Using fungi in the place of fertilizers for crops is a developing area of research that could lead to new farming systems which reduce the harmful contributions of fertilizers on the environment.
A lot of agricultural crops have been bred for certain desirable characteristics, and some of this breeding has reduced natural symbiotic relationships between crops and fungi in the soil. However, a recent study reintroduced fungi to wheat crops, and the fungi provided the wheat with phosphorous and nitrogen under multiple different climate variables. Under high atmospheric CO2 levels, the fungi continued to provide the crop with the same amount of nutrients, indicating that fungi may be a reliable source of nutrients for important crops even under future/projected carbon levels.
Fertilizers contribute to carbon emissions, can cause eutrophication in water systems, and may be poisonous to organisms that ingest them, so the relationship of crops and fungi looks promising in terms of helping out the environment. Of course, more research is necessary, especially since fungi have been found to occasionally parasitize crops, but in this particular study, the fungi did not take more carbon from their partners than usual even under the high CO2 levels.