser ‘little and often’ during the growing season gives most efficient response in terms of grass growth.

P advice for sheep grazed swards**

Simplified P requirements (kg/ha) of grazed swards on sheep farms. (Rates shown are total P requirements, before deductions for concentrate feeds or organic fertilisers).

Grazed Swards
Soil P IndexFarm Stocking Rate (kg/ha Org N)
< 100101 -130131- 170>171
1 24 27 30 33
2 14 7 20 23
3 4 7 10 13
4 0 0 0 0
(kg/ha * 0.8 =units/ac)

Note

  • Rates shown must be deducted to account for P fed to livestock in concentrate feeds.
  • To account for P in concentrate feeds, use either actual P content in the feeds used if available, or alternatively, use a default value of 5 kg of P per tonne of concentrate feed.

K advice for sheep grazed swards**

Simplified K requirements (kg/ha) of grazed swards on dairy farms. (Rates shown are total K requirements, before deductions for organic fertilisers).

Grazed Swards
Soil K IndexStocking Rate (kg/ha Org N)
< 100101 -130131- 170>171
1 65 70 75 80
2 35 40 45 50
3 5 10 15 20
4 0 0 0 0
(kg/ha * 0.8 =units/ac)

(kg/ha * 0.8 = units/ac)

 

*The P and K rates shown can be supplied by either slurry or fertiliser

 

Suggested Fertiliser ( N, P& K) Programmes

N, P & K recommendations for sheep grazing stocked at 130 to 170kg Org N/ha
(10 -13 ewes/ha)
N Advice
kg/ha
Soil P & K
Index
P
kg/ha
K
kg/ha
Fertiliser Programme
(bags/ac)

145

(116 units/ac






(  )= units/ac
1 30 (24) 75 (60) 3 x 18-6-12
2.4 bags 24-2.5-10/ac
2 20 (16) 45 (36) 2.5 bags 18-6-12
1.5 bags CAN/ac
3 10 (8) 15 (12) 3.2 bags 27-2.5-5.0
1.0 bags CAN/ac
4 0 0 4.25 bags CAN/ac

* The above fertilizer programmes have not taken organic manure applications/concentrates fed into account.

 

Sulphur

  • Sulphur (S) is an important nutrient for grassland, and is closely associated with N uptake and efficiency.

  • There is currently no soil test or soil Index system for S.

  • Herbage analysis is the best predictor of S deficiency.

  • Lighter soils with low organic matter contents are generally more prone to S deficiency.

S fertiliser advice

  •   The response to S fertiliser increases as the rate of N fertiliser increases.

  •   On S deficient soils, apply 20 kg/ha per year for grazed swards.

  •  For silage swards on S deficient soils, apply 20 kg/ha of S per cut.

  •   Avoid S application to soils not deficient in S, as excess S may affect the trace element nutrition of plants and animals.

  • S can be applied by using any of a number of straight or compound fertilisers that contain S.