Effect of vermicompost on the biological properties of a saline-sodic soil in a semi-arid region of Venezuela

Chemical degradation of soils are widely distributed in the world, and their recovery can be based on application of amendments. The objective of this research was to evaluate the effect of vermicompost on the biological properties of a saline-sodic soil in the locality El Cebollal, in Coro, Venezuela. An experiment was performed to compare different doses of vermicompost using the following four treatments: (T1) a control, without vermicompost; (T2) 1 % vermicompost; (T3) 5 % vermicompost, and (T4) 10 % vermicompost. An incubation period of 28 days was applied, with measurements at 7, 14, 21, and 28 days. In each date the organic carbon (OC), microbial biomass carbon (MBC), urease activity (UA), and the index of available carbon (MBC/OC * 100) were evaluated. The OC increased in all vermicompost treatments, with the highest values in T4 (6.7 g.kg(-1)) and the lowest in the control (2.5 g.kg(-1)). Likewise, the MBC resulted in a significant increase, being the highest also in T4 (612.5 mu g.g(-1)) and the lowest in the control (36.4 mu g.g(-1)). The UA increased significantly with the addition of vermicompost. After 28 days of incubation we found values for NH4+ of 67.8 mg.g(-1) in T4, which represents a six-fold increase as compared to the control treatment. The addition of vermicompost proved to be a good strategy for biological recovery of saline-sodic soils.