A recent study conducted at the University of Kansas has shed light on the mystery behind why planting diverse crops leads to higher agricultural yields. The research, published in Nature Communications, reveals that the presence of various plant species makes it harder for harmful soil pathogens to thrive, resulting in increased productivity.
The benefits of planting a mix of crops have long been recognized in farming and gardening practices, but until now, the underlying reasons have remained unclear. The study provides solid evidence for one important mechanism behind this phenomenon: the abundance of microorganisms in the soil that feed on plants.
Lead author James Bever, senior scientist at the Kansas Biological Survey & Center for Ecological Research, explains that diverse agricultural communities have the potential to keep pathogens at bay, resulting in greater yields. The research highlights the specialization of pathogens, particularly those specific to different plant species, as a major driver of this effect. In low-diversity communities, these specialized pathogens suppress yields. However, in diverse plant communities, less biomass is consumed by pathogens, allowing more biomass to be utilized for other purposes, such as cattle feed or agricultural production.
The study was conducted using field experiments at the KU Field Station, along with greenhouse assays and computer modeling. By manipulating the number of plant species in each plot and varying precipitation levels, the researchers were able to evaluate the composition of the soil-pathogen microbiome. The results showed that the variation in pathogen composition in monocultures significantly predicted the overall yield. When distinct pathogen communities were mixed, the release of pathogens from neighboring crops increased. The worst scenario occurred when neighboring crops shared the same pathogens, leading to a double density of pathogens affecting the crops.
The findings challenge the prevailing practice of monoculture, which involves planting vast areas with a single crop. Monoculture is primarily driven by technological reasons rather than biological ones. In contrast, traditional Native American agriculture, tropical practices, and the emerging mechanized polyculture movement in China promote the benefits of planting multiple species together. The study suggests that crop rotation and planting heterogeneous mixes of crops can effectively manage pathogens over time, reducing the need for increased inputs.
The implications of the research extend beyond large-scale agriculture to home gardeners and plant cultivators. Mixing crops in various plots, or even alternating rows of different crops, can help control pathogens more effectively than planting large monocultures. The study emphasizes the importance of diversity in plant communities to safeguard against pathogen growth.
