Figure 5.
inoculation when planting crops with arbuscular mycorrhizal fungal inoculum is a cost-effective option for re-establishing the benefits of the symbiosis in the farmer’s field.
What we know Te work of Rodale research
collaborator, Dr. David Douds of the USDA Agricultural Research Service, suggests that healthy mycorrhizal fungi populations in organic systems increase crop productivity while sequestering carbon. Soils farmed with organic systems have greater populations of mycorrhizal fungi. Overwintering cover crops supply energy to fuel the activities of mycorrhizal fungi in the organic system, in contrast to the conventional systems, which generally have a significantly greater fallow period. Reduced chemical use in the organic system also provides an environment more favorable to the spread of the mycorrhizal fungi. Healthy populations of mycorrhizal fungi are associated with higher levels of glomalin production and increased carbon levels on farms. Yields can also increase. For example,
22 FUNGI Volume 14:4 Fall 2021
in a 7-year study mycorrhizal fungi significantly increased vegetable production even in an existing high fertility environment (Douds et al., 2016). Douds’s research suggests that a small amount of added mycorrhizal fungi can be substituted for a large amount of fertilizer in the growing of crops. Te result: less CO2
emitted
because of fewer fertilizer needs and less pollution of water resources because of fertilizer runoff. Many of today’s farming practices can
combine methods that increase carbon content in the soil. Instead of relying on synthetic pesticides and fertilizers, regenerative farming entails symbiotic and soil carbon-building practices such as growing legumes with associated nitrogen-fixing bacteria, cover crops, diversified crop rotations colonized with mycorrhizal fungi, and animal manures and compost (Pimintel et al., 2005). Tese are not pie-in-the-sky approaches but are proven ways to increase the carbon content of soil. What we need is more photosynthesis and practices that encourage life and carbon inputs in the soil. Healthy soils with vigorously
growing plants are a carbon sponge.
Conclusions For decades after World War II,
massive inputs of fossil fuels, intensive tillage, chemical fertilizers and pesticides have helped increase crop productivity at the expense of topsoil erosion, organic matter loss, destruction of mycorrhizal fungi, and loss of precious soil carbon that turned to greenhouse gasses. Tese massive chemical inputs essentially covered up poor soil management practices. For three straight decades, carbon dioxide levels have skyrocketed, acres of productive farmland have declined, and farm input costs have increased. Where can we put carbon dangerously accumulating in the air? Tere is one practical and cost-effective approach—to put it back where it belongs, in the soil. Much remains to be learned. What we
don’t know about mycorrhizal fungi far exceeds what we do know. But one thing is becoming certain. Teir effectiveness in sequestering carbon in the soil and reducing carbon emissions into the air cannot be overlooked. Considering
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