The effect of perennial ryegrass sowing rate and companion grass on the establishment of plantain in mixed pastures

Abstract

Managing the content of plantain in grass-based swards has become an important consideration for farmers intending to use this species to support seasonal forage supply and nitrogen loss mitigation. Changes in companion perennial ryegrass sowing rate and companion grass species were investigated to understand their impact on initial sward yield and the success of plantain establishment in grass-based pastures. In 2021, an agronomic experiment involving
six large-plot trial sites was established in Northland, the Waikato, Manawatū, Canterbury and Southland. This paper reports the sward yield and botanical composition results of the establishment phase, defined as the first two harvests at each site after sowing. Adjusting the diploid perennial ryegrass sowing rate from 8 to 20 kg/ha increased establishment phase yield but reduced mean plantain content across sites from 25% down to 20%. Fast establishing grass species (Italian and Hybrid ryegrass), which achieved the highest early yields, also had the lowest plantain botanical composition at the second harvest (mean across sites 8-13% compared to 21-23% for perennial grasses). Regional and soil type
differences in the success of plantain establishment were evident, with the best results on the Waikato Allophanic soil and the poorest on the Canterbury Pallic soil. Competition during the establishment phase, whether from different grass species or varying sowing rates, can affect plantain percentage. Farmers and advisors need to consider this when establishing multispecies pastures.