Over-Drilling New Zealand Tussock Rangeland with or without a Previous Legume Phase

A nineteen year trial at Lake Tekapo compared the longer term trends of over-drilling legume and grasses into either previous undeveloped tussock country or following a previous legume phase. Tall oat grass (from summer sowing) and cocksfoot (from spring sowing) were the most successful of the sown grasses. They remained a low proportion of the swards but greater with prior herbicide treatment, sown with an experimental drill giving partial cultivation and with starter nitrogen fertiliser. Perennial lupin became the main species in the previous undeveloped block and was increasing in the previous developed block. The analysis stage considered the inclusion of covariates for contoured location responses as well as treatment effects in such multi-plot field trials on uneven ground.