In the past, when dairy income has been tight, withholding autumn fertiliser has been seen as a valid means of containing costs.
But is it a sound option? Farmers that spent less on feed last spring, without reducing animal numbers, are reporting fewer cows in-calf than usual. Empty cows are a real extra cost that will impact negatively on next season’s production.
Most dairy farms now have little wriggle room when it comes to feed availability. The requirement for maximum production has to be found from somewhere. When budgets are already tight, risking being short of spring feed by withholding fertiliser this autumn could be very costly.
If fertiliser inputs this autumn are reduced, what is the priority component needed? On many properties phosphorus inputs, particularly last season, were significantly above maintenance. Potassium availability in autumn after a dry summer is nearly always adequate for strong winter and early season growth, as is sulphur.
A low cost option this autumn, that ticks a number of important boxes for the next six months, is Golden Bay dolomite, a relatively inexpensive natural product containing both calcium and magnesium.
Properties where dolomite is applied regularly in autumn have few, if any, severe cases of calcium/magnesium related metabolic disorders in spring,
Any clinical cases that do eventuate are not severe, and rapidly respond to a single treatment. Which means that valuable time is not lost in spring treating cows that are down for a lengthy period. When cows get back to their feet quickly little muscle damage occurs, and the impact on the season’s milk production is minimised.
In our twenty-five years of providing dolomite for intensive dairy, there has never been any doubt or criticism of its effectiveness. Trial work at Massey University’s Fertiliser and Lime Research Centre showed that dolomite effectively lifted plant magnesium levels soon after application, and remained effective for at least 17 months.
Magnesium is also a carrier for phosphorus, helping ensure sufficient phosphorus for maximum pasture production and energy until at least late spring. The typical dolomite application rate to intensive dairy properties is 220kg/ha, which effectively applies 25kg of magnesium per hectare.
At this rate a typical truck and trailer load of around 28 tonnes provides sufficient magnesium for 130ha, and with regular annual applications a steady increase in soil test magnesium levels can be expected.
The outstanding animal health and overall performance benefits provided by dolomite is due in large part to its ability to improve physical soil structures. As a highly effective soil conditioner it helps with the drainage of excess water in winter, and has the same liming effect as high quality limestone.
Autumn is the ideal time to apply dolomite, as sufficient time is available for plant magnesium levels to lift for a largely trouble free-calving, and ensure high levels of per cow production throughout the remainder of spring.