Dry matter production and weed suppression of multi-species pasture mixtures in the first year of growth

Abstract

Perennial ryegrass, plantain, white clover and red clover were grown in monocultures and up to four- species mixtures in Canterbury, New Zealand. The dry matter production and weed content for the first year of growth (2015-2016) were measured. The species were sown based on a simplex mixture design that included all possible combinations of each species. Statistical analysis was performed on the data and a special cubic model was created. Mixtures were found to have greater annual yields and weed suppression than monocultures. All four of the monocultures had similar annual yields (average 16194 kg DM/ha), but they had different weed contents. The red clover and white clover monocultures had higher weed contents (average 15%) than plantain and ryegrass (average 3%). Success in the two-species mixtures was determined by the type of the ingredient species. Two- species mixtures containing a legume and a non-legume had greater annual yields (average 22849 kg DM/ha) than mixtures that contained two legumes or two non-legumes (average 17270 kg DM/ha). The white clover-red clover mixes and the ryegrass-plantain mixes performed similarly and were no better than the best performing monoculture. There was no difference in annual yield of ryegrass or plantain with white clover or red clover. All of the mixtures suppressed weeds well, except for the white clover and red clover two-species mixture, which was the only mixture to have a greater weed content than 5%, with a mean weed content of 18%. There was a yield advantage of including up to three species in a pasture mix, greater species richness than this prodivided no added yield advantages. There was greater weed suppression with two-species mixtures, but more species in the mix had similar weed contents. Evenness of species proportions in the mixtures had no effect on yield or weed supression. Ryegrass, plantain and white clover mixes were sown in alternate rows to test for an effect of species separation. There was found to be no difference in annual yield and weed content between mixtures that had species sown together and species sown apart. The model was used to get an optimum pasture mixture of 30% perennial ryegrass, 30% plantain and 40%, which gave a predicted annual yield of 25974 kg DM/ha.