Conversion of forestry land back to productive pasture

Abstract

Large areas of pine forests have been logged and the land sold to farmers for converting to pasture in the South Waikato district. This land use change is expected to continue, given the present commodity prices. A trial was conducted on an ex-forest site at Rotorua to assess the feasibility of converting land from forestry to pastoral agriculture. The establishment of pasture (ryegrass and white clover) on an ex-forest site was successful and results after 4 years indicated there were no major problems with the conversion. An application of 4 t lime/ha lifted soil pH levels into the optimum range of 5.8-6.0 and an annual maintenance dressing of 40 kg phosphorus (P) /ha has more than maintained optimum Olsen P levels of 35-45 μg/ml for pasture growth. It is expected however that commercial sites where post-forest soil P levels were lower than on the Rotorua trial site, would require higher capital P fertiliser input. Soil fauna surveys indicated a recolonisation of some soil macro fauna e.g. earthworms, grass grubs and clover root weevil. Recommendations for converting pines to pasture include removal of stumps and forest debris (where practical), vigorous weed control and the application of nutrients such as phosphate that promote pasture production. Keywords: forestry, soil Olsen phosphorus, soil pH, pasture, Pinus radiata