Pasture establishment and fertiliser requirements on rehabilitated land after opencast coal mining in New Zealand

Abstract

Existing pasture establishment practices to rehabilitate land after opencast mining in the Waikato coal fields area of New Zealand were examined and compared with an alternative method involving different pasture mixtures, seeding rates, and lime and fertiliser requirements. Pasture establishment and production, botanical composition changes, and plant and soil nutrient status were measured during a 2-year field trial. Highly significant pasture responses were obtained to increased fertiliser inputs. Heavy rates of fertiliser (1000 kg ha -1 superphosphate) were required to raise Olsen P soil levels during the establishment phase whereas half that rate was found to be sufficient for the maintenance phase. An improved seed mixture, containing superior pasture cultivars, established more quickly and out-yielded the existing seed mixture by 58%. The two seed mixtures responded differently to sowing rates; the higher rate increased pasture yields of the improved pasture species but decreased the existing seed mix yields. Liming at 5 t ha -1 significantly increased soil pH and clover content and reduced pasture manganese concentrations from possibly toxic levels. Nitrogen concentrations in pastures were A 98021Received 12 May 1998; accepted 5 October 1998 below optimum throughout the trial and the strategic use of nitrogen fertiliser is recommended as a useful management option.

Efecto de la fertilización fosfatada sobre la composición química de Lotus tenuis y Trifolium repens

“…Resultados obtenidos por Longhurst et al (1999) en pasturas mixtas (leguminosas y gramíneas) son coincidentes con los registrados en este estudio, ya que las concentraciones de N en la pastura se ubicaron por debajo del óptimo (4,5 %) compatible con el crecimiento de la plantas (Cornforth y Sinclair, 1982). Concluyeron que de acuerdo a los resultados del análisis de planta obtenidos, el N y el P fueron los nutrientes que más limitaron la producción de forraje.…”

Integrating Soil Ecological Knowledge into Restoration Management

“…Fertilizers and chemical amendments are commonly used to improve restoration success (Lu et al 1997; Jim 2001; Marrs 2002; Xia 2004). For instance, application of a phosphorus P fertilizer, N fertilizer, and lime, along with appropriate pasture seed mix was needed to effectively reestablish pasture in a New Zealand opencast coal mine reclamation (Longhurst et al 1999). Restoration of former agricultural land, with residually high levels of inorganic nitrogen from long‐term fertilization, may require manipulations to reduce soil fertility that favor the desired plant species adapted to nitrogen‐limited systems (Wilson & Gerry 1995; Paschke et al 2000; Suding et al 2004).…”