Effect of modern red clover & nitrogen fertiliser on yield, quality and botanical composition of a hybrid ryegrass sward

Abstract

The advantages to pasture quality and quantity using red clover in New Zealand farm systems is becoming more recognised. The performance of tetraploid hybrid ryegrass, with and without red clover, and with and without nitrogen fertiliser (276 kg N/ha/annum) was compared with a pure red clover stand in three replicated plot experiments, established in 2019 in the Manawatu, Canterbury and Southland provinces of New Zealand. This paper presents the combined multi-site analysis of treatment, season, and year, comparing dry matter (DM) production, composition and feed quality under a cutting regime for 3 years. Adding both red clover and fertiliser to hybrid ryegrass increased total dry matter production, metabolizable energy and crude protein concentration of the pasture. Hybrid ryegrass without fertiliser yielded 24,660 kg DM/ha over three years, while the addition of red clover or nitrogen fertiliser separately increased total yield (p<0.001) by 18,180 and 14,850 kg DM/ha respectively. When combined, yield was increased (p<0.001) by 23,340 kg DM/ha. Fertiliser use and season had a significant effect (p<0.001) on the red clover percentage of the pasture. While fertiliser
use decreased the percentage contribution of the clover to total yield, total yield was increased from additional grass growth particularly in late spring and summer and additional red clover growth in summer. The addition of red clover in pasture significantly increased overall and seasonal production regardless of fertiliser practice. Maintaining fertiliser contributed to a balanced feed curve with high total production and benefiting the autumn-winter production phase.