The advantages to pasture quality and quantity through the use of red clover in New Zealand farm systems is becoming more recognised. However, the production interactions between nitrogen fertiliser use and its effect on red clover in pastures is not well understood across multiple regions. Within this study we look to quantify the advantages of utilising red clover in hybrid ryegrass systems and show the effects of nitrogen fertiliser on red clover composition within the sward. In 2019, three replicated plot trials were established in the Manawatu, Canterbury and Southland provinces of New Zealand. All sites were managed with a typical cut and carry system for plot trials for 3 years, with dry matter (DM) production, seasonal feed quality and botanical composition measured. The primary treatments of the trials were tetraploid hybrid ryegrass, with and without red clover, with a nitrogen fertiliser treatment (276 kg N/ha/yr) and without overlayed. The trial results showed that adding both legume and fertiliser increased total dry matter production, as well as increasing the nutritional value of the pasture. Compared to straight hybrid ryegrass without fertiliser, when red clover or nitrogen fertiliser was added to the pasture mix/sward separately, total yield over three years increased by 18,147 kg DM/ha & 14,802 kg DM/ha respectively. When both red clover and nitrogen fertiliser were added to the pasture mix/sward, yield was increased by 23,301 kg DM/ha over three years. Fertiliser use and season had a significant effect on the red clover percentage of the pasture. However, even in the nitrogen fertiliser treatments, red clover proportions remained in excess of 15% across spring, summer and autumn. During winter, clover growth was minimal and contributed very little to dry matter production. Overall, the addition of red clover in pasture can significantly increase overall production and potential profitability of a farming system regardless of fertiliser practice. Maintaining fertiliser contributed to a balanced pasture which benefited the autumn-winter production phase.
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