Sustainable utilization of phosphogypsum in agriculture enhanced by mycorrhizal organisms: a new perspective.

backgroundThe extensive stockpiling of phosphogypsum(PG) poses significant environmental challenges, while many agricultural soils in Yunnan Province exhibit sulfur deficiency and low phosphorus availability. Incorporating exogenous nutrients and bio-fertilizers represents a promising strategy to address both issues. Although PG contains valuable nutrients such as phosphorus (P) and sulfur (S) that can support crop growth, its arsenic (As) content may bright pollution risk to crop growth. Arbuscular mycorrhizal fungi (AMF) are known to promote plant growth and nutrients absorption, and alleviate arsenic stress from soil. This study investigated the synergy effects of AMF inoculation and PG amendment on tobacco (Nicotiana tabacum L.) growth, nutrient uptake, and As accumulation.

resultsThe results show that both FM and GA inoculation increased shoot and root biomass of the three tobacco varieties. PG addition significantly increased the plant S concentration, total uptake, and specific absorption rate in ‘KRK26’ plants. Under both FM and the GA inoculation, PG addition significantly increased the plant P concentration and absorbed amount as well as the uptake ratio of P to As in ‘KRK26’ shoots. FM inoculation increased P, S concentration as well as total uptake amount, and the specific absorption rate in all tobacco varieties at each PG treatment level, while reducing As concentration and absorption in ‘YY87’ by up to 22.96% and 20.21%, respectively. GA inoculation significantly increased P concentration, uptake amount, and P specific absorption rate in ‘KRK26’ by 110.61%, 122.39%, and 179.04%, respectively. Moreover, GA inoculation significantly decreased the shoot As concentration and uptake, thereby increasing the uptake ratio of P to As in both ‘NC297’ and ‘KRK26’ plants. Principal component and correlation analyses identified that P and As showed a co-directional change in the absorption process. As absorption was positively correlated with S availability. Soil pH was negatively correlated with plant P uptake(r=-0.50, P < 0.05), S uptake(r=-0.43), As uptake(r=-0.38), soil available P(r=-0.48, P < 0.05) and available S content(r=-0.54, P < 0.05).

conclusionThe combined application of PG and AMF (Especially for GA) can promote the absorption of P and S by tobacco to a certain extent and inhibit the accumulation of As, with the most pronounced effects observed in the ‘KRK26’ variety. Soil pH plays a key role in element bioavailability, and further analysis confirms a synergistic interaction among P, S, and As during plant uptake. These findings provide a reliable practical solution for the safe and sustainable use of PG in agriculture.