Brought to you by Limagrain
'Rotate grass clover with arable land in 3 years'
The abolition of the derogation – and the designation of the NV areas on top of that – reduces the nitrogen usage space. This can be partly compensated by using nitrogen-fixing crops such as clover. Good results are achieved in a three-year rotation of grass-clover with arable land, says DLO researcher Koos Verloop.
The biggest challenge under the new regulations is the financial picture, according to Verloop. "Technically, the nitrogen supply by means of artificial fertilizer can still be kept at a reasonable level. But the catch is in the high cost of removing animal manure, and having to buy expensive artificial fertilizer in return."
Clover as an alternative
That is why the use of clover is the most chosen solution. But maintaining the clover share in permanent grassland is difficult. "You often see colorful patterns where clover occurs unevenly in the grassland, instead of a nice even distribution through the plot." Weeding also occurs sooner at lower N fertilization levels, certainly in combination with drought, and clover is sensitive to the agents used to combat weeds such as dandelion.
Always a new start
To counter this, you can opt for a rotation of three-year grass clover in combination with arable land, Verloop advises. The clover share is massive, especially in the second and third year. "In temporary grassland, you always make a new start with the clover; the share remains at a good level and you have less weeding."
The next crop - usually corn - also benefits from the nitrogen built up in the soil. Moreover, clover thrives best with a not too high amount of active nitrogen, preferably less than 200 kilos per hectare. That also fits well after arable land that has been impoverished after corn cultivation, for example, he indicates. "Restraint with the use of artificial fertilizer nitrogen is conducive to nitrogen fixation with clover. If this works well, you can consider it a financially attractive form of fertilization."
Need potassium
Grass clover cultivation works well on sandy soils, loam and possibly clay soil. It is more difficult on peat soil, because the high acidity is in the way of clover. What is important when growing grass clover is that clover needs potassium. This makes it even more important to optimally use the animal manure that you are still allowed to use, according to Verloop. "And if necessary, supplement potassium with artificial fertilizer."
Clover supplies 45 kilos of N per hectare
The yield of clover in grassland is usually determined as a weight percentage of the total dry matter yield and is usually estimated to be half of the coverage. So: a grass-clover plot with 30% clover coverage has a 15% share in the annual yield of grass-clover as a whole. Suppose the annual yield is 10 tons of dry matter per hectare, then the clover yield is 15% of that – 1,5 tons per hectare. The expected nitrogen fixation is then 1,5 times 30 kilos (the amount of N that is fixed per ton of dry matter of clover according to Verloop), or 45 kilos per hectare.
Limagrain offers various options for composing a grass-clover meadow. Havera 5 is a ready-made mixture. But mixing clover into a mono-mixture grass is also an option. In that case, preferably choose a mix of white and red clover (Havera clover mix). White clover can be seen as English ryegrass, which does well in grazing and mowing. Red clover has a higher production, starts earlier in the spring (initial development) and matches well with mowing. Adding white and/or red clover separately is also possible. For temporary, short-term grassland (up to three years) there is the special rotation mixture Havera 2.
