Comparative Multifunctionality of Dryland Annual and Perennial Grain Production Systems in a Mediterranean Climate

Agricultural stakeholders are becoming increasingly aware of the need for sustainable food systems. In a shift from an agricultural paradigm that prioritizes yield, there is now growing interest in multifunctional food systems that simultaneously promote environmental integrity while also providing adequate yield and nutrition. An investigation into how current and proposed alternatives to annual grain systems address the multifaceted objectives of food system sustainability is necessary given that annual grains currently comprise nearly 70% of earth’s cultivated land and provide majority of the world’s food. Furthermore, it is crucial to conduct research on these grain systems in highly productive and economically valuable agroecological regions, such as California (CA). As the largest and most diverse agricultural state in the U.S., CA provides market opportunities while also heralding what current and future food systems must overcome to maintain food supply amid projected water and weather extremes. Thus, we investigated the multifunctionality of a tilled annual wheat system and two proposed alternatives, no-till annual wheat production and novel perennial grain production, in the Mediterranean climate of California. We measured plant and soil parameters for three years in intermediate wheatgrass or IWG, no-till annual wheat, and tilled annual wheat at four nitrogen rates. IWG had significant fluctuations in aboveground biomass (AGB) and had the highest soil carbon (C) mineralization at each soil depth. No-till wheat had stable AGB and the highest soil C stabilization and microbial biomass in the topsoil, which suggests plant productivity and a lack of soil disturbance over time are key factors underpinning enhanced soil C stabilization and gains in microbial biomass in the topsoil. Yield stability, soil carbon storage and nitrogen use efficiency (NUE) were then compared among the three systems using a multifunctionality framework. IWG had large interannual fluc