Resilience of Montana's agroecosystems to economic and climatic change
Lawrence, Patrick Glenn
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Semiarid dryland agricultural systems in the western United States are faced with a highly uncertain production environment that complicates decision-making and makes static agronomic prescriptions unreliable for maintaining sustainability. The primary sources of uncertainty for farmers are weather, fluctuations in prices, and site-specific environmental and ecological variability, some of which may be amplified by climate change. To effectively respond to the risks posed by these uncertainties requires knowledge of the vulnerability of these agricultural systems. The aim of this dissertation was to meet this need for Montana by analyzing the economic resilience of the state dryland agricultural systems at site-specific and county-wide scales. To begin, a framework was created to integrate weather, prices, nitrogen inputs, and spatial soil variability within a statistical model for site-specific crop responses and net returns. Simulations suggest that six crop years of simulated data collection and parameter tuning were required to derive an accurate model, suggesting that an extended period of observation and targeted nitrogen rate experimentation was required to optimize spatial fertilizer management. The framework was subsequently applied to a spatiotemporal precision agricultural dataset from a farm near Great Falls, MT, and was modified to account for several crop rotations and different farmer risk preferences. Regardless of farmers' level of risk aversion, winter wheat-pea rotations resulted in higher value (utility) for the farmer than winter wheat-fallow and continuous winter wheat rotations. For most levels of risk adversity, it was also optimal to apply no nitrogen fertilizer. Net returns at the field site were always threatened by drought. Subsequently, a qualitative analysis of farmer adaptability in Montana based on survey and interview data determined that farmers had few options for responding to drought but were more adaptable to high input prices. On-farm experimentation and crop rotations could greatly increase adaptability in the future. Finally, simulations of alternative price, precipitation, and crop rotation scenarios were completed. The most resilient agricultural systems were located in northeastern Montana where pulses have been more widely adopted; systems in north-central Montana were less resilient. State-wide, over 50% of dryland farmers may not be resilient to future economic or climatic variability.