Search

Soil process models such as RothC typically assume soil organic carbon (SOC) is in equilibrium at the beginning of each simulation run. This is not likely to be true in the real world, since recalcitrant SOC pools (notably, humified material) take many decades to re-stabilize after a land use change. The equilibrium assumption stems from a spinup method in which the model is run under a single land use until all SOC pools stabilize. To overcome this, we demonstrate an alternative spinup procedure that accounts for historical land use changes. The "steady-state" and "historical" spinup methods both impute unknown C inputs such that the modeled SOC matches empirical measurements at the beginning of the simulation and set initial SOC fractions. Holding all other parameters equal, we evaluated how each spinup affects SOC projections in simulations of agricultural land use change in the U.S. state of Vermont. We found that projected SOC trajectories for all land use scenarios are sensitive to the spinup procedure. These differences are due to disparities in imputed below-ground plant-derived carbon between the two procedures. Compared to the steady-state, imputed C in the historical spinup is higher for land uses that increase SOC (e.g., adoption of regenerative practices) and lower for land uses that decrease SOC (e.g., a transition from pasture to crops), due to the time window within which land use changes are assumed to have occurred. The novel historical spinup procedure captures important dynamics commonly missing in previous studies, representing an advancement in soil process modeling. [ABSTRACT FROM AUTHOR]

Dairy farmers face persistent market shocks that force creative diversifications to enhance their resilience. In the summer of 2021, corporate dairy companies canceled over 100 contracts with organic dairy farmers in New England, a market shock to the industry across the Northeast. To better understand how farmers cope with market shocks in small dairy production, we studied small-scale dairy farms from the perspective of social ecological resilience, exploring the role of diversification in small dairies in Vermont and New Hampshire: which strategies are most effective, what factors influence diversification, and the barriers to diversification. Data came from interviews with dairy farmers and advocates from multiple sectors involving ecological, economic, institutional, cultural, and personal domains. We highlight why, how, and with what support small-scale New England dairy farmers have adapted, supplemented, or transformed their dairy operations. Dairy farms exhibited high levels of diversification, motivated by a range of economic, ecological, and personal incentives. Predominant diversification pathways include (1) higher premiums from organic or directly marketed liquid milk, (2) value-added dairy products, (3) nondairy farm products, and (4) efficient and sustainable land management practices. Our findings suggest that what supports diversification is the transparent and open sharing of knowledge among a network of farmers, based on strong interpersonal relationships. Institutions such as government programs and dairy cooperatives frame diversification, which is best supported by funding flexibility and accessibility of information. Diversification has enabled greater resilience for dairy farmers, despite continued dairy market volatility in the Northeast. Without structural and institutional changes, dairy viability will continue to be in jeopardy, and the need for diversification will remain. [ABSTRACT FROM AUTHOR]