Researchers have found that growing a variety of crops instead of a single crop can increase agricultural yields by limiting the growth of soil pathogens. This study highlights the productivity and stability of diverse plant communities and suggests the application of these principles to home gardening.
A University of Kansas study shows that diversifying crops can increase yields by reducing the availability of soil pathogens, challenging traditional monoculture practices and providing insights applicable to home gardening. A study published in the journal Nature Communications, based on field and greenhouse experiments at the University of Kansas, shows how growing a diverse crop rather than a single plant species can improve agricultural yields: Soil pathogens that are harmful to plants have a harder time thriving.
"It's been commonly observed that diverse plant communities are more productive and stable over time," said James Bever, a senior scientist at the Kansas Center for Biological Surveys and Ecological Research and the University of Kansas Foundation Distinguished Professor of Ecology and Evolutionary Biology. "Pastures with a rich diversity of species show higher productivity. But why has been a mystery."
Mechanisms behind plant diversity benefits
While crop rotation and other farming and gardening practices have long reflected the benefits of plant mixing, new research provides hard data on an important mechanism observed: the abundance of plant-eating microorganisms in the soil.
"Diverse agricultural communities have the potential to suppress pathogens, thereby increasing yields," said Bever. "Our study shows that a major driver is the specialization of pathogens, particularly those that target different plant species. These pathogens suppress yields in low-diversity communities. An important advantage of pasture diversity is that pathogens consume less biomass, leaving more biomass available for other uses, such as raising cattle. The same process is also critical for agricultural production."
Methods and collaborative efforts
The new data were developed at the University of Kansas through field experiments at the KU Field Station (KU Field Station), greenhouse experiments and feedback modeling using computers. This project received a large cooperative grant from the National Science Foundation and the U.S. Department of Agriculture to the University of Kansas.
"We conducted an experiment manipulating the number of plants in the plots and varying amounts of precipitation - we grew from one to six species of plants in a plot," Bever said. "We then assessed the composition of the soil pathogenic microbiota. We found that changes in pathogen composition within a monoculture significantly predicted the composition Yields of cultivation. When different pathogen communities are present, mixed planting can lead to the release of more pathogens from neighbors. The worst case scenario is that adjacent crops have the same pathogen, in which case the crop will experience a double density of challenges, both from the crop pathogen and from the neighbor crop."
At the University of Queensland, Bev's collaborators include associate expert Peggy Schultz, as well as Haley Burrill and Laura Podzikowski, who both received their PhDs at the University of Queensland and are now engaged in postdoctoral research at the University of Oregon and the University of Queensland respectively. Lead author Wang Guangzhou, who worked as a postdoctoral researcher at the University of Queensland and is now affiliated with China Agricultural University in Beijing, participated in the investigation along with co-authors Zhang Fusuo and Zhang Junling. They were joined by Maarten Eppinga of the University of Zurich in Switzerland.
Criticism of monoculture practices
According to Bev, the research opposes the industrial farming practice of growing a single food crop on many acres, a practice commonly known as "monoculture."
"Regarding the practice of monoculture, the idea of promoting plant diversity seems to run counter to popular practice," he said. "Monoculture - the practice of growing a single crop over a large area of land - is driven by technical rather than biological reasons. The practicality of growing and harvesting drives this approach. Traditional Native Americans Multi-species polyculture is the practice in civilian agriculture and in the tropics. In China, there is a movement toward mechanized polyculture production that challenges the dominant monoculture model in the United States. Monoculture must be viewed as a cost-effective model with increased inputs and alternative methods such as crop rotation be explored for long-term management of pathogens."
Bever says mixing plants in different plots can be beneficial to home gardeners and others who grow plants.
"When gardening, you don't rely on mechanical planting and mechanical harvesting," he said. "It's certainly more beneficial to have a mix of crops - a heterogeneous mix in the plot - where we can alternate crops. It's more efficient than if you have a lot of rows of the same crop next to each other." Control pathogens. If you have four disconnected plots in your backyard, you shouldn't have all your tomatoes in one plot, all your squash in another, and herbs in a third - mixing them together can reduce pathogens.
Impact of biodiversity on pathogens
Ultimately, Bever said his team's findings suggest that biodiversity inhibits pathogen growth, but this is not evident outside the plant kingdom. In fact, this idea is controversial in animal systems.
"Our unambiguous results in the plant kingdom are in stark contrast to the complexity of this literature in the animal kingdom," he said. "The study of pathogens in ecology has been controversial in the context of recent concerns about pathogens, such as COVID. The effect of diversity on pathogen effects, whether it increases or decreases, has been controversial."
"Our results in plants suggest that people are more concerned with the reduction in pathogen transmission following increased diversity than with an increase. In our study, pathogens were studied, including those living in the soil. A similar pattern was observed among foliar pathogens, which is detailed in a forthcoming paper. The controversy stems from the different effects of pathogens in the animal and plant kingdoms."