High pH values and high calcium carbonate content in calcareous soils are the major chemical problems, which have a significant impact on the availability of nutrients, especially phosphorus, nitrogen and micronutrients. Due to the increasing population and soil fertility declines, there is currently a large gap between agricultural production and food demand. Therefore, it is necessary to address the limitations of calcium carbonate-rich soils for crop production by developing a new strategy. IpH values and high calcium carbonate content in calcareous soils are the major chemical problems, which have a significant impact on the availability of nutrients, especially phosphorus, nitrogen and micronutrients. Due to the increasing population and soil fertility declines, there is currently a large gap between agricultural production and food demand. Therefore, it is necessary to address the limitations of calcium carbonate-rich soils for crop production by developing a new strategy. In this work, a calcareous soil conditioner for reducing high carbonate content based on a composite material consisting of bentonite clay impregnated with humate-capped nanosulfur was synthesized using the Raffo process. The innovative composite material with uneven surface and numerous embedded smooth nanosulfur spheres and a high number of active sites can be used efficiently as a calcareous soil conditioner. This soil conditioner effectively improves soil health and quality and maintains it by reducing high levels of calcium carbonate. The optimal amount was 500 kg ha-1 composite, which reduced the soil pH by 0.59 units and the active carbonate content by 57%. Fourier transform infrared spectra of treated soil with the optimal amount showed that the intensity of the absorption bands corresponding to the active carbonate groups and calcite mineral was reduced. Interestingly, powder X-ray diffractometer matching phase analysis revealed that a new peak appeared due to the new formation of sulfate-carbonate coprecipitates or the so-called rapidcreekite mineral, which forms under limited conditions with high levels of dissolved sulfate compared to carbonate. Although the composite optimal rate provided more favourable soil conditions, the study recommends that the synthesis composite be further evaluated in future field trials with different calcareous soil conditions and crops.