“It is imperative that we have metrics to verify that sustainable intensification can indeed succeed as a conservation strategy.”
— Jon Fisher
By Marty Downs
A new report developed by Nature Conservancy scientists, Jon Fisher, Timothy Boucher, Samantha Attwood, and Peter Kareiva provides metrics for evaluating the "sustainable intensification" of agriculture.
The world needs to produce 70% more food by the year 2050 to support current trends in population growth and economic development, according to the Food and Agriculture Organization. A strategy known as sustainable intensification, embraced by many conservation scientists, advocates coaxing higher yields from existing agricultural lands while simultaneously reducing impact on the environment as a way to reduce the need for clearing new lands.
This new white paper by Conservancy scientists offers a way to begin testing — on multiple scales — the efficacy of this approach.
Higher crop yields per hectare may reduce the need to clear additional land, but the net effect is not necessarily a reduced environmental impact. The methods used to increase yields can include irrigation, increased fertilization, mechanization, using GMO’s or other improved forms of seed, double-cropping and more.
Approaches such as intensive fertilization raise obvious concerns, but even seemingly benign interventions like improving irrigation efficiency can have counterintuitive outcomes. Farmers whose irrigation is limited by cost or water rights will generally choose to continue to withdraw the same amount of water even if their efficiency is increased. More of the irrigation water is now delivered to the root zone of the crops and transpired (consumed), and less of it returns to streams and groundwater. So less water is “wasted” (applied but not used by the crop), but water consumption actually goes up.
Other common management practices designed primarily to meet environmental objectives (e.g. conservation tillage, or leaving more crop residue on the soil surface) are ineffective in certain situations, highlighting the need to go beyond a one-size-fits-all approach.
In the paper, How Do We Know an Agricultural System is Sustainable?, Nature Conservancy scientists call on the conservation and agricultural communities to look beyond the easy answers and develop sustainability metrics that reflect the outcomes of agriculture as opposed to the practices of agriculture.
Jon Fisher, lead author of the study, says “It is imperative that we have metrics to verify that sustainable intensification can indeed succeed as a conservation strategy.”
The paper proposes a measures framework that can be used from the global scale all the way down to the plot level and relies heavily on data that can be gathered from existing data sources, satellites or aerial surveys. The authors aim to identify outcomes that are important for sustainability and for which data is reasonably accessible. They propose:
- Soil health measured in terms of soil erosion and soil organic carbon;
- Fresh water consumption and quality;
- Landscape degradation measured by habitat conversion, fragmentation, and composition;
- Biodiversity measured in terms of species richness and abundance for both birds and amphibians.
The paper lays out the reasoning behind each metric, as well as existing data sources and potential future sources of data. A concluding section outlines some next steps for obtaining the needed data, as well as future studies to fill in critical gaps in our understanding of agricultural sustainability.
The authors envision this document as a useful step forward in the conversation about sustainable agriculture rather than a simple solution to a complex issue. There are several limitations and gaps to this approach, primarily the fact that agronomic variables such as yield have not been integrated into the measurement framework. Absent this kind of an integrated framework, we will not be able to determine whether or not an agricultural landscape is truly sustainable in the sense of meeting the global demand for food over long periods of time without requiring continued agricultural expansion or other negative environmental impacts.
For more information about these limitations, please read this critique of the paper from David Cleary (TNC's director of global agriculture). The authors also welcome additional comments and feedback on the proposed measures, data sources, and approaches to email@example.com.
Marty Downs is associate director of science communications with the Nature Conservancy