Dairy notes July 2007
Forage Stocks
The temporary break in the good weather in May has produced 2 distinct groups of producers:
- Those who took a very heavy cut and are now wondering where to store second cut. For some an option may be to combine for grain, wheat crops originally planned for cutting as whole-crop but for most big bale silage will be the option.
- Those who cut lighter crops early to ensure good quality. Some may have to rent extra 2nd cut land from producers with a heavy first cut if not they will have to plan a third cut to ensure sufficient forage stocks for the coming winter.
Big bale silage production
Under SSAFO regulations, bales can be stored on a hardcore area provided they are at least 10 metres from a drain. Store the bales on a level, smooth, hard surface with good access. The surface should be sufficiently firm to allow easy access to the bales in both winter and summer.
Recent research carried out at the Institute of Grassland and Environmental Research (IGER), Aberystyth has shown that applying 6 layers of plastic wrap to a bale instead of the normal 4 will increase the feeding value of the silage. For an extra 70p spent on wrap the 0.45 litres/ day increase in milk yield/cow will produce an extra return of £2/bale.
Planning Third Cut Silage
Second cut silage will soon be in full swing, so for those people who need to take a 3rd cut, it will soon be time to plan
- What area to cut – Measure up silage stocks once harvest is complete (allow for normal settling) to see what forage is in store - compare this with likely winter demand:
Table 1: Conversion factors to convert silage volume to tonnes of silage
| Silage dry matter content % |
Conversion - Tonnes of silage/cubic metre |
|---|---|
| 20 | Multiply by 0.77 |
| 25 | Multiply by 0.68 |
| 30 | Multiply by 0.60 |
Worked example - Silo measures 28 metres long x 10 metres wide x 2.7 metres deep = 756 cu.metres. To convert to fresh weight for a 25% DM silage then multiply 756 m3 x 0.68 = 514 tonnes of fresh silage.
Table 2: Estimated monthly feed requirement of stock
(Assuming silage is 25% dry matter)
| Silage (tonnes/month) | |
|---|---|
| Dairy cow in milk | 1.4 |
| 250-350 KG heifer | 0.6 |
| 350-400 KG heifer | 0.9 |
- What fertilisers to apply? Soil fertility and availability of slurry will have a major influence on choice. 80 KGs. nitrogen (N)/hectare (64 units/acre) is the normal for 3rd cut but phosphate (P) and potash (K) requirements will depend on soil reserves. Table 3 indicates the total P & K requirements for 3rd cut, depending on soil analysis. As Sulphur (S) deficiency is now common in 3rd cuts, it is recommended to also apply at least 25KG S/hectare in the fertiliser.
Table 3 – P & K Recommendations for 3rd cut
| 0 | 1 | 2 | 3 | >3 | |
|---|---|---|---|---|---|
| P KG/ha | 15 | 15 | 15 | 0 | 0 |
| K KG/ha | 80 | 60 | 40 | 20 | 0 |
Allowance has to be made for the N, P & K content of any slurry applied before deciding what fertiliser needs to be applied. For example a field with a typical soil analysis of P index 2 and K index 2 requires 80 KGs. N : 15 KGs. P :
40KGs. K /hectare (64 units N: 12 units P: 32 units K/acre).
If 17,000 litres of cow slurry/hectare (1,500gallon/acre) is applied, the nutrients available for grass growth will be 10 KG N : 20KG P : 48 KG K. Slurry will meet all crops P & K requirements, but an additional 70 KG N will have to be applied as fertiliser e.g. 5 bags 27%N +S /ha (2 bags/acre). If slurry is not available to treat this area, apply 6 bags/hectare (2.4 bags/acre) of a high potash compound.
