By Fernanda Castillo
Saline and alkaline stress on soil creates problems such as loss of vegetation, decreased nitrification rates, loss of available phosphorous, and of course, high pH (Guo et al. 2021). As a result, these environments are low in available nutrients and face degradation. A 2024 study focuses on phosphorus-solubilizing bacteria (PSB), and how they interact with soil microbial composition, nutrient cycling, and plant resilience in coastal wetlands (Sun et al.). In saline and alkaline soils, beneficial PSB such as Bacillus and Exiguobacterium have shown to significantly boost plant growth. These bacteria lower soil pH, ensuring nutrients like phosphorous, nitrogen, and potassium are more available for plants (Sun et al. 2024).
Phosphorous is already present in the soil. However, high pH causes the phosphorous to bind to calcium that is present in alkaline soil. This creates a form of phosphorous that plants are unable to use for chemical reactions such as photosynthesis. Now, here is where the bacteria get to work. The bacteria that were studied help release the phosphorous by secreting organic acids, which lower the soil's pH and bind to the calcium-phosphate molecules. This makes the phosphate soluble, which then makes it easier for plants to use it (Sun et al. 2024).
 |
| A diagram of phosphate-solubilization mechanisms (Iftikhar et al. 2023). |
The study tested these PSB strains on soils both treated with saline and alkaline solutions, and on non-stressed conditions, which were treated with sterile water. The soils were then used to plant Suaeda salsa (L.) Pall, an annual herb resistant to salinity and drought that is commonly found in coastal wetlands (Li et al. 2021). These tests found that the PSB strains improved plant growth only on the plants growing in the stressed conditions; the plants growing in non-stressed conditions that were inoculated with PSB decreased in biomass. Under saline and alkaline stress, the bacteria were able to reduce the soil pH and in turn, enhance the availability of phosphorus, nitrate, and potassium. In the absence of these stressed conditions, the bacteria were very weak at solubilizing phosphate. Interestingly, the study also found that the soil microbial communities were altered in the stressed soils inoculated with PSB, due to the change in pH and salinity after the phosphate-solubilization. The decreases in pH and salinity caused certain microorganisms to be affected because of their sensitivities to certain conditions (Sun et al. 2024).
This research mainly diverts attention to S. suaeda restoration in East Asia and Australasia, but the findings can easily be applied to any areas of the world struggling with high salinity and alkaline soil. Soil health is an extremely important topic that most people should be educated on, especially those in agriculture. Biological solutions in soil management helps promote sustainable land use and soil remediation instead of land degradation (Sun et al. 2024).
Guo J, Zhou Y, Guo H, Min W. 2021. Saline and alkaline stresses alter soil properties and composition and structure of gene-based nitrifier and denitrifier communities in a calcareous desert soil. BMC Microbiology. 21:246. https://doi.org/10.1186/s12866-021-02313-z.
Iftikhar A, Farooq R, Akhtar M, Khalid H, Hussain N, Ali Q, Saif ul Malook, Ali D. 2024. Ecological and sustainable implications of phosphorous-solubilizing microorganisms in soil. Discov Appl Sci. 6(2). https://doi.org/10.1007/s42452-024-05683-x.
Song Y, Liu J, Wang J, Liu F. 2021. Growth, Stoichiometry, and Palatability of Suaeda salsa From Different Habitats Are Demonstrated by Differentially Expressed Proteins and Their Enriched Pathways. Front Plant Sci. 12. https://doi.org/10.3389/fpls.2021.733882
Sun X, Wang W, Yi S, Zheng F, Zhang Z, Alharbi SA, Ekaterina Filimonenko, Wang Z, Yakov Kuzyakov. 2024. Microbial composition in saline and alkaline soils regulates plant growth with P-solubilizing bacteria. Appl Soil Ecol. 203:105653–105653. https://doi.org/10.1016/j.apsoil.2024.105653
No comments:
Post a Comment