The farm pond is an underground runoff storage reservoir – a truncated rectangular pyramid shaped – lined with a 0.8mm thick ultra-violet resistant plastic sheet (to control seepage losses), and roofed either with iron sheet or shade net (to reduce evaporation, contamination, and risk of drowning). The farm pond harvests surface runoff and direct precipitation (either from iron sheet roof or through the 80% shade net roof). For a 50m3, the top and bottom dimensions are 8m by 6m, and 4m by 2m respectively, while the depth is 2m – with 1:1 side slope. Different dimensions for the farm pond can be adopted, for example 72 or 90m3 storage capacity, are being promoted for primary schools – vegetable production, establishment of tree seedling nurseries, and supplementary irrigation of tree and fruit seedlings.
To reduce siltation and improve water quality a simple masonry double chamber (each of 0.6m by 0.6m by 0.6m) silt trap which, allows silt to settles as the water enters into the farm pond, is incorporated. Surface runoff collects a lot of silt especially if the catchment is bare e.g. drainage from roads and foot paths. The silt trap is design to act both as an inlet of the farm pond as well as the overflow. There are two inlets fitted with 4-inch PVC pipes and screen filters to prevent floating debris from entering the farm pond.
The farm ponds are roofed either with iron sheets or shade nets to (a) reduce the water losses through evaporation, (b) control mosquito breeding, (c) to reduce risk of children and domestic animals drowning, and (d) protect the dam liner from malicious damage and deterioration from direct exposure to sunlight. The original design adopted iron sheet roofing, but shade net roofing has been adopted to reduce cost, and environmental degradation. On cost-effectiveness, the shade net roofing is about 50% cheaper than iron sheets due to low unit cost (per m2) and lighter roofing structure. However, due to environmental concern and termites attack on wooden roofing structures, KRA designed a metallic roofing structure for shade net roofs, which has further reduced the cost of roofing to about 40% of the total cost (i.e. USD 900) of a 50m3 farm pond. The shade net roofed farm ponds have also been adopted for fish farming by some innovative farmers and the results are encouraging – enhancing multiple uses.
Low-head Drip Irrigation System
Drip irrigation has been adopted, as a one of the complementary technologies, to improve water management – increase water use efficiency and productivity - ensuring water availability over the entire vegetable growing period. KRA in partnership with WAREM Consultants Ltd. has been promoting low-cost low-head drip irrigation as a complementary technology for RHM system. The WAREM’s “dream drip kit” irrigation systems are tailor-made to suit different farmers’ preference, crop specifications and land layout. They are farmer-friendly in terms of cost-effectiveness, O&M, and can be easily repaired since they are assembled from locally available components. Different sizes of locally assembled low-head drip irrigation systems can be used for a 50m3 farm pond, ranging from 20-litre bucket and 50-litre jerrican kits to 230-litre mini-tank kit (which is the most optimal in terms of water availability). Larger sizes up to one-acre units are also available.
For the 50m3 farm pond, a 230-litre mini-tank drip irrigation kit, which consists of 16-20 laterals of 15m long, covering an area of 250-300m2, and 1,000 plants spaced at 30cm along the drip line emitters, is appropriate. The vegetable garden (about 16m by 16m) is prepared by double digging and raising the planting beds up to 10-15cm at predetermined spacing – dictated by the row spacing of the drip irrigation system. The simple wooden stand for water tank is constructed and the tank placed at 1.0m – height predetermined by the downpipe. The downpipe is fitted with a PE gate valve and screen filter, and connected to the PE header connector with in-built barb connectors for fixing the drip laterals.
The water is pumped from the farm pond into the drip system using a simple hand-pump – Hip pump from KickStart – which is preferred due to its ease of operation and storage – it is light and can easily be carried for safe keeping after use.Water from the raised tank flows by gravity through a gate valve into the vegetables planted along the drip lines at row spacing pre-determined by the emitter spacing. The result is a more efficient method of irrigating vegetables as the water drips directly to the plant root zone maximizing water productivity by reducing water wastage through evaporation and deep percolation. The drip irrigation system supply water twice a day – in the morning and in the evening – when evaporation losses are minimal. Therefore, the 50m3 farm pond is adequate for a 230-litre mini-tank micro-irrigation system (i.e. 46m3 seasonal water requirement considering 100-days growing period for most vegetables).
Low-cost Greenhouses for Vegetable Production
With availability of water in the farm ponds, innovative farmers has adopted greenhouse for production of tomatoes and capsicum. In the dry areas, tomatoes are mainly grown under greenhouse to reduce pest infestation and frost. Some of the farmers learnt from the neighbouring large-scale horticultural producers (e.g. Homegrown) and scaled down greenhouse sizes to 8m by 16m, which is constructed using locally available materials for the framework. While others learnt from the exchange visits, and adopted the greenhouses. This initiative has greatly intensified crop and water productivity, and it is amazing that in only one season, a farmer can recover the total investment cost – RHM systems (USD 900) and greenhouse (USD 800) – compared with a total seasonal revenue of USD 2,000 - 2,500.
In-situ soil moisture conservation for crops and fruits production
In the semi-arid environments, establishment of fruits is normally hampered by seasonal soil moisture stress. To address this problem, soil and water conservation component is integrated especially planting pits – called by many local names (e.g. zai pits, tumbukiza pits, matengo pits, etc.), which are dug along the contours especially ditches/ridges for terraces. The planting pits (0.6m by 0.6m by 0.6m), which are spaced at least 2-6m, are filled with a mixture of top soil, composite and farm yard manure. A fruit seedling (e.g. paw paw, mango, banana, citrus, passion, etc.) are planted. The pits collect and conserve moisture which support fruit seedlings establishment.
Establishment of tree/vegetable seedling nurseries
Sources of seedlings for vegetables and trees including fruits are rare in the semi-arid environments, and hence promotion of drip irrigation, fruit production and agro-forestry would be futile without a source of seedlings. Therefore the package include establishment of communal seedling nurseries or improving existing privately owned ones – if it is acceptable to the community – private nurseries are more sustainable as they are driven by income generation. For communal nurseries women/youth groups are encouraged to take charge as an income generating venture. This component is implemented in collaboration with the Ministry of Agriculture, Forestry departments and private sector. The common vegetable species (e.g. kale, spinach, cabbages, carrots, onions, and capsicum), fruits varieties (e.g. paw paw, mango, orange, passion, avocado, etc.)and appropriate agro-forestry trees are included. Water from the farm ponds is used to enhance seedlings survival rate after transplanting.
Some of our successfully accomplished projects include:-
Mrs. Gathoni - Ndeiya, Kiambu County
Mrs. Gathoni, another beneficiary from Kiambu county, shares her experiences, “I am very proud to be associated with KRA, in the dry season, I was able to harvest tomatoes, sukuma wiki and spinach, that is a very rare occurrence in this region. The vegetables I harvested were both for my consumption and also for sell. To me increased household income is a benefit, for my day to day needs. The farm pond has created awareness in the community, I keep getting neighbours asking about the technology and I happily share what this entails.”
Mr. Charles Kuria - Umande Project
The chairman Umande project Mr. Charles Kuira had this to say, “We have worked with KRA for some time now, since the entrance of KRA our lives have been transformed we are commercial farmers and we farm throughout the year. We are grateful for the total life transformation and we can only hope that or lives continue changing. To all members out there, whatever KRA teaches has been tried and tested and it works, take it and transform your life. It is joy to be self-employed and to have food in plenty throughout the calendar year.