Description
Similar names: Retention trenches, infiltration trenches
The name Fanya chini means “throw it downwards” in Kiswahili. It consists of trenches and earthen ridges facing downslope. This intervention aims to reduce soil erosion by breaking down long slopes into smaller sections. Thus, the speed of runoff will decrease, and water can infiltrate into the soil between the bunds. This will result in a reduction of nutrient leaching and increased water availability for crops. Fanya chini is common in areas with 300-600 mm of annual rainfall on 1-25% slopes. It is suitable for all types of relatively permeable soils (e.g. alluvial, red, laterite, brown, and shallow and medium black soil). Still, it doesn’t work very well with clayey soils or vertisols as these are not permeable.
One of the main benefits of Fanya chini is that it limits soil erosion from water runoff, and simultaneously improves water retention in the soil and increases water availability for crops. Furthermore, an increase in yield is observed, as well as improved soil fertility.
PRE-CONDITIONS FOR IMPLEMENTATION
- As with all earth structures, maintenance is fundamental. The structures should be reinforced every year to prevent breakages. If combined with grass strips, the grass strips require trimming to keep them dense and low, preventing them from burning during the dry season.
- A small reduction in area used for agricultural purposes will be necessary for the construction of the trenches. However, this can be limited by integrating vegetative measures, such as growing grasses or trees used for fodder between the trenches.
- Controlled grazing: grazing should be well managed and controlled so as not to damage the structures.
METHOD OF APPLICATION
Material required
- Hoe (Jembe) or shovel
- Pickaxe (for hard soils)
- Draft animals or excavating machinery for more efficient excavation
- Instrument to measure the slope: some examples of tools you can use include an Abney level, a line level, or a spirit level.
- To measure the contour line, here are some examples of tools that could be used:
- a string line level or spirit level instrument, hose pipe half filled with water, bottle of water half filled with water, A-frame level. You can also ask a person who is acquainted with measuring levels (such as a masonry worker) which tool they use, and you can use the same approach to measure your land.
Steps of implementation
- Excavation of trenches: Dig trenches measuring 50-60 cm deep and 60 cm wide. These trenches serve as the foundation for the contour bunds and are essential for water management.
- Placement of excavated Soil: Place the excavated soil on the lower side of the contour trenches, facing downslope. This practice distinguishes Fanya chini from Fanya juu, where the excavated soil is relocated upslope.
- Formation of bunds: Construct bunds using the excavated soil. The bunds run along the contour lines and act as barriers to control soil erosion and manage water flow.
- Creation of microcatchments: The presence of the bunds creates microcatchments that concentrate runoff from the upslope land. This concentration of water is essential for effective water harvesting and management.
- Integration with tree planting: Utilize contour bunds in conjunction with tree planting interventions. The bunds provide an ideal platform for water harvesting, making them compatible with various tree species.
- Crop cultivation: Implement contour bunds for crop cultivation, including both annual crops like maize, teff, and fava beans, and water-demanding crops like bananas, fruits, and vegetables. Planting locations are selected based on runoff collection areas, typically above or below the bunds.
By following these implementation steps, the Fanya chini technique can effectively manage water resources, control soil erosion, and support diverse agricultural activities in the landscape.
A very good step-by-step guide is provided by Justdiggit; you can find instructions here and in this video.
BENEFITS
This intervention contributes to:
COSTS
Estimation of costs and benefits of intervention (2011)
| Implementation costs | US $8/ha |
| Maintenance costs | US $8/ha |
CASE STUDIES
1. Fanya chini implementation in Tanzania
Description
In Tanzania, the implementation of Fanya Chini terraces has proven to be successful in enhancing agricultural productivity and mitigating the effects of climate change. A total of 45 terraces were constructed, spanning a length of 2,670 meters across individual farms and institutions. These terraces were planted with pineapples to stabilize them and maximize their effectiveness. Farmers were encouraged to engage in mixed cropping, combining crops such as maize and vegetables in the fields. This practice, along with the retention of water in the contour ridges, resulted in significantly higher yields compared to conventional farming methods. Testimonials from farmers highlight the positive impact of Fanya Chini contour farming. Mwinyimvua Nassoro, for instance, reported a remarkable increase in maize yield without the use of fertilizers, thanks to water retention in his fields. Similarly, a young boy expressed his intention to adopt Fanya Chini farming in the future after witnessing its benefits in his father's fields. Overall, Fanya Chini has emerged as an effective strategy for conserving soil and water, improving crop yields, and empowering farmers to adapt to
FIND OUT MORE
Guides
- Good instructions on how to follow the contour line and measure the slope of the land can be found here.
