Choosing the moment and the quantity determine, among other things, the quality and yield of the first cut. ‘Fertilize according to the amount you want to harvest,’ says forage specialist Harrald Helmers.
‘In practice, we find that too much is sometimes harvested in relation to what has been fertilized. Or that too little is harvested in relation to what has been fertilized,’ says Harrald.
To make it easier to empty the slurry pit or silo, it is important to mix the slurry well. It is therefore advisable to start this in good time. Helmers: ‘Slurry that has been mixed well also ensures even absorption over the field. This benefits the crop because the fertilizer becomes available sooner as a source of nitrogen for the grass.’
Fertilize as early as possible
Slurry needs time to be converted into a source of nutrition for the grassland. It is therefore advisable to start slurry spreading as early as possible, if the land allows it. Harrald: ‘If you fertilize as soon as the land allows you to do so, it's done. It doesn't matter if there's a period of rain in March and the fertilizer is also immediately available when the soil warms up.’
Slurry can easily be left on the land for a longer (cold) period, because slurry hardly washes away. Once the soil begins to warm up and a certain temperature is reached, the bacteria become active that absorb and convert the fertilizer into nitrogen.
Adding water positively affects the absorption of the slurry. This is best done when the slurry is being discharged through a trailing hose. ‘The slurry is used more efficiently and better through the addition of water. Even when spreading the liquid fraction,’ says Harrald.
NDF digestibility of grass
Grass that is not given enough nitrogen will lignify sooner. This has a negative effect on the NDF digestibility of the crop. The cell content is then not released so well in the dairy cow's rumen. ‘It's therefore very important to fertilize according to what you want to harvest. Coordinate this well.’
Too much fertilization means that too much unusable protein (NPN) becomes available to the dairy cow. These are proteins that the cow cannot use, but which are processed by the rumen bacteria (rumen flora). This is lost energy and room in the rumen. It also negatively affects your protein extraction from your own land and thus your cycle.