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Title: Biophysical Constraints and Ecological Compatibilities of Diverse Agroecosystems

Author
item Jaradat, Abdullah
item Riedell, Walter
item GOLDSTEIN, WALTER - Michael Fields Agricultural Institute

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/1/2010
Publication Date: 7/1/2010
Citation: Jaradat, A.A., Riedell, W.E., Goldstein, W. 2010. Biophysical Constraints and Ecological Compatibilities of Diverse Agroecosystems. In: Proceedings of Innovation and Sustainable Development in Agriculture and Food, June 28-July 1, 2010, Montpellier, France. Available: http://www.isda2010.net/var/isda2010/storage/original/application/d720c0904916b402b34871306dac19f0.pdf.

Interpretive Summary: Climate change will disrupt many agro-ecosystem functions, alter their capacity to provide goods and services and render them more susceptible to degradation. Many agro-ecosystems will be less sustainable with a decreased capacity to respond or adapt to climate change unless appropriate mitigation and adaptation strategies are implemented. The diverse subsistence and organic agro-ecosystems in the Fertile Crescent of West Asia and the organic and conventional agro-ecosystem in parts of the northern Corn Belt and northern Great Plains of the US represent contrasting rainfed production systems. Two representative agro-ecosystems were used to identify biophysical constraints, technological changes, and ecological compatibilities under projected climate change. The subsistence agro-ecosystems in the Fertile Crescent lack technological change, rely on low external inputs, and are increasingly marginalized; whereas, conventional agro-ecosystems of the northern Corn Belt focus on a single ecosystem service, over-consume environmental resources and release chemicals to the environment. Organic agro-ecosystems, on the other hand, focus on multiple ecosystem services, consume less environmental resources and retain more nutrients. Adaptation to future changes in climate variability and extremes may require attention to stability and resilience of production, rather than to improve its absolute levels. Two measures of agro-ecosystem yield variation (i.e., temporal variance and coefficient of variation) may be used as indicators of system stability or responsiveness. Farmers, crop consultants and agronomists will benefit from using potential adaptation and mitigation strategies to intensify sustainable agricultural production in the fragile subsistence agro-ecosystems of the Fertile Crescent and optimize and diversify the conventional and organic agro-ecosystems in the northern Corn Belt of the US.

Technical Abstract: A diagnostic approach based on multi-scale integrated analysis and model simulations was employed to identify specific or common biophysical constraints, technological changes and ecological compatibilities of the diverse subsistence and organic agro-ecosystems in the Fertile Crescent of West Asia and the organic and conventional agro-ecosystems in parts of the northern Corn Belt and northern Great Plains of the US. For each agro-ecosystem, soil carbon, total yield, temporal yield variance and yield coefficient of variation per crop rotation were used as sustainability indicators. Thresholds of technologies necessary for the proper functioning and flow of agro-ecosystem services were identified under the most-likely projected climate change scenarios for the next 30 years. The carbon budgets of agro-ecosystems were largely related to the choice of crops, crop sequence, and length of the crop rotation, and were influenced by external inputs, tillage system and removal of crop residues. Carbon depletion is expected to be less in organic and subsistence agro-ecosystems when nitrogen-fixing legumes are included in more diverse crop rotations and when crop residues are incorporated in the soil. Potential nutrient loss to the environment is expected to be significantly larger in conventional systems, and nutrients are expected to be depleted faster over time in subsistence- than in organically-managed soils. Optimal and sustainable agricultural intensification is feasible through agro-ecosystem diversification and the proper integration of genetic and natural resources management. In all agro-ecosystems, for more diverse rotations to be adopted on a large scale, there needs to be large and easily accessible markets for the additional products.