Forage responses to lime and nitrogen fertiliser on land converted from pine forest to dryland pasture in Canterbury

Abstract

A field trial was established to quantify the impacts of lime (0, 2.5, 5 and 10 t/ha) and nitrogen (N) fertiliser (0, 50, 100, 200 and 400 kg N/ha/year) addition on the dry matter (DM) production of a crop sequence of triticale followed by dryland pasture that was established on a site converted from long-established plantation forestry. Results are reported for the first 22 months. The application of lime up to 10 t/ha had no effect on triticale DM production. In the subsequent pasture, the percentage of clover increased from 15% without lime to 25-30% when 5-10 t/ha of lime was applied. Lime application only increased pasture DM production in the last 4 months. Annual pasture DM production increased significantly with increasing levels of N fertiliser application from 5.3 t DM/ha with no N applied to 7.5 t DM/ha at 400 kg N/ha. The observed response to N addition was mainly attributed to the low N status of the soil following conversion, which in turn was compounded by the ongoing decomposition of large quantities of mulched woody debris.