S-index (sulphur)

Sulphur (S) is important for the formation of amino acids and therefore also affects the quality of protein.

Grassland with a good dry matter yield needs an average of 35-45 kg sulphur (85-115 kg SO3) per ha. Tests by the NMI, for example, show that sulphur deficiency results in between 10% and 20% lower yields per ha. Too much sulphur results in too much S in the ration (> 4 g/kg dry matter). This hinders the utilisation of copper (Cu) and selenium (Se) by the livestock, resulting in health problems. Due to lower forage stocks and higher protein prices, a good protein yield per ha is essential for a good financial operating result. However, declining deposition and a limited supply of slurry mean that the supply of sulphur is under pressure.

Insights into the S-supply in relation to the realised grass growth makes it possible to adjust and realise a higher protein efficiency on the farm. This enables you to grow the optimal amount of roughage with high-quality protein, making an excellent raw material for milk.

Eurofins Agro has developed the S-index in order to assess and adjust the level of sulphur fertilisation. The S-index assesses the value of the sulphur supply; it looks at the protein composition, cell walls in relation to the growth stage and the sulphur content.

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More information about the S-index, you can find in the video below: