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N fertiliser advice for dairy grazing

Rates and timing of N fertiliser applications for swards grazed by cattle at various stocking rates. Rates of fertiliser N are shown as kg/ha (units/acre in brackets)

N fertiliser advice for dairy grazing
Stocking Rate (kg Org N/ha)Jan
/Feb
MarAprilMayJunJulAugSeptTotal N Rate
≤ 70 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
71 - 90 0 (0) 0 (0) 25 (20) 0 (0) 15 (12) 15 (12) 0 (0) 0 (0) 40 (32)
91 - 110 0 (0) 15 (12) 30 (24) 15 (12) 15 (12) 15 (12) 0 (0) 0 (0) 75 (60)
111 - 130 0 (0) 28 (22) 35 (28) 25 (20) 23 (18) 23 (18) 0 (0) 0 (0) 111 (89)
131 - 140 0 (0) 28 (22) 35 (28) 25 (20) 17 (14) 17 (14) 17 (14) 17 (14) 122 (98)
141 - 150 0 (0) 29 (23) 44(35) 26 (20) 26 (20) 26 (20) 17 (14) 17 (14) 141 (113)
151 - 160 0(0) 29 (23) 44(35) 35 (28) 35 (28) 35 (28) 26 (20) 26 (20) 168 (134)
161 - 170 0 (0) 34 (27) 53(42) 42 (33) 42 (33) 42 (33) 31 (25) 31 (25) 201 (161)
171 - 180 32 (25) 32 (25) 48 (39) 38 (31) 38 (31) 38 (31) 28 (23) 28 (23) 216 (173)
181 - 190 31 (25) 41 (32) 54 (43) 37 (30) 37 (30) 37 (30) 37 (30) 37 (30) 237 (190)
191 - 200 30 (24) 53 (43) 53 (43) 37 (30) 37 (30) 37 (30) 37 (30) 27 (22) 275 (220)
201 - 210 31 (25) 54 (43) 54 (43) 56 (45) 37 (30) 37 (30) 37 (30) 37 (30) 306 (245)
≥ 210 32 (25) 49 (39) 55 (44) 38 (31) 38 (31) 38 (31) 38 (31) 28 (23) 279 (223)

Rates shown above refer to recommended application of available fertiliser. Chemical fertilizer rates should be calculated by deducting the available N contained in organic fertiliser applications from the rates shown in the table above.

Stocking rate is calculated as the total annual nitrogen (kg) excreted by grazing livestock averaged over the net grassland area (grazing and silage area). Stocking rate refers to grassland area only.

Rates shown above refer to grazed swards only, and are not suitable as a guideline value of the N requirement for the entire grassland area. The N requirement for the entire grassland area will depend on the proportions of the area that are grazed, or cut as silage or hay. Lower rates of N should be used where clover is present in the sward. A good clover sward will reduce N requirements.

Only fertilise to the stock-carrying capacity of the soil. This often varies with in the farm.

Chemical or organic fertilisers cannot be applied during periods when application is prohibited by nitrates regulations.

At stocking rates above 210 kg/ha N, N advice is constrained by nitrates regulations.

 

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.

Phosphorus (P) advice for dairy grazed swards*

Simplified P requirements (kg/ha) of grazed swards on dairy 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)
< 130131 -170171- 210>210
1 30 34 39 43
2 20 24 29 33
3 10 14 19 23
4 0 0 0 0
(kg/ha * =units/ac)

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.

Potassium (K) for dairy 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)
< 130131 -170171- 210>210
1 85 90 95 100
2 55 60 65 70
3 25 30 35 40
4 0 0 0 0
(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 Recommendation’s for dairy grazing stocked at 131 to 170kg Org N/ha
N Advice
kg/ha
Soil P & K
Index
P
kg/ha
K
K/ha
Fertiliser Programme
(bags/ac)
201
(161 units/ac)

(  )= units/ac
1 34 (27) 90 (72) 2.7 bags x 10-10-20
1 bag 20-0-15
4.25 bags CAN
2 24 (19) 60 (48) 1.9 bags 10-10-20
5.25 bags CAN
3 14 (11) 30 (24) 1 bags 10-10-20
5.5 bags CAN
4 0 0 5.95 bags CAN

* 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.

Sulphur Def Pic

Fig.1. Areas in Ireland that are possibly deficient in Sulphur

 

S fertilizer 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 fertilizers that contain S.

Beef

N fertiliser advice for grazing

Rates and timing of N fertiliser applications for swards grazed by cattle at various stocking rates. Rates of fertiliser N are shown as kg/ha (units/acre in brackets)

N fertiliser advice for cattle grazing
Stocking Rate (kg Org N/ha)Jan
/Feb
MarAprilMayJunJulAugSeptTotal N Rate
≤ 70 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
71 - 90 0 (0) 0 (0) 25 (20) 0 (0) 15 (12) 15 (12) 0 (0) 0 (0) 40 (32)
91 - 110 0 (0) 15 (12) 30 (24) 15 (12) 15 (12) 15 (12) 0 (0) 0 (0) 75 (60)
111 - 130 0 (0) 28 (22) 35 (28) 25 (20) 23 (18) 0 (0) 111 (89)
131 - 140 0 (0) 28 (22) 35 (28) 25 (20) 17 (14) 17 (14) 122 (98)
141 - 150 0 (0) 29 (23) 44(35) 26 (20) 26 (20) 17 (14) 141 (113)
151- 160 0(0) 29 (23) 44(35) 35 (28) 35 (28) 26 (20) 168 (134)
161 - 170 0 (0) 34 (27) 53(42) 42 (33) 42 (33) 31 (25) 201 (161)
171 - 180 32 (25) 32 (25) 48 (39) 38 (31) 38 (31) 28 (23) 216 (173)
181 - 190 31 (25) 41 (32) 54 (43) 37 (30) 37 (30) 37 (30) 237 (190)
191 - 200 30 (24) 53 (43) 53 (43) 37 (30) 37 (30) 37 (30) 27 (22) 275 (220)
201 - 210 31 (25) 54 (43) 54 (43) 56 (45) 37 (30) 37 (30) 37 (30) 306 (245)
≥ 210 32 (25) 49 (39) 55 (44) 38 (31) 38 (31) 38 (31) 28 (23) 279 (223)

Rates shown above refer to recommended application of available fertiliser. Chemical fertiliser rates should be calculated by deducting the available N contained in organic fertiliser applications from the rates shown in the table above.
Stocking rate is calculated as the total annual nitrogen (kg) excreted by grazing livestock averaged over the net grassland area (grazing and silage area). Stocking rate refers to grassland area only.
Rates shown above refer to grazed swards only, and are not suitable as a guideline value of the N requirement for the entire grassland area. The N requirement for the entire grassland area will depend on the proportions of the area that are grazed, or cut as silage or hay. Lower rates of N should be used where clover is present in the sward. A good clover sward will reduce N requirements.
Only fertilize to the stock-carrying capacity of the soil. This often varies with in the farm.
Chemical or organic fertilisers cannot be applied during periods when application is prohibited by nitrates regulations.
At stocking rates above 210 kg/ha N, N advice is constrained by nitrates regulations.

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 for cattle grazed swards**

Simplified P requirements (kg/ha) of grazed swards on dairy 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)
< 130131 -170171- 210>210
1 27 30 33 36
2 17 20 23 26
3 7 10 13 16
4 0 0 0 0
(kg/ha * 0.8 =units/ac)

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 for cattle 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 Index Stocking Rate (kg/ha Org N)
< 130131 -170171- 210>210
1 70 75 80 85
2 40 45 50 55
3 10 15 20 25
4 0 0 0 0
(kg/ha * 0.8 =units/ac)

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

 

*Deductions for P depending on concentrate feeding  

Concentrate
(t/ha)
Amount of P in concentrates fed to livestock
(This must be deducted from fertiliser P above)
0.5 2.5 (2) 2.5 (2) 2.5 (2) 2.5 (2)
1.0 5 (4) 5 (4) 5 (4) 5 (4)
2.0 10 (8) 10 (8) 10 (8) 10 (8)

 

Suggested Fertiliser (N, P & K) Programmes

N, P & K Recommendation’s for beef grazing stocked at 131 to 170kg Org N/ha
N Advice kg/haSoil P & K IndexP
kg/ha
K
K/ha
Fertiliser Programme
(bags/ac)
201
(161 units/ac)


(  )= units/ac
1 30 (24) 75 (60) 2.4 bags x 10-10-20
5.0 bags CAN
2 20 (16) 45 (36) 1.6 bags 10-10-20
5.3 bags CAN
3 10 (8) 15 (12) 3 bags 27-2.5-5.0
2.95 bags CAN
4 0 0 5.95 bags CAN

 

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.

 

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.

 

 

Grass Silage/Hay

N fertiliser advice for cut swards

Rates of fertiliser N are shown as kg/ha

CropN application rate (kg/ha)
Silage (1st Cut) 125
Silage (2nd orsubsequent cuts) 100
Hay 65 - 80
Rates shown above refer to application of available N. Chemical fertiliser rates should be calculated by deducting the available N contained in organic fertiliser applications from the rates shown in the table above.
If N is applied for early grazing, assume that 20% of this remains available for first cut silage.
An extra 25 kg/ha may be used where necessary for establishment of a good ryegrass sward if pasture is less than 4 years old, provided that the maximum N allowed within the nitrates regulations is complied with.
Where silage fields were grazed rather than cut in the previous year, apply 100 kg/ha for first cut, and 85 kg/ha for second and subsequent cuts.
When more than 2 cuts are taken there is a danger that the allowance in the nitrates regulations will be exceeded.
Less N is advised for hay crops when there is a high risk of crop loss due to high rainfall.

P and K for silage

P and K requirements (kg/ha) of silage. (Rates shown are total requirements, before deductions for organic fertilisers).

Soil IndexCut Once2nd and subsequent cuts
 P (kg/ha)K (kg/ha)P (kg/ha)K (kg/ha)
1 40 175 10 70
2 30 150 10 55
3 20 120 10 35
4 0 0 0 0
  • Silage crops remove more P and K from fields than grazing. Each 1 tonne of grass silage will remove 4kg P and 25kg K per tonne of grass dry matter, respectively.
  • Where swards are being harvested for silage, apply the rates of P and K shown below in addition to the grazing requirements.

Suggested Fertiliser (N, P & K) Programme for 1st Cut Grass Silage

N, P & K Recommendation’s for 1st cut grass silage
N Advice
kg/ha
Soil P & K IndexP
kg/ha
K
K/ha
Fertiliser Programme
(bags/ac)
120
(96 units/ac)

(  )= units/ac
1* 40 (32) 175 (140) 3 bags x 0-7-30
3.5 bags CAN
2* 30 (24) 150 (120) 3 bags x 0-7-30
3.5 bags CAN
3 20 (16) 120 (96) 2.6  bags x 13-6-20
3 bags 20-0-15
4 0 0 3.5 bags CAN
*Apply remaining P & K after 1st cut silage

 

Suggested Fertiliser (N, P & K) Programme for 1st Cut Grass Silage where 33m³/ha (3,000 gallon/ac) of cattle slurry is applied

N, P & K Recommendation’s for 1st cut grass silage adjusted for 33m³/ha (3,000 gal/ac) of cattle slurry (7% DM)
N Advice
kg/ha
Soil P & K IndexP
kg/ha
K
K/ha
Fertiliser Programme
(bags/ac)
120
(96 units/ac)

(  )= units/ac
1* 20 (16) 65 (52) 3bags 24-2.5-10
2* 10 (8) 40 (32) 2bags 24-2.5-10
1.0 bags CAN
3 0 10 (8) 2.8 bags 20-0-15
0 0 2.8 bags CAN
*Apply remaining P & K after 1st cut silage
¹Apply straight N to Index 4 P & K fields