Dry matter production and botanical composition of three pastures species and their seed mixtures after an autumn sowing using two overall sowing rates

Abstract

Pastoral agriculture in New Zealand is based around the use of white clover and perennial ryegrass. Diploid perennial ryegrass, white clover and plantain were grown in monocultures, two-species mixes and three-species mixes at Lincoln University, Canterbury New Zealand. The dry matter production, botanical composition during two harvests on the 4th of August and the 13th of September 2017 were measured. Ten seed mixes were repeated at two overall sowing rates equivalent to 1000 and 2000 seeds/m2 and at two overall levels of N, 0 and 100 kg N/ha, respectively. A statistical analysis was performed on the data that was obtained from the measurements and a special cubic model was created. This analysis showed that pasture mixes with two species showed better estimated yields than the three-species pasture mixes. Ryegrass and white clover mixes and white clover and plantain mixes showed significant results (P<0.05) when induced as a two -species pasture mix. White clover had the highest weed content of >80% in the monocultures compared with ryegrass and plantain which out competed weeds, only producing a weed content between 5-20%. White clover did not perform as a monoculture with the weeds and soil temperature following an autumn sowing not allowing for good establishment. A three-species pasture mix showed a decrease in production compared with the two-species mixes (P<0.05). Sowing rate had a significant effect on the yield of the first harvest (P=0.003), possibly due to large amounts of germinating seeds that suppress the weed population and result in more herbage especially in mixes containing ryegrass and plantain. The second harvest showed less significance from the sowing rate as pasture mixes that included white clover began to establish better, growing more herbage (P=0.189).There was no statistical effect of the botanical composition of the pastures from the sowing rate. N had an overall effect on yield, having the greatest effect on perennial ryegrass across both harve sts. Overall increasing sowing rate and N levels had an increase in yield benefit but no composition effect.