Farmland, food, and bioenergy crops need not compete for land

The need to mitigate the effects of climate change has resulted in some governments setting mandates to attain targets for bioenergy production. Recently, there has been concern that the large-scale use of first-generation biofuel feedstocks may result in ‘food displacement.’ New second-generation bioenergy crops can be produced on poor soil and provide a potential solution to this problem if grown on marginal land that was previously uneconomic for agricultural production. However, consequences of this production method are biodiversity loss and carbon release if previously fallow land is cultivated. Marginal land is also less agriculturally productive, and if profits from biomass plantations exceed those from food production, farmers will grow bioenergy crops on prime agricultural land in order to maximize profit. Alternative approaches include utilizing mixtures of native grassland perennials grown on agriculturally degraded lands for bioenergy production and producing biodiesel from microalgae. In New Zealand, research is being conducted on the benefits of integrating bioenergy crops within the present farming system. In this research, the ecosystem services (ES) value of re-instated shelter on irrigated dairy farms is assessed using the novel approach of adopting a bioenergy crop for shelterbelt creation. Together with on-farm ES as well as those external to the farm, ES delivery from shelterbelts—rows of trees or shrubs planted to provide wind protection—potentially improves the profitability of the farming enterprise. By planting a shelterbelt of Miscanthus x giganteus (Mxg), a sterile hybrid bioenergy grass that grows four meters tall, in the northerly corners of fields, we were able to measure the multiple ES advantages generated including shelter for livestock, the growing of a harvestable crop for fodder or renewable fuels, and benefits from creating a new on-farm habitat such as a refuge for beneficial predatory insects and pollinators. Findings show that pastures benefiting from the shelter of the grass have reduced evapotranspiration rates, the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants, resulting in increased yields. In the sheltered field areas, there was a positive influence on soil mineralization rates and beneficial insects. By having bioenergy crops as a valuable co-product of the existing farming system, in this case dairy production, the problem of replacing land used for food production with bioenergy cropping is overcome. The loss of food-productive land is potentially more than compensated for by the value of ES benefits gained if long term sustainability of the farming system and global threats associated with fossil-carbon use are considered.

The prime source of funding for this New Zealand-based Mxg shelterbelt research was provided by Westland Milk Products Ltd, Hokitika, NZ, largely due to the efforts of Chris Pullen, their Environmental Manager. Further funding was provided by DairyNZ and the Bio-Protection Research Centre, Lincoln University.