Effect of Marine Microorganisms on Limestone as an Approach for Calcareous Soil

Calcareous soils generally have low levels of organic matter and nitrogen; they require modification to promote their support for agriculture production. Calcareous soils are commonly found in important agricultural areas throughout the world, mainly around the Mediterranean, America and Australia. In this study, we the isolated and identified different groups of microorganisms, from a product made from seaweed, in relation to their soil improvement properties. The objective was to use these microorganisms for the solubilization of specific soil elements and reduce their accumulation as a result of overfertilization. The isolated microorganisms were grown in specific culture media and were applied on limestone to determine their effect on mobility of Ca, Mg and K. Also, changes in soil properties such as pH, texture and density were evaluated. This study demonstrated that the treatments applied were able to modify the solubility of Ca, Mg and K, increasing it, in some cases, up to 3500%. In addition, an increase of organic matter close to 200% was observed. Both the group of molds and yeasts, and the group of nitrogen-fixing microorganisms, modified the proportion of sand, silt and clay in the treated limestone. These results open possibilities for the widespread use of marine microorganisms on a large scale in the agricultural sector, since they improve the nutrient availability present in the soil.