Mowing and leaving the crop spread across the field or raking the grass into a swath immediately. The first method is more common, although mowing and then creating rows is attracting more interest due to changes in grass composition and climate influences. Which of the two mowing methods is used is not that important as long as you follow the correct steps to create a good bale.
The rule of thumb for the optimal moment to mow is just before the crop starts to bloom1. At that moment, the grass has a crude fibre content of 22 to 25% per kg of dry matter. That percentage can increase by 3 to 8 grams a day in the most important growth phase. At a higher fibre content, the digestibility of the organic matter decreases, the FUM is then lower2. For optimal ripeness of the grass, the soil and the plant itself must be as dry as possible. If it’s raining or the grass is still covered by heavy dew, it’s best to delay mowing for a while. If the grass is harvested too wet, silage preservation and palatability for the cow will be compromised. A dry matter content of 35 to 45% is optimal for good preservation and for good forage for the cattle.
Mower higher to reduce impurities in the bale
To encourage the best possible regrowth of the grass, the stubble should be around eight centimetres high after mowing. If there are a lot of irregular patches in the grass, maintaining a stubble height of nine centimetres is an excellent option. Mowing too short is not recommended as this increases the risk of impurities in the bales. A lot of soiling and impurities in the bale also cause a slow pH decline during preservation. In addition, a high crude ash content allows butyric acid to develop, which has a negative impact on the feed value.
Set machines for a good swath
The best way to set the working height of machines used to harvest forage – tedders, rakes and mowers – is on a flat surface4. A level, hard surface in the yard is the ideal place. In this way, you can quickly check if the tines on the tedders and rakes are at the correct working height and if there are no bent tines. On mowers, check the ground pressure, the lifting device and the knives. Set the machine, drive to the field and examine the settings critically again.
Maximising baler performance
The shape and width of the swath are vital to maximise the performance of your baler. The correct swath shape is rectangular5. Remember that the centre of the swath should not be much higher than the sides. This shape ensures the bale chamber is filled better, including in the corners. If all the bale chamber is filled, the majority of air pockets will be removed from the bales, which improves the quality of preservation. An additional advantage is an evenly loaded intake across the entire baler width for maximum capacity.
When the crop is baled, the correct swath width is approximately 150 cm. Depending on the baler pick-up width and field conditions, for example baling on slopes, it may be necessary to form a narrower swath for optimal bale formation.