What Do Data on Dry Bulk Density (BD) And Porosity (P) Tell About The Quality of Soils in the Mumias Sugar Zone, Western Kenya?

A study conducted from 2009-2011 on soils in the Mumias sugar zone of western Kenya involved the determination of dry bulk density (BD), moisture content (MC) and porosity (P) in 31 sites. Bulk density varied from site to site ranging from 1.46 g/cm3 to 1.81 g/ cm3 ; BD was generally higher in the 30-60 cm layer than in the 0-30 cm layer. Soil moisture content varied from one sampling site to another ranging from 17.8 – 37.5 %. Soils were drier in the top 0-30 cm layer than in the lower 30-60 cm layer. Average porosity ranged from 31.9% – 44.5%. Porosity, being inversely related to BD was highest in areas with least BD. Porosity was generally higher in the top soil 0-30 cm layer than in the lower 30-60 cm soil layer. This study demonstrated that the sugarcane production practices in Mumias had led to serious deterioration of two soil physical quality parameters the bulk density (BD) and porosity which may have contributed to sugarcane yield decline over the years. The enhancement of minimum tillage practices, green cane harvesting, trash blanketing, good soil conservation practices and avoidance of heavy machinery on fields in the wet on both the miller owned farm and among smallholder farmers is recommended.