📄 agriculture

Arbuscular mycorrhizal fungi show potential to substantially increase global grain yields

This study estimates that inoculating global maize, wheat, and rice crops with arbuscular mycorrhizal fungi could increase total cereal production by 12.6% (341 million metric tons), highlighting the significant, yet often overlooked, potential of soil biological communities to enhance global food security.

Original authors: Aaron Prairie, Nathaniel Mueller, Marian Hsieh, Peiyu Cao, Steven Fonte

Published 2026-08-10

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CC BY 4.0

Original authors: Aaron Prairie, Nathaniel Mueller, Marian Hsieh, Peiyu Cao, Steven Fonte

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine the soil beneath our feet not as mere dirt, but as a bustling, invisible city. In this underground metropolis, tiny organisms like fungi and bacteria are the hardworking citizens, constantly recycling nutrients, building soil structure, and protecting plants from disease. Among these citizens, a special group called arbuscular mycorrhizal fungi (AMF) acts like a super-powered delivery service. These fungi form a symbiotic partnership with plant roots, sending out long, thread-like extensions that reach far beyond the plant's own roots to grab water and nutrients—especially those that are hard to find, like phosphorus—and hand them over to the plant. In exchange, the plant feeds the fungi sugar. While we know these fungi are everywhere and incredibly helpful, we often treat them like background noise in farming, focusing instead on synthetic fertilizers and heavy machinery. The big question scientists have been asking is: If we actually pay attention to these underground helpers and help them do their job, could they feed more of the world?

This paper takes a giant leap to answer that question by looking at the three biggest crops that feed humanity: maize (corn), wheat, and rice. The researchers didn't just guess; they combined a massive collection of past field experiments with detailed global maps of soil types, farming practices, and crop yields. Think of it as taking thousands of small puzzle pieces from different farms around the world and assembling them into one giant, high-definition picture of what could happen if we optimized these fungal partnerships everywhere.

The study suggests that if we could boost the function of these fungi across the globe, we might see a massive jump in food production. Specifically, the authors estimate that AMF inoculation (helping the fungi grow and work better) could increase global cereal production by 12.6%. To put that in perspective, that's an extra 341 million metric tons of grain every year. That is enough food to fill a mountain of corn and wheat that would dwarf any single city's skyline.

However, the story isn't the same everywhere. The paper finds that the "superpowers" of these fungi depend heavily on the neighborhood they live in. In places where farmers use very little fertilizer—often in low-income regions like Sub-Saharan Africa and parts of Southeast Asia—the fungi are absolute rock stars. In these nutrient-poor soils, the fungi can boost yields by more than 20%, acting as a lifeline for crops that would otherwise struggle. In contrast, in heavily fertilized industrial farms, the plants are so well-fed by synthetic chemicals that they don't need the fungi as much, and the yield boost drops to around 11%. It's like a person who is already eating a full buffet; giving them a vitamin supplement doesn't help them grow much taller, but for someone who is hungry, that supplement is a game-changer.

The researchers also point out that this potential isn't a guaranteed "win" just by sprinkling some fungus powder on fields. The paper argues that success depends on context. If the soil is too alkaline (high pH) or too dry, or if the specific type of fungus introduced doesn't match the local crop, the benefits might be small or even non-existent. Furthermore, the study highlights that we don't need to just add new fungi; we often need to stop hurting the ones that are already there. Practices like reducing tillage (not churning up the soil) and adding organic matter can strengthen the native fungal networks already living underground.

So, what does this mean for the future? The paper suggests that while we can't rely on fungi alone to solve every food problem, they represent a huge, underused tool. By managing our soils to support these microscopic allies, we could close the gap between how much food we grow and how much we need, especially in areas where farmers can't afford expensive fertilizers. It's a reminder that the secret to feeding the future might not just be in the sky or in a factory, but right beneath our feet, waiting for us to let them do their job.

Technical Summary: Global Potential of Arbuscular Mycorrhizal Fungi to Increase Grain Yields

Problem Statement
Soil organisms, particularly arbuscular mycorrhizal fungi (AMF), are critical regulators of nutrient cycling, soil structure, and plant resilience. However, their contributions to agricultural productivity are largely absent from global yield models and agronomic decision-making. While field studies document yield benefits from AMF inoculation, especially under low-input conditions, the global-scale yield potential of AMF remains unquantified. This gap prevents researchers and policymakers from evaluating where improved management of soil biodiversity could meaningfully support food production or reduce reliance on synthetic fertilizers. Furthermore, intensive farming practices often suppress AMF colonization, leaving a significant opportunity to restore function through management or targeted interventions.

