There is general consensus that agriculture can meet the expected future food needs of a growing population, however the grand question is how we achieve this by sustainable means?
A lot has been written, and debated, about the term sustainable intensification – which implies the production of more output from the same area of land whilst reducing negative environmental impacts and improving natural capital and environmental services (Pretty 2008). The main environmental impacts of farming are from conversion of natural habitats to farmland and the loss of agricultural nutrients and agrochemicals to the environment.
The reduction of environmental impacts thus demands that we improve the use-efficiency of nitrogen, phosphorous and water in particular and pursue alternative measures of managing pests through integrated pest management – whilst also maintaining or improving yields. Simple? Well, not really – the achievement of this is one of society’s and science’s grand future challenges. There are two important considerations here – one is the trade-off between economic and environmental goals. The other is that the reduction of the environmental impacts demands a thorough understanding of key biological and ecological processes in agroecosystems – do we possess sufficient knowledge to achieve this?
So what do we know about the effects of efforts to reduce environmental impacts on yields? An important review study (Kremen & Miles, 2012) reviewed the ecological performance of biologically diversified farming systems compared with conventional systems (industrialized) across crop productivity and ecosystem services that contribute as inputs to farming (e.g. soil fertility and pest control). The results demonstrate that there are many nuances to what happens when farms embrace a more diversified production form.
Diversified farming systems have only somewhat reduced mean crop productivity relative to high external input conventional farming systems, but they produce far less environmental and social harm. The study provides substantial evidence to support significant advantages of biologically diversified farming systems for example biodiversity conservation, control of arthropod pests, weeds and diseases, soil quality maintenance, and energy-use efficiency. The authors therefore suggest that it actually is possible to design diversified farming systems that maintain or enhance the provisioning of ecosystem services and thus agroecosystem resilience and sustainability.
Knowledge is key to informed decision making in diversified systems – and further research in for example crop breeding and weed and pest control is imperative to further develop such system types and reduce yield gaps when they occur. Finally, we need to recognize the important role incentives systems play in on farm decision making – after all, it is the farmers who are the principal land managers.
Kremen, C., and A. Miles. 2012. Ecosystem services in biologically diversified versus conventional
farming systems: benefits, externalities, and trade-offs. Ecology and Society 17(4)
Pretty, J. 2008. Agricultural sustainability: concepts, principles and evidence. Philosophical Transactions of the Royal Society B-Biological Sciences, 363, (1491) 447-465 .
Tilman, D., Cassman, K. G., Matson, P. A., Naylor, R., & Polasky, S. (2002). Agricultural sustainability and intensive production practices. Nature,418 (6898), 671-677.