Long-term effects of tillage, sub-soiling, and profile strata on properties of a Vitric Andosol in the Kenyan highlands
Ngetich, K. F.
MetadataShow full item record
Tillage alters the structure and composition of soil aggregates affecting infiltration rate (IR) and hydraulic conductivity (K). This study investigated the long-term effects of conventional, minimum, and no-tillage with or without subsoiling on aggregate stability, soil organic carbon (SOC), bulk density, IR, and K of a stratified Vitric Andosol in Kenyan highlands. The experiment was laid out in a spilt-split plot design with three replicates. Stepwise profiles were dug in order to expose the soil layers at 0 to 30, 30 to 60, and 60 to 90 cm depths. Soil bulk density was 6% lower in the minimum tilled and 12% lower in the conventionally tilled plots that were subsoiled compared to treatments with no subsoiling and tillage. Subsoiled treatments also increased sequestration of SOC by 20% in the 30 to 60 cm layer. Conventional tillage, however, decreased aggregate stability by 32% compared to no-tillage treatments. Subsoiling in combination with minimum tillage decreased IR by 25% but increased IR about three-fold in conventionally tilled plots. Hydraulic conductivity in the 60 to 90 cm layer was lowest, which constrained water movement in this stratified soil.