In acidified soils, fungi are an alternative to chemical fertilisers

According to Chinese research, the inoculation of mycorrhizal fungi results in a significant growth of the plant biomass of soybeans as well as the development of an optimal microbiome in the soil

by Matteo Cavallito

 

The use of mycorrhizal fungi in acidified soils, which are characterised not only by low pH but also by phosphorus deficiency, helps to promote fertility while providing an alternative to chemical fertilisers. This is supported by a study by researchers at Nanjing Agricultural University.

“Traditional methods to improve soil phosphorus involve chemical fertilization, which can have environmental drawbacks,” a statement says. “Mycorrhizal fungi offer a promising alternative by enhancing nutrient uptake and soil health.”

Microorganisms, phosphorus and nitrogen

“Acidic soils stand for the majority of the world’s potential agricultural land and their characteristics (…) directly impact crop roots and inhibit the absorption of water and nutrients, thereby reducing crop growth and yield,” the study explains. Among the victims of this phenomenon are also soybean crops, which “predominantly take place in low-pH areas” in the world, the researchers point out. In this context, the focus on the potential expressed by microorganisms is no coincidence.

Microbes, in fact, “contribute to the growth, fitness, and health of aboveground plants” thanks to a number of special characteristics.

These include “their capacity in solubilizing phosphates, producing hormones, fixing nitrogen, affecting plant metabolism (e.g., increasing mineral and water uptake), improving root development.” In addition, the researchers emphasise, to their ability to increase enzyme activity and to combat certain pathogens. Mycorrhizal fungi, in particular, “are responsible for up to 80% of nitrogen and 75% of phosphorus absorption by plants by employing the extensive hyphal network to increase the soil volume that can be explored by plants for phosphate.”

The study

The study compared the effects of mycorrhizal fungi inoculation and phosphorous fertilisation on soybean growth. Authors, in particular, habìve been focusing on plant biomass and the composition of the rhizosphere microbiome. Investigation showed that the biomass of soybean PT6, the variety with the highest phosphorous efficiency, “was significantly increased by 46.74%-65.22% through arbuscular mycorrhizal fungi (AMF) inoculation,” the study explains.

The analysis, moreover, revealed that fungal inoculation altered the composition of the microbial community in the rhizosphere (the portion of the soil where the roots develop) of soybean by favouring the presence of beneficial microorganisms.

“Most nitrogen (N)-fixing bacteria and some functional genes related to N-fixation were abundant in endospheric layer, as were the P-solubilizing Pseudomonas plecoglossicida, and annotated P-metabolism genes,” the study continues. “These N-fixing and P-solubilizing bacteria were positive correlated with each other.”

Fungi are a sustainable solution

The data collected, the researchers conclude, have important implications for sustainable agriculture. “Our findings demonstrate the significant potential of AMF in enhancing soybean growth in phosphorus-deficient acidic soils,” says Guihua Lu, co-author of the study. Moreover, he adds, “This sustainable approach not only improves plant productivity but also contributes to soil health, offering a viable alternative to traditional fertilization methods.”

Future research, therefore, should focus on extending the application of microbial inoculants to other crops and different kind of soils. Further supporting the development of sustainable agricultural practices that utilise natural plant-microbe interactions to improve crop yields.