Disconnecting sediment transfer pathways on agricultural landscapes in the hot-humid lowlands of Northwest Ethiopia

Sediment transfer pathway disconnecting (STPD) practices break the length of sediment transfer pathways (STPs) and reduce agricultural landscapes connectivity or continuity. Soil and water conservation practices implemented on agricultural landscapes are STPD practices by trapping sediments and forming sediment ridge lines. Although STPD practices have been implemented in the hot-humid, lowlands of northwest Ethiopia for the past four to five decades, their impact in breaking the continuity of STPs and slope length, trapping sediment and forming sediment ridge lines, improving soil properties and thus grain yield, has not been investigated in detail.

A field experiment was designed consisting of four treatments with three replications: (i) agricultural landscapes disconnected with fanya juu ridge; (ii) agricultural landscapes disconnected with stone faced soil bund; (iii) agricultural landscapes disconnected with fanya juu ridge combined with vetiver grass; and (iv) agricultural landscapes without any treatment as a control. Data on trapped sediment, change in slope gradient, soil physical properties and maize grain yield were collected and analyzed.

STPD practices trapped large amount of sediment, formed sediment ridge lines, broke STPs and reduced landscape connectivity by ~ 3%. As a result, the disconnected agricultural landscapes improved soil properties and thus increased maize grain yield by 21%.

STPD practices reduced landscape connectivity by forming sediment ridge lines and a series of bench terraces. Hence, governmental and non-governmental organization could consider such STPD practices as landscape disconnecting methods to reduce landscape continuity, slope length and gradient, surface runoff concentration, and thus sediment transport and soil erosion.