Integrated organic–inorganic amendments enhance sorghum productivity and soil fertility in degraded ultisols

Abstract This study aimed to address the issue of land degradation in Ultisol soils by investigating the impact of various amendments on the growth of Sorghum (Sorghum bicolor L. Moench Accession KS). Specifically, the study explored the effects of compost, NPK fertilizer, mycorrhizal propagules, and lime on soil nutrient levels, microbial communities, and Sorghum growth. The experimentation involved 16 different treatments, combining compost, NPK fertilizer, mycorrhizal propagules, and lime in Ultisol soil. The plants were grown in pots under natural trophic greenhouse conditions. After 9 weeks, the Sorghum plants were harvested, and various plants and soil parameters were analyzed. The combination of compost + NPK fertilizer + mycorrhizae + lime significantly increased dry stover growth by 1679% and mycorrhizal colonization by 271% compared to the unfertilized/unamended control in toxic ultisol soil. The introduced amendments positively influenced soil microbial communities, with the highest fluorescein diacetate (FDA) activity and phosphatase enzyme levels observed under this combined treatment. The introduction of NPK and lime showed a positive association between alkaline phosphatase activity and soil phosphate concentration. Additionally, the Sorghum plants exhibited increased sugar content, organic matter, number of leaves, and available phosphorus when compost, lime, and mycorrhizal propagules were introduced. The study demonstrates that incorporating a combination of organic and inorganic amendments is essential for enhancing Sorghum growth and promoting soil health in Ultisol soils. The findings highlight the potential of these amendments to mitigate land degradation issues in Ultisol soils and suggest practical strategies for sustainable agriculture in similar soil types.