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Environmental and economic value of soil ecosystem services provided by diverse cropping systems

Principal Investigator: Claudia Wagner-Riddle

Research Institution: University of Guelph

Timeline: May 2016 – April 2021

Objectives:

  • Determine how a diverse rotation influences crop nitrogen losses, water conservation, and crop productivity compared to non-diverse conventional rotations.
  • Calculate and compare the profitability and ‘relative advantage’ of diverse vs. conventional cropping systems.

Impacts:

  • The identification of management choices for improving sustainability will enable producers to make informed decisions and they may be more willing to adopt the desired management if they have full information on the environmental and economic consequences of their actions.
  • The results of the research may aid in identifying the most cost-effective policies and programs to support sustainability objectives.
  • The identification of proactive responses against environmental stressors may lead to improving the resiliency of grain farming.

Scientific Summary:

Healthy soils provide essential ecosystem services (e.g., nutrient recycling, carbon sequestration, climate regulation, and water filtration) that sustain plants, animals and humans. The growing trend towards simplifying systems in Ontario and the northern corn-belt (i.e., corn-soy rotations) may risk soil health degradation and resiliency against stress. One strategy thought to improve soil health and ecosystem services is to establish a diverse crop rotation which includes cover crops and/or intercrops in the rotation. To ensure uptake of sustainable agricultural practices in Ontario, the economic and environmental benefits and trade-offs of soil ecosystem services under different management and environmental stressors must be elucidated. Diverse rotations with integrated cover/intercrops might lead to competition for water and nutrients between intercrop and the cash crop, which could negatively impact cash crop yields and profitability, and therefore limit the likelihood of farmers adopting the practice. Two important questions must be answered for farmers: i) will diverse cropping systems actually result in productive and profitable cash crops over time? (ii) what are the trade-offs between environmental and economic benefits of implementing a diverse cropping rotation?

Field research was conducted at the new soil lysimeter site over 2016-2020 to address objective 1. The field work took place using large scale weighing soil lysimeters which allowed us to precisely determine the soil water budget and compare a conventional corn-soybean-soybean rotation with a diversified corn-soybean-wheat rotation that includes use of cover crops. A comprehensive set of soil and plant data was collected, which is available for future analysis on the value of ecosystem services. An economic decision framework was developed which will be used to determine whether a farmer would have been better off (from a profit standpoint) by employing the conventional or the diverse rotation, under the actual weather conditions, for sandy loam or silt loam soil. Weather scenario simulations were also developed and used to examine the economic and environmental trade-offs of conventional vs diverse rotation systems for current and potential future climate conditions. This work can be used to develop proactive responses to ensure agricultural resiliency against climate variability. Specifically, exploring diverse cropping systems and soil health as means of crop insurance could be explored based on this work and the effect reductions in premiums play in incentivizing sustainable management and improving profitability.

Results indicate that a diverse rotation with use of cover crops does not significantly impact yields over a 5-year period compared to a conventional rotation. Winter warming (applied only to diverse rotations) tended to have a trend for lower yields but not significantly. In a separate, but complementary project at the lysimeter site, we have determined that the use of cover crops reduced nitrate leaching by 70% over one of the growing seasons. The private value to farmers of growing winter wheat and cover crops in a rotation with corn and soy, and thus the likelihood of using these practices, is inversely related to the initial level of soil health and directly related to the relative price of wheat, the value placed on future productivity, and the degree of risk aversion. Under average crop prices for the past 7 years, corn-soy (CS) rotations are optimal for fields with moderate to high levels of soil carbon and corn-soy-wheat (CSW) rotations for fields with low soil carbon.

External Funding Partners:

OMAFRA New Directions

We acknowledge the support of the Natural Sciences and Engineering Research Council of Canada (NSERC).

Project Related Publications:

Yanni, S. F., De Laporte, A., Rajsic, P., Wagner-Riddle, C., & Weersink, A. (2021). The environmental and economic efficacy of on-farm beneficial management practices for mitigating soil-related greenhouse gas emissions in Ontario, Canada. Renewable Agriculture and Food Systems, 36(3), 307-320.

Lapierre, J., Machado, P.V.F., Debruyn, Z., Brown, S.E., Jordan, S., Berg, A., Biswas, A., Henry, H.A.L., & Wagner-Riddle, C. (2021) Cover crop mixtures: A powerful strategy to reduce post-harvest surplus of soil nitrate and leaching. Agriculture, Ecosystems & Environment, 325, 107750.

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