Influence of Long-Term Permanent Raised Beds and Contour Furrowing on
Soil Health in Conservation Agriculture Based Systems in Tigray Region,
Ethiopia
Abstract
Conservation agriculture (CA) systems represent a set of three soil
management principles that include minimal soil disturbance, permanent
soil cover and crop rotations whereas the CA-based systems in this study
add the bed and furrow tillage structures as integral elements of CA.
This study aimed at investigating the long-term (2005-2013) influence of
CA-based systems on soil health and crop productivity in northern
Ethiopia. The treatments include two types of CA-based systems
(permanent raised bed PRB and contour furrowing CF) and conventional
tillage (CT). The experimental layout was arranged in a randomized
complete block design. Soil samples were collected at 0-10 cm soil depth
to assess soil health. Wheat root samples were used to measure
arbuscular mycorrhizal fungi (AMF) colonization percentage using grid
line intersect method. Piecewise structural equation modeling (PSEM) was
used to understand linkages between management practices, soil health
and crop productivity. Higher soil microbial biomass carbon (SMBC), AMF
spore abundance and root colonization were recorded in PRB followed by
CF as compared to CT (P < 0.05). Carbon sequestration rate,
nutrient availability, plant available water capacity and air capacity
were significantly higher in PRB and CF compared to CT. Outputs of the
PSEM highlighted two pathways in which CA-based systems contributed to
improved productivity: (1) via higher density of bacteria and improved
hydraulic conductivity, and (2) via higher density of fungi and increase
soil organic carbon content in the topsoil. The study concludes that
CA-based systems have the potential to improve crop productivity through
improved soil health.