New sulphur research on grassland

Using lysimeters and a sandy loam soil they found N + S applications increased grass yields by 30%, compared to N only plots over the course of 7 cuts. Treatments received 250kg N/ha, divided over 7 splits. For the two slurry treatments, there was a 24% yield increase by using a N + S fertiliser with slurry compared to N only fertiliser with slurry.

Apparent fertiliser nitrogen recovery (AFNR) which is a measure of how much of the applied N was taken up by the crop was also increased with sulphur applications. N only plots had a AFNR of 39%, compared to 49% for the N + S treatments. For the slurry treatments the addition of mineral S in the fertiliser increased the AFNR by 13%.

The leachate from the treatments amounted to 68% of total rainfall over the 12 month study. Nitrate leaching loses per ha for the N only plots was 48.2kg NO3-N, whilst the N + S treatment was 26 kg NO3-N which was only 2kg greater than the Zero N control treatment. The nitrate leaching losses for the slurry treatments were very surprising. The N + slurry treatment had losses of 82.8kg NO3-N, in contrast to the N + S + slurry treatment which had losses of 33kg NO3-N.

The study concluded that S fertilisation is potentially important for increasing grass yield, N use efficiency and reducing nitrate leaching losses on certain soils.