N fertiliser advice for cut swards
Rates of fertiliser N are shown as kg/ha
|Table 1:- Nitrogen Rates for Cut Swards|
|Crop||N application rate (kg/ha)|
|Silage (1st Cut)||100|
|Silage (2nd or subsequent cuts)||80|
|Hay||65 - 80|
Rates shown above refer to application of available N. Chemical fertilizer rates should be calculated by deducting the available N contained in organic fertilizer applications from the rates shown in the table above.
P and K for silage
Phosphorus (P) and Potassium (K) for silage
Table 2:- P and K requirements (kg/ha) for grass silage. (Rates shown are total requirements, before deductions for organic fertilisers).
|Soil Index||Cut Once||2nd and subsequent cuts|
|P (kg/ha)||K (kg/ha)||P (kg/ha)||K (kg/ha)|
- 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.
Fertiliser Values for Cattle Slurry
Cattle slurry is a valuable source of N, P & K and should be applied to silage fields to ensure the return of P and K. This will help maintain P and K levels for optimum production in the farms silage area. Cattle slurry has the correct P : K ratio for fertilising the grass silage crop. Table 4 below shows the N, P & K value of slurry and the effect of LESS on slurry N recovery. 33m3/ha of good quality cattle (6% DM) will slurry sufficient P & K to grow a crop of 1st cut silage on Index 3 P & K soils. On Index1 & 2 soils reduce P and K availability by 50% and 10%, respectively. On Index 1 & 2 soils use a high N low P & K fertiliser blend (27’s or 24’s) to complement the P & K in cattle slurry to ensure the crop has sufficient levels. It is also important to take account of any P & K applied to silage fields prior to closing for silage for example silage ground maybe grazed and may have received an application for example of 18-6-12 in March which will help feed the current silage crop. See table 5 for suggested fertiliser programmes with and without slurry.
Suggested Fertiliser (N, P & K) Programme for 1st Cut Grass Silage (Fertiliser Only)
Table 3. N, P & K requirements for 1st Cut Grass Silage (5t/ha DM) & suggested fertiliser programmes
*The P and K rates shown can be supplied by either slurry or fertiliser