In drip irrigation, water is conveyed under pressure through a pipe system to the field where it drips slowly into the soil through ‘emitters’ which are located next to the plant, only wetting the immediate root zone. It is thus a very water efficient irrigation system compared with others. Water savings result from reductions in deep percolation, in surface runoff and in direct evaporation from the soil surface. The small amount of water used also reduces weed growth and limits the leaching of plant nutrients. Large scale commercial drip irrigation systems have a high ‘start up’ cost. In response to this, simple low-cost gravity fed drip irrigation systems more appropriate for small-scale farmers have been widely promoted in Africa and Asia of (Belder et al. 2007 2, IWMI 2013 3). Such systems typically use raised barrels or buckets placed between one and two meters above ground level to provide the height required to distribute the water through bamboo or PVC tubes (see SSWM link below). With proper management, plant nutrients can be added to the irrigation water before conveyance, known as ‘fertigation,’ enabling very precise timing, placement and availability of nutrients for plant uptake.
Relationship to CSA
When successfully managed, low-cost drip irrigation can provide substantial increases in crop and tree productivity for small-scale farmers. In addition, in regions where current or projected water scarcity is likely to impact farmers’ welfare, resilience is enhanced through the high water use efficiency of drip irrigation and the water saved compared with other systems.
Impacts and lessons learned
Where wide-scale promotion of low-cost drip irrigation systems has taken place, subsequent impact studies have shown a very high rate of ‘disadoption’ after one or two years (Belder et al. 2007 2, IWMI, 2013 3). There were a range of reasons farmers discontinued using the system, but the fundamental constraint has been that the promotion of drip irrigation was not properly supported by continued capacity building and advice from extension services. Where subsequent efforts were made to train farmers, as was the case in Southern India, immediate and positive water saving and production increases were observed (IWMI 2013). 3
Stauffer B. 2012. Drip Irrigation. Basel, Switzerland: Sustainable Sanitation and Water Management (SSWM).http://www.sswm.info/category/implementation-tools/water-use/hardware/optimisation-water-use-agriculture/drip-irrigation Drip irrigation is a technique in which water flows through a filter into special drip pipes, with emitters located at different spacing. Water is distributed through the emitters directly into the soil near the roots through a special slow-release device. If the drip irrigation system is properly designed, installed, and managed, drip irrigation may help achieve water conservation by reducing evaporation and deep drainage. Compared to other types of irrigation systems such as flood or overhead sprinklers, water can be more precisely applied to the plant roots. In addition, drip can eliminate many diseases that are spread through irrigation water. Drip irrigation is adaptable to any farmable slope and is suitable for most soils. In contrary to commercial drip irrigation, simple self-made systems are cheap and effective.
Belder P, Rohrbach D, Twomlow S, Senzanje A. 2007. Can drip irrigation improve the livelihoods of smallholders? Lessons learned from Zimbabwe. Global Theme on Agroecosystems Report no. 33. Bulawayo, Zimbabwe: ICRISAT.http://ejournal.icrisat.org/volume5/aes/aes3.pdf It is estimated that one third of the rural population in sub-Saharan Africa is malnourished. Strategiesto mitigate the effects of poor agricultural productivity and drought involve developing the continent’sunexploited irrigation potential. One intervention, based on successes from Asia, which shows promisein improving household nutrition in the rural areas through better vegetable production, is small-scaledrip irrigation. This system is said to save water and labor. Since 2002, some 70,000 low-cost, low-headdrip irrigation kits have been distributed through humanitarian relief initiatives in the rural areas ofZimbabwe.In the dry season of 2006, a country-wide survey was undertaken in Zimbabwe to determine the impactsof drip kits that had been delivered to needy households. Survey results showed that disadoption of dripkits occurred as a function of time and after 3 years only 16% of the kits were still being used. Reasons fordisadoption included lack of water, lack of understanding of the drip kit concept, and, more importantly,a lack of technical support and follow up by the non-governmental organizations that distributed the kitsand the extension services. A cost-effectiveness analysis showed that drip kits are more cost-effectivethan traditional hand watering only when potential water savings are achieved. However, this was hardlyever the case due to the beneficiaries’ lack of knowledge on crop water requirements when using the kitsand a perception that the soil surface should be wet.Consequently, the study concluded that a relatively complex technology such as drip kits should notbe part of short-term relief programs, but should instead be embedded in long-term developmentalprograms that involve both the public and private sector. This will ensure that appropriate technicalsupport is provided in terms of crop management and the development of supply chains for spare partsand additional kits.
IWMI. 2013. Making a difference drop by drop. Success Stories Issue 18. Colombo, Sri Lanka: IWMI.http://www.iwmi.cgiar.org/Publications/Success_Stories/PDF/2013/Issue_18-Making_a_difference_drop_by_drop.pdf In the Coimbatore District of Tamil Nadu, India, over