A framework for evaluating ecosystem services provided by cover crops in agroecosystems

Cropping systems that provide ecosystem services beyond crop production are gaining interest from farmers, policy makers and society at large, yet we lack frameworks to evaluate and manage for multiple ecosystem services. Using the example of integrating cover crops into annual crop rotations, we present an assessment framework that: (1) estimates the temporal dynamics of a suite of ecosystem services; (2) illustrates ecosystem multifunctionality using spider plots; and (3) identifies key time points for optimizing ecosystem service benefits and minimizing trade-offs. Using quantitative models and semi-quantitative estimates, we applied the framework to analyze the temporal dynamics of 11 ecosystem services and two economic metrics when cover crops are introduced into a 3-year soybean (Glycine max)-wheat (Triticum aestivum)-corn (Zea mays) rotation in a typical Mid-Atlantic climate. We estimated that cover crops could increase 8 of 11 ecosystem services without negatively influencing crop yields. We demonstrate that when we measure ecosystem services matters and cumulative assessments can be misleading due to the episodic nature of some services and the time sensitivity of management windows. For example, nutrient retention benefits occurred primarily during cover crop growth, weed suppression benefits occurred during cash crop growth through a cover crop legacy effect, and soil carbon benefits accrued slowly over decades. Uncertainties exist in estimating cover crop effects on several services, such as pest dynamics. Trade-offs occurred between cover crop ecosystem benefits, production costs, and management risks. Differences in production costs with and without cover crops varied 3-fold over 10 years, largely due to changes in fertilizer prices, and thus cover crop use will become more economical with increasing fertilizer prices or if modest cost-sharing programs are established. Frameworks such as that presented here provide the means to quantify ecosystem services and facilitate the transition to more multifunctional agricultural systems. (C) 2013 Elsevier Ltd. All rights reserved.