Assessment of a Differentiated Microbiologically Rich Compost on Soil Quality in Cereal-Legume Rotations

Long-term and unbalanced use of inorganic fertilizers has degraded soil quality in many areas. Organic amendments such as composts and legume rotations may provide a sustainable alternative, but systematic evaluations of compost types under different cropping systems remain limited. This study examined the effects of composts produced by different techniques on soil quality-related properties in a field experiment conducted on calcareous soil in Tigray, Northern Ethiopia, under two cropping systems: faba bean (Vicia faba L.) wheat (Triticum aestivum L.) rotation and continuous wheat. The experiment consisted of eight treatments: no fertilizer, mineral fertilizer (NPSZ), traditional compost, vermicompost, and compost with effective microorganisms (EM), as well as a combination of each compost with mineral fertilizer. Application of compost with effective microorganisms and vermicompost in this study improved soil physical, chemical, and biological indicators, by increasing the percentage of macroaggregates, total nitrogen, available phosphorus, cation exchange capacity, labile carbon, microbial biomass carbon, and soil respiration; and decreasing the percentage of microaggregates, bulk density and pH compared to traditional compost at the same rate of nitrogen application. The combined application of EM compost or vermicompost with mineral fertilizer, respectively, improved physical, chemical, and biological indicators compared to compost or mineral fertilizer alone at the same level of nitrogen fertilization. Furthermore, soil quality indicators were improved by rotation with faba bean compared to continuous wheat.