We've all heard that diversity is a good thing, but how well do we understand just want diversity really is and how losing it affects cropping systems.
Attendees at the No-till on the Plains conference in late January got a chance to learn more about one important feature of diversity – arbuscular mycorrhizal fungi – from one of the top experts in the field, Wendy Taheri, founder of the research company, TerraNimbus.
Taheri holds a doctorate in ecology and evolutionary biology from Indiana University. Her graduate research demonstrated that selection for the best AMF communities could increase plant biomass as much as 69%.
She worked two consecutive terms with USDA, focusing on developing molecular tools that would allow routine assessments of AMF in agricultural soils and on manipulating cover crops to select the best microbial community for the subsequent cash crop.
There are seven types of mycorrhizal fungi, she said, but the important characteristic is that they form a mutually beneficial symbiosis with another organism, typically a plant.
Almost all flowering plant – 99% -- form some sort of mycorrhizal association. The exceptions are Brassicaceae (mustard family), which includes canola, radish, broccoli, spinach, cauliflower and cabbage, and Amaranthaceae, which includes pigweed and beets.
It is the entire community of AMF that conveys multiple benefits to plants, Taheri said. Those benefits include increased soil fertility, better soil structure with increased water holding capacity, more plant nutrients for people and livestock, reduced use of harmful chemicals, elimination of nutrient runoff, increased plant nutrient use efficiency, especially phosphorus, increased essential oil production, protection from nematodes, protection from fungal and bacterial diseases, drought tolerance, salinity resistance, earlier flowering, more flowers and fruit, more biomass and better yields, sequestration of carbon in the soil, and strong attraction to pollinators.
Kansas farmers do not need to be reminded of the consequences of soil erosion, particularly to wind. And many farmers are already aware of the benefits of cover crops in preventing erosion. However, cover crops also help build the complex soil food web that that in turn builds healthy soil, according to Taheri.
The idea, she said, is to build niches where different organisms can thrive in the soil and that means having a diversity of plants growing. The more diversity, the more niches you have.
"Even small increases in plant diversity can yield large increases in microbial diversity," she said. "Plant diversity increases the complexity of the soil food web which is responsible for the cycling and availability of nutrients to plants."