Although phosphorus (P) is one of the most important macronutrients required by plants, the availability of soluble forms of P in soil is limited. Not only are chemical P fertilizers expensive, but they also have a negative impact on the environment, causing eutrophication and soil fertility depletion. Therefore, ecologically and economically sustainable alternatives are urgently needed.
Phosphate solubilizing microbes (PSMs) are a group of beneficial microorganisms capable of hydrolyzing organic and inorganic insoluble phosphorus compounds to soluble P forms that can easily be assimilated by plants.
In an article published in International Journal of Agronomy, Girmay Kalayu, from Aksum University in Ethiopia, evaluated the potential of using PSMs in crop production as biofertilizers by reviewing recent studies focused on the effects of PSMs on plant growth.
The findings suggest that by lowering soil pH, chelation, and mineralization, PSMs can effectively convert insoluble P compounds to plant-available P forms, resulting in better plant growth, crop yield, and quality. It is also reported that PSMs can help plants to absorb phosphorus from a wider area by developing an extended network around the root system and that they can act as a biocontrol agent against plant pathogens via production of antibiotics, hydrogen cyanate and antifungal metabolites.
Although PSMs have demonstrated ecological and economical advantages over chemical P fertilizers, the application of PSMs in agriculture is not straightforward because different varieties of PSMs have different impacts on different crops. For example, inoculation with Azospirillum spp. showed increased yield in maize, sorghum, and wheat, while inoculation with Bacillus spp. revealed increased yield in peanut, potato, sorghum, and wheat.
The author concludes that PSMs represent promising biofertilizers in sustainable agriculture, but more field trials are necessary to determine the effectiveness of PSMs and how to best utilize them on a large scale.
This blog post is distributed under the Creative Commons Attribution License (CC-BY). Illustration by David Jury.