Silage improvements can boost sulphur
GrowHow reports that applying the right levels of sulphur across the growing season delivers substantial gains in grass quality and quantity, writes Dave Mitchell.
Sulphur is now widely accepted as one of the big four nutrients along with nitrogen, phosphate and potash, but many grassland farmers could benefit from paying closer attention to their applications.
The majority of grassland gets plenty of slurry which contains sulphur but it is mostly in the organic form and unavailable to the grass. This means that the only way to guarantee enough sulphur is through applications of mineral fertiliser. At the recent Livestock event, sulphur was clearly the subject of greatest concern with many farmers seeking advice on which product is best to use for their situation. GrowHow is committed to doing on-farm trials to check how products perform in real-life situations. This year, results from trials in the Midlands and Southwest in 2015 have shown the value of sulphur.
Two trials in Somerset gave a good illustration of how sulphur improves crude protein levels in the crop. One trial took place near Shepton Mallet, the other near Wellington – although they are little further south, conditions on these farms were similar to what you see in Wales and the Midlands.
On both farms, using SingleTop instead of straight Nitram gave crude protein levels about 1.5 per cent to two per cent higher. Although this might seem like a relatively modest jump, when translated across all the silage produced on farm it can mean improvements in use of home-grown feed. For example, in a dairy system, if improvements in silage allow an extra intake of 1kg DM (11 ME) per cow per day, then milk output could increase by two litres; 48p per cow. Looking at it another way, it is a saving of 0.88kg in concentrate fed or 16p less spent on every cow. Of course, higher dry matter intake means that more forage is needed to meet the livestock's demands. Fortunately, sulphur has a beneficial effect on yield as well as quality.
Results from trials show between 10 per cent to 60 per cent yield increases from sulphur application.
On one farm in Leicestershire, where soil P and K indexes were at the target of two, GrowHow looked at the effect on yield of using straight Nitram or MultiCut Sulphur (23-4-13 +7 SO3). The grass which received MultiCut Sulphur out-yielded that which got just Nitram.
In one field the difference was 0.4 t DM/ha in the other it was a huge 1.8t DM/ha.
Increases in dry matter yields of this size can substitute for significant amount of compound feed that will provide real savings. Using sulphur to increase yield by 0.5t DM/ha provides a benefit after cost of £50 to £75/ha if the extra energy is used to replace bought-in concentrate.
* Dave Mitchell is fertiliser manager for Wynnstay
