Effect of annual applications of pelletized dolomitic lime on soil chemical properties and grass productivity

Lime in pelletized form is potentially more convenient for farmers than ground limestone, as it can be applied using conventional fertilizer‐spreading equipment. Pelletized lime is intended to maintain an optimum soil pH when applied annually at a rate of 350 kg lime/ha/yr. Interactions between lime and N fertilizer rate were examined by applying 0, 75, 150, 225 and 300 kg N/ha/yr (as calcium ammonium nitrate) in combination with 0, 175, 350 and 525 kg pelletized dolomitic lime/ha/yr over 3 yr to a permanent grassland sward used for silage production in County Down, Northern Ireland. Equal rates of ground lime, from the same source as the pelletized lime, were applied as a comparison. Effects on soil chemical properties, grass dry matter (DM) yield and herbage nutrient removal were examined. Lime maintained or slightly increased the soil pH, particularly in the top 2.5 cm of the profile, but there was no difference in the performance of pelletized lime compared to ground lime in any of the parameters measured. Lime had no significant effect on grass DM yield or grass quality; however, there was a significant (P < 0.05) reduction in yield at the first cut, particularly in year 2, when the highest lime rate (525 kg lime/ha/yr) was applied in the absence of N fertilizer. The dolomitic nature of the lime (11% Mg) resulted in significant (P < 0.001) increases in soil and herbage magnesium levels, and this could be beneficial for reducing the incidence of grass tetany in grazing animals. The P content of the herbage was also significantly higher in plots receiving lime, which suggests that lime may have enhanced the mineralization of P or stimulated root growth.