Methodology
The study provides the first global-scale estimate of potential yield gains from AMF across the world's three dominant cereal crops: maize, wheat, and rice. The authors employed a spatially explicit modeling approach combining empirical response data with global gridded datasets:

Data Sources:
- Yield and Area: Crop yield and harvested area data were obtained from SPAM 2020 v2.0 at a 5 arcminute resolution.
- Soil and Management: Soil properties (pH, total nitrogen) were derived from SoilGrids v2.0. Plant-available nitrogen (paN) was estimated from total nitrogen. National, crop-specific fertilizer statistics were sourced from the IFDC–FAO Fertilizer Use by Crop (FUBC) database.
- AMF Response Data: Yield responses were parameterized using crop- and subgroup-specific log-response ratios (lnRR) from a global meta-analysis of 168 in-field inoculation studies (402 trials) by Zhang et al. (2019).
Modeling Approach:
- The baseline AMF effect ( $AMF_{base}$ ) was established using crop-specific mean lnRR values (maize: 13.4%, rice: 17.1%, wheat: 17.2%).
- Context dependence was incorporated using moderator coefficients ( $k$ ) derived from statistically significant subgroups in the meta-analysis. These moderators included soil pH, an interaction between nitrogen fertilizer use and plant-available nitrogen, and phosphorus/potassium fertilizer status.
- The final AMF yield multiplier ( $M$ ) for each grid cell was calculated as: $M = AMF_{base} \times k_{pH} \times k_{N \times paN} \times k_{P} \times k_{K}$ .
- Potential production gains were estimated by applying this multiplier to baseline yield maps, computing the difference between inoculated and uninoculated (current) yield surfaces, and multiplying by harvested area.
Uncertainty Analysis: Uncertainty was propagated using Monte Carlo sampling (1,000 draws), sampling lnRR values from normal distributions based on reported 95% confidence intervals to generate a distribution of global production gains.

Key Results
The analysis indicates that enhancing AMF function has the potential to increase global cereal production by an average of 12.6%, corresponding to approximately 341 million metric tons (MMT) of additional grain (95% uncertainty interval: 232–438 MMT).

Crop Specificity: Yield gains varied by crop, with the highest potential for wheat (16.0%) and rice (15.9%), and a slightly lower but still substantial gain for maize (12.3%).
Contextual Drivers: The strongest moderator of yield benefits was nutrient context.
- Low-Input Systems: In systems with limited soil nitrogen availability and no fertilization (common in smallholder contexts), predicted gains exceeded 20%.
- Intensive Systems: In intensively fertilized systems, predicted gains were approximately 11%. This aligns with the understanding that high fertilizer inputs reduce plant dependence on AMF.
Geographic Distribution:
- Relative Increases: The largest relative yield increases are projected for low-input systems in Sub-Saharan Africa and parts of Southeast Asia.
- Absolute Production: The greatest absolute production gains are concentrated in South and East Asia due to the sheer volume of production in these regions.
Constraints: The study notes that high soil pH and arid conditions can reduce AMF benefits. Additionally, in areas where native AMF communities are already well-established or where introduced strains are poorly matched, inoculation may have negligible or negative effects.

Significance and Claims
The paper claims to provide the first quantitative, global-scale estimate of the potential yield gains from AMF inoculation. The authors argue that these results highlight the under-recognized role of soil biological communities in supporting global food production.

The study posits that improved management of AMF could add more than 300 MMT to global grain production, with benefits being particularly critical for low-input systems. The authors suggest that this biologically-grounded solution offers a pathway to align food security with sustainability, potentially reducing reliance on synthetic fertilizers and associated reactive nitrogen losses and greenhouse gas emissions. However, the paper maintains a modest tone regarding implementation, noting that realizing these gains depends on applied research to improve inoculant quality, resolve context dependence, and establish economic viability through region-specific field trials. The analysis serves as a quantitative basis for prioritizing where AMF-focused interventions are most likely to close yield gaps.

Technical Summary: Global Potential of Arbuscular Mycorrhizal Fungi to Increase Grain Yields

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