Reseeding of a Long‐Term Permanent Grassland With a Multi‐Species Sward: 3. Mineral Concentration Effects

Grasslands provide essential minerals to support livestock farming systems. Grassland plants provide minerals cost‐effectively and help prevent nutrient‐related diseases. The aim of this study was to investigate the effects of nutrient inputs and sward type on the mineral concentration of herbage. A long‐term experiment with a permanent grassland (PG) sward was partially reseeded (i.e., half the plots) as a multi‐species sward (MSS) to enable a comparison to PG. The PG and MSS plots were cut three times each year to represent a typical silage system. Nutrient treatments had a increasing effect on the mineral concentrations, apart from the concentration of Fe. Slurry rate increased the concentration of P, K, Cu and Zn, but a decreasing effect on the concentration of Ca. Slurry type effects varied in nature. Pig slurry increased the concentration of P, Na and Zn compared to the cow slurry, but the concentration of K and S was higher for cow than pig slurry. There was a lack of consistent sward type effect; however, the concentration of Ca, Na and Zn was higher for MSS compared to the PG sward. For all minerals there were large and significant year effects, although for macrominerals the highest concentration was in the autumn harvest cut. Thus, variability in mineral offtake was climate‐dependent and is an ongoing challenge for grassland management. The MSS sward herbage had a decreased Tetany Index value compared to PG swards, which is positive for livestock health. These results identify opportunities to effect mineral composition via simple management practices which can improve the sustainability of grasslands.