He who sows will reap is an old and well-known saying. But those who do not fertilize will not reap much either. Manure is necessary for grass to grow and the grass will give you yield and protein back.

It is therefore very important to continue fertilizing, even though the prices for fertilizer are extremely high at the moment. This makes it even more important to use fertilization efficiently. But is this really looked at critically in practice? If you have two grassland plots next to each other, there is a very good chance that both plots will receive the same amount of fertilizer. But perhaps one plot has a much higher protein and yield potential than the other. In journals you see this more and more often in the form of red and green colored yield maps.

A first and simple cause for the difference in protein yield can be found in the quality of the sward. An optimal sward contains a lot of perennial ryegrass bred for high yields and top protein levels. The high yield potential ensures that every kilo of fertilizer results in a lot of home-grown protein. However, if the grassland contains low yielding unwanted grasses, this has a direct influence on the yield. In practice, a livestock farmer will not lower his or her fertilizer application because there are more weeds and bad grasses in the plot. While the potential from the crop is already lower, the effect and the associated efficiency of the fertilizer used will then be lower as a result.

DSV Seeds has conducted multi-year research into the differences between grass types/species. The yields and the associated protein yields differences were very interesting. Perennial ryegrass achieved yields of slightly more than 2000 kg of protein per hectare. Undesirable grasses such as Poa Trivialis and Poa annua grass did not exceed about 800 kg/ha in protein yield. Fortunately, it is not the case that a plot only consists of these bad grasses, but these basic numbers do show interesting values through example calculations. Every 10% less perennial ryegrass on your field has an effect of 128 kg less protein yield per hectare. While the full fertilization with high costs has been made for this. Compared to soya with a protein content of 45%, this amounts to an extra purchase of 283 kg of soy. At current prices of €0.5 per kg of soy, this is about €140/ha.

There are many practical examples that show that good grassland management and timely overseeding can ensure that the percentage of perennial ryegrass can easily increase by 20%. The potential extra protein yield is therefore many times higher than the costs for overseeding and better maintenance of your sward. Keep in mind that if you do nothing, the unwanted grasses will not sit still and compete for space with the perennial ryegrass and this will immediately cost you money.


Luuk Maas, DSV