Fungi from Abandoned Phosphate Mines Unlock Soil Phosphorus and Boost Crop Yields

Phosphorus is the quiet bottleneck of global agriculture. Although the element is abundant in the Earth’s crust, most of it in soils is locked into insoluble mineral forms that plant roots simply cannot absorb, forcing farmers to compensate with mined phosphate fertilizers that are themselves a finite and geopolitically concentrated resource. A new study published in the journal Plant and Soil offers a strikingly elegant twist on this problem: researchers turned to abandoned phosphate mines—landscapes usually dismissed as industrial scars—and found fungi that thrive there, capable of dissolving the very phosphorus that immobilized soils hold hostage. When assembled into a synthetic community and applied to forage plants, these fungi increased shoot biomass by as much as 85 percent while simultaneously improving the nutritional quality of the harvest.

The research team, led by scientists at the Kunming Institute of Botany of the Chinese Academy of Sciences, conducted their field-scale hunt at a phosphate mining site in Haikou, near Kunming in Yunnan Province, China. The logic behind the location is compelling. Phosphate mine environments are extreme habitats where microbes have been subjected to intense selective pressure to survive amid high concentrations of poorly soluble phosphate minerals, fluctuating pH, and nutrient stress. Any fungus that can flourish under such conditions has, in effect, already passed a rigorous natural screening process for the exact traits agronomists want: tolerance to harsh chemistry and a powerful appetite for insoluble phosphorus.

The scale of the isolation effort was considerable. From soil and plant samples collected at the mining site, the team obtained 609 fungal isolates. Through successive screening rounds on media designed to reveal phosphate-solubilizing ability—classic assays in which microbes grow on insoluble calcium phosphate and clear halos form around colonies that can dissolve it—69 isolates demonstrated phosphate-solubilizing potential. From this shortlist, three strains ultimately earned a place in the final formulation: Aspergillus sp. 5C-22, Diaporthe sp. 7C-37, and Irpex sp. 9B-08. The selection criteria went beyond raw solubilization efficiency. The winning strains also tolerated a wide range of pH values and temperatures, and they were easy to cultivate in bulk—practical requirements that often doom promising laboratory microbes before they ever reach a field.

With the three strains in hand, the researchers assembled them into a synthetic community, or SynCom, a deliberately constructed microbial consortium. The SynCom approach reflects a growing consensus in soil microbiology: single-strain inoculants frequently underperform in real soils, where they face competition, predation, and unpredictable environmental conditions, whereas consortia of complementary strains tend to be more robust. A recent meta-analysis cited by the authors supports this view, showing that inoculated microbial consortia generally outperform single strains in living soil. In this study, the three fungi were chosen not just for individual prowess but for the possibility that their combined activities—organic acid secretion, enzyme production, and rhizosphere modification—would be synergistic rather than redundant.

The performance tests were carried out in acidic, phosphorus-immobilized soil, the kind of soil where phosphorus deficiency is most stubborn because available phosphate rapidly binds to iron and aluminum oxides and becomes unavailable to roots. Three forage species served as the test plants: elephant grass (Pennisetum purpureum), giant reed (Arundo donax), and maize (Zea mays). These species matter well beyond the laboratory. Forage crops underpin livestock production worldwide, and their nutritional quality—crude protein, crude fat, and soluble sugar content—directly affects animal health and the economics of meat and dairy systems. A treatment that improves both yield and feed quality therefore addresses two bottlenecks at once.

The results were unambiguous. Inoculation with the fungal SynCom significantly promoted the growth of all three species, increasing shoot biomass by 35.5 to 85.2 percent depending on the plant. Phosphorus uptake rose as well, confirming that the growth gains were rooted in improved access to the element rather than in some indirect growth stimulation. Perhaps most striking for an agricultural audience, the nutritional profile of the forage improved substantially: crude protein content increased by 25.9 to 38.5 percent, while crude fat and soluble sugar concentrations also climbed. Because phosphorus is a structural component of nucleic acids, membranes, and the energy currency ATP, its scarcity ripples through plant metabolism; relieving that scarcity appears to have allowed the plants to build richer, more protein-dense tissues.

What mechanism underlies these gains? The authors describe a synergistic process combining direct solubilization of phosphorus and potassium with host-specific modulation of the rhizosphere—the narrow zone of soil surrounding and influenced by plant roots. Phosphate-solubilizing fungi typically dissolve insoluble phosphates by excreting low-molecular-weight organic acids such as oxalic, citric, and gluconic acids, which protonate and chelate the cations that bind phosphate, releasing it into soil solution. The fungi may also secrete phosphatase enzymes that liberate phosphorus from organic compounds. In this study, the SynCom consistently boosted the activities of key soil enzymes, including acid phosphatase, urease, and nitrate reductase—enzymes central to phosphorus mineralization and nitrogen cycling, respectively. The elevation of urease and nitrate reductase activity suggests the consortium did not merely unlock phosphorus but also invigorated the broader nutrient-cycling machinery of the rhizosphere.

One of the study’s most scientifically interesting findings, however, is a note of caution. The net influence of the SynCom on rhizosphere nutrient pools and soil properties was not uniform; it was jointly regulated by the physiology of the host plant. In other words, the same fungal community produced different rhizosphere outcomes in elephant grass, giant reed, and maize. The authors highlight this as evidence for the importance of functional plant–microbe compatibility—the idea that an inoculant’s success depends not only on the microbes’ intrinsic capabilities but on how those capabilities interact with a particular plant’s root architecture, exudate profile, and nutrient demand. This host-specificity is a recurring theme in SynCom research and a crucial design principle for the next generation of biofertilizers: matching consortia to crops may matter as much as selecting the consortia themselves.

The broader significance of the work lies in how it reframes two problems as one solution. Abandoned phosphate mines are typically viewed as environmental liabilities requiring costly remediation, while phosphorus-immobilized agricultural soils are viewed as an agronomic liability requiring ever more fertilizer input. This study suggests the two liabilities can offset each other: mine-adapted fungi, evolved in the harshest phosphorus-rich environments, can be redeployed to mobilize the vast reserves of native soil phosphorus that conventional agriculture ignores. Because the approach mobilizes phosphorus already present in the field rather than importing it, it offers a sustainable alternative to conventional fertilization, with potential benefits for reducing dependence on mined rock phosphate, curbing fertilizer runoff that pollutes waterways, and lowering the carbon and financial costs of crop production.

There are, of course, steps between a greenhouse trial and a farmer’s field. The researchers note that their datasets are available on reasonable request, and the study was supported by Yunnan provincial research programs, signaling institutional commitment to developing the line of work. Scaling fungal inoculants will require solving formulation, shelf-life, and application challenges, and field performance must be validated across diverse soils, climates, and cropping systems. Yet the conceptual advance is secure and, in the best sense of the phrase, viral science: a self-reinforcing idea that waste landscapes can seed biological solutions to one of agriculture’s oldest constraints. If follow-up studies confirm these results at scale, the abandoned phosphate pits of Yunnan may be remembered not as scars of extraction, but as the discovery sites of the microbes that helped agriculture loosen its grip on finite rock phosphate.

Subject of Research: Phosphate-solubilizing fungi from abandoned phosphate mines as synthetic communities for mobilizing soil phosphorus and improving crop yield and nutrition

Article Title: Harnessing phosphate mine-derived phosphate-solubilizing fungi boosts plant yield and nutritional quality in phosphorus-immobilized soil

Article References: Tang, H., Li, Y., He, Z., Huang, X., Hu, N., Li, X., Li, J., Wang, R., Gui, H., Xu, J., Li, Y., & Li, X. (2026). Harnessing phosphate mine-derived phosphate-solubilizing fungi boosts plant yield and nutritional quality in phosphorus-immobilized soil. Plant and Soil. https://doi.org/10.1007/s11104-026-09065-7

Image Credits: AI Generated

DOI: 10.1007/s11104-026-09065-7

Keywords: phosphate-solubilizing fungi, phosphorus, synthetic community, SynCom, rhizosphere, soil microbiology, sustainable agriculture, phosphate mine, forage crops, biofertilizer, acid phosphatase, plant nutrition