Liming acidic soils creates profits, land use options but often more emissions

Context Soil acidity constrains crop production in Australia. The practice of liming can reduce soil acidity but produces greenhouse gas emissions. Aims By examining land use sequences over three decades at a range of locations in Western Australia, this study aims to identify firstly where and when liming might boost farm profits and secondly, what emissions and land use management flexibilities are generated by liming. Methods Bioeconomic simulation modelling is used to identify the gross margins and emissions associated with liming in land use sequences at 14 locations in Western Australia. Three intensities of cropping and three different rotational sequences are considered. The simulations account for price and weather–year variations across a 30-year period of analysis. Key results Liming is profitable at almost all locations and across all rotation sequences examined. Where problematic soil acidity is a feature or is poised to soon become a problem at a location, liming is a profitable ameliorative practice that enables greater diversity in land use. For most situations assessed, liming increases emissions. The exceptions are at locations where liming prevents a switch away from a crop-dominant system, due to soil acidity reducing crop yields, into additional sheep production that increases emissions. Conclusions Liming is profitable in most acidic soil situations and preserves land use flexibility, although additional greenhouse gas emissions are often generated. Implications Liming acidic soils bolsters land use profitability and helps sustain biologically diverse land use sequences, despite often increasing greenhouse gas emissions.