SOIL & WATER

In the first phase of the project, sustainable land management interventions were deployed to help restore land and water resources in the Gumara-Maksegnit watershed. Soil and stone bunds and terraces were effective in preventing soil and water erosion.  

Assessing runoff and soil erosion

An important achievement of the project’s first phase was the installation of a monitoring system to track the effect of soil and water conservation measures (SWC). Meteorological data were provided by an automatic weather station and three rain gauges located respectively at the outlet of the main watershed and at the outlets of two experimental sub-catchments, one treated with SWC and the other untreated. At the three outlets runoff measurement and sediment sampling devices were also installed. The monitoring system provided data for tracking and modeling the effect of SWC measures on soil erosion and hydrology.

As an example, in 2011 about 21% of rainfall left the watershed, and for the whole watershed, the amount of sediment lost ranged from 2.9 to 27.6 t ha-1 per year. Soil and water conservation measures in one sub-catchment reduced sediment loss by 44%.

Monitoring runoff and soil erosion 
Monitoring runoff and soil erosion

The project team also collected data on soil loss and surface runoff, soil bulk density, soil texture, soil moisture content, and saturated hydraulic conductivity from fields with stone bunds and fields with no bunds. The data were analyzed to assess the:

·         Effectiveness of graded stone bunds in preventing soil erosion;

·         Spatial distribution and changes in soil properties as a result of SWC measures;

·         Effect of stone bunds on soil water content; and

·         Degree of gully erosion.

Monitoring soil erosion in the Gumara-Maksegnit watershed
Monitoring soil erosion in the Gumara-Maksegnit watershed

Harvesting rainwater for supplemental irrigation

Rainwater harvesting is an affordable way for farmers to cope with droughts as it makes water available for supplemental irrigation during dry spells. Groups of farmers built five ponds to harvest rainwater and lined them with geo-membrane material. Farmers were able to use this water for supplemental irrigation and to test several adapted crops.

Harvesting rainwater in the Gumara-Maksegnit watershed
Harvesting rainwater in the Gumara-Maksegnit watershed

Drip irrigation supplies water to the base of the crops and dramatically reduces the amount of water needed. Pepper, cabbage, Swiss chard, and carrot grown in field experiments that combined drip irrigation and applications of nitrogen fertilizer boosted yields. As an example, pepper receiving 1/3 and 2/3 of the full water requirement, and fertilized with 50 kg/ha nitrogen (N), produced 49.7% to 175.2% more green pods than rainfed pepper.