Testing the effect of a microbial-based soil amendment on soil aggregate stability and erodibility

End date
July 31, 2016
Project coordinator
Mponda Jumanne Malozo
Project code
mbsu14-2M1 BSU
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Contact person
Mponda Jumanne Malozo

Soil degradation problem in the world has been reported to have increased significantly in the past 50 years, with nearly 2 billion ha of land are estimated to have been degraded of which 22% includes arable land. Soil erosion by water is the most common soil degradation problem in almost every country under varying climate, topography and land use practices. The impact of soil erosion often results into the reduction of land or soil productivity, by wash away of nutrient on the top rich soil or by causing water quality problem through deposition of eroded sediment and nutrients into water bodies. Practices such as increase of soil organic matter content, enhancing aggregate stability, macroporosity, infiltration capacity and reduce rainfall erosivity have been used to control soil degradation induced by water erosion. In this study a microbial-based soil amendment (MICRO) was tested to observe its impact on improving aggregates stability and reducing soil particle erodibility under rainfall-runoff simulation. The treatment impact was compared to that of microbial agent carrier solution (CAR) and commercial gypsum (GYPS) with calcium sulfate dihydrate as soil amendment. The soil samples that were used was collected from Mwanza region in northern Tanzania and from Denmark at Flakkebjerg and Risø sites in Zealand. These soils had known history of structural problems. Water aggregate stability and clay dispersibility test were conducted at macro- and microaggregate level and also soil tensile strength test. The test results show that the microbial-based soil amendment had significant impact on increasing water aggregate stability, tensile strength and reduced soil erodible particles on the tested soils. The MICRO treatment was found to have small impact on reducing soil clay dispersibility compared to CAR and GYPS treatment. Compared to the CAR treatment, MICRO treatment also had less impact in increasing water stable aggregates on Flakkebjerg and Tanzania soil. The impact of MICRO treatment was generally more pronounced on sandier soil with low organic matter, silt and clay content at macroaggregate level.