Dynamic Assessment of Current Management in an Intensively Managed Agroecosystem. (August 2016) - Wilson, Christopher G.
Abstract: To assess management impacts on the functionality of intensively managed agroecosystems, a modeling framework was developed with a bottom‐up approach and spatially distributed, process‐based models. The framework is equipped with dynamic, data‐informed indicators and indices to illuminate the factors influencing sustainability. The proposed dynamic indices consider natural and human aspects of an agroecosystem such as erosion, biogeochemistry, and economics. Most current indicators are static, or slow‐changing, soil characterization parameters that reflect better long‐term interactions between landscape features, climate, and biology. However, the ever‐changing land management and climate necessitates the use of dynamic parameters that reflect agroecosystem responses to different land management on similar timescales (e.g., seasonally). Our framework examines the performance of different ecosystem services including crop productivity, carbon storage, and net income under three different strategies with varying degrees of tillage intensity. The strategy with the highest intensity produced the highest yields, but also had the highest production costs. The second most intense strategy also had high yields, as well as the highest net income. However, these two strategies produced high erosion rates, which depleted the recalcitrant soil carbon, a critical component of system productivity and health. The index that provided the clearest picture of improvement within an agroecosystem was the Carbon Management Index ( CMI ), which incorporates carbon lability and the implicit accounting of soil carbon redistribution from erosion. The CMI for the more intense strategies decreased in recent years, showing that they are not sustainable despite their high short‐term productivity or profitability. The least intense strategy had the lowest Soil Organic Carbon (SOC) depletion through erosion and the highest CMI with a trend that is still‐increasing through the present. Our study shows that to augment SOC storage, it important not only to increase the overall organic matter input, but also increase the amount of recalcitrant carbon in the soil and the longevity of all soil carbon through aggregate formation.