Ecosystem Services in Agricultural Systems Viewed through a Provisioning Lens.

Soils provide a wide range of ecosystem services including habitat for biodiversity, filtering/detoxification of pollutants, protection of water quality, flood prevention, mitigation of climate change, and provisioning. But to paraphrase George Orwell, “all ecosystem services are equal, but some services are more equal than others”, at least when it comes to agro-ecosystems. Agro-ecosystems are by definition designed and managed by humans to meet requirements for food, fiber, and energy. Hence, provisioning is the lens through which other supporting ecosystem services must be viewed and evaluated. A focus on tradeoffs is essential because all agricultural systems are “disturbed” relative to natural ecosystems they replace, and thus services other than provisioning are generally diminished. In a world soon to house more than 9 billion people with increasing per capita wealth and consumption, it is no longer relevant to study non-provisioning ecosystem services within agro-ecosystems without regard to their role in supporting substantial increases in crop and livestock yields on existing agricultural land, or for production-oriented scientists to study yield-enhancing technologies without regard to environmental impact. There is urgent need for a global research agenda tightly focused on the goal of doubling yields while also substantially increasing water productivity and fertilizer and energy efficiency. It will require interdisciplinary approaches in which environmental scientists work side-by-side with agronomists to understand the chemical, physical, and biological conditions that can support substantial and sustainable increases in yield while also reducing agriculture’s environmental footprint. Yield-adjusted metrics become important yardsticks to measure progress towards this goal because it is easy to reduce negative environmental impacts from agriculture by managing for lower yields. The worst threat to non-provisioning ecosystem services is if the increased demand for food, fiber, and energy is met through expansion of agricultural area, and diversion of increasing quantities of water for irrigation, at the expense of remaining biodiverse and C-rich rain forest, wetlands, and savannahs. Unfortunately, crop yields are not rising fast enough to avoid this scenario such that current rates of agricultural expansion are higher than at any time in history. Turning this tide can only be acheived by talented young scientists with adequate funding resources and a clear mandate to focus on ecological intensification of agriculture.