Reimagining agriculture with perennial crops : a study on the diffusion of innovation and soil ecosystem services in the new perennial grain Kernza

Abstract: Perennial crops have been identified as a pathway to implement ecological intensification, which in extent could make agriculture more socio-economically and ecologically sustainable. This is a master thesis in Agroecology – a growing scientific discipline that aims to investigate problems in the food system using a holistic and transdisciplinary approach, incorporating and integrating both natural and social sciences to transform the food system. In this context, the present paper has focused on the initial steps of introducing the perennial grain crop Kernza to the United States, applying a systems perspective to integrate early knowledge from experimental farmers with research on plant-soil interactions, comparing the abundance of arbuscular mycorrhizal fungi (AMF) in a perennial settings with their annual monologues. In the first part of the paper, interviews with five experimental farmers across the US are analyzed using an innovation framework to gauge what motivated their choice to grow Kernza, and what other variables might have affected their decisions to adopt the crop at this early time. The results show that these growers represent a variety of typical farmer backgrounds with very different motivations for experimenting with the crop, including using it for its abilities to reduce weed-pressure, earn profits from a new and exciting crop, or to support researchers in developing these crops; where the most common reason to adopt and trial the crop was curiosity and interest in sustainability. It was shown that the most important attributes affecting the diffusion of new innovations like Kernza include their relative advantage, such as the economic benefits for the farmer, Kernza’s soil-building capabilities, and that the complexity of growing the crop can be alleviated by improving the distribution of knowledge. This may be done by creating model farms where the current benefits of the crop can be put on display, and where economic performance in such a context can be highlighted for innovators and early adopters. Furthermore, the results show that these crops could be attractive and relatively easy to implement by farmers that already grow small grains, perennial seeds like lucerne, or otherwise have the knowledge, equipment and socioeconomic means of growing a grain currently in development. But for the crop to reach its current potential, such plantings should consider using Kernza as a dual-purpose crop to make use of both seed and plant residues for forage, primarily on marginal lands that otherwise would not have generated any reasonable income. The second part of the thesis set out to analyze the abundance of AMF in a 3-yr Kernza field, a 1-yr Kernza field, a 1-yr Kernza-lucerne intercrop, and a field planted with winter wheat using PLFA and NLFA-analyses. The results show a significantly higher abundance of the NLFA 16:15 indicative of AM hyphae in the oldest perennial cropping system at a soil depth of 30-60 cm, with similar but not significant differences visible at soil depths 0-5 cm and 5-30 cm. This was in line with the hypothesis that time between disturbance and the perennial nature of these crops should generate more abundant microbial communities than in crop agriculture dominated by high disturbance and annual crops. The implications of these findings are discussed, followed by suggestions for future research topics to enhance the understanding of perennial grains and perennial polycultures, and the interactions between these crops and the soil – innovations that holistically attempt to tackle numerous problems of agriculture at the same time. It is concluded that perennial crops have the potential to become a paradigm-shifting innovation capable of changing the mental models governing agriculture today: from high yields and high input systems reliant on annuals, to resilient farming systems where nature is the measure.