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. Keywords: land-use conversion, plantation forestry, pasture, lime; nitrogen fertiliser

Yield and botanical composition of pastures sown under rape into an ex- Pinus radiata forest block

“…The sown grasses represented Յ50% of the total DM yield at all harvests. This probably reflects the lack of available nitrogen in the system immediately after the removal of trees and the high wood content, meaning N is immobilised during decomposition due to a high C:N ratio (Condron et al 2007). Typically, cultivated soils will release nitrogen that can result in establishing pastures being grass dominant.…”

“…Stump grinding and soil conditioning procedures were then used to create a seedbed following a winter fallow. Soil tests were taken prior to pasture establishment and are presented in a separate paper (Condron et al 2007). A strip plot experiment (Petersen 1985) was sown on 6/10/2005 with three grass species as the main plot strips and replicated four times giving a total of 12 main plot strips.…”

“…These actions destroy aggregate integrity and create fine soil particles prone to wind erosion. Capital fertiliser inputs of sulphur, phosphorus, trace elements and lime can overcome low fertility levels and the rate of increase is affected by the rate and timing of applications (Condron et al 2007). In Canterbury, forestry plantations were historically sown on marginal land with shallow soils of low water holding capacity.…”

Pasture composition and production from different cropping sequences in dryland pasture converted from Pinus radiata forest

“…This ensures superior woody weed control and high legume abundance. The clover dominant pastures will enhance livestock feeding value and increase nitrogen inputs into the soil, which in turn should promote pasture growth and the decomposition of woody debris (Condron et al 2007).…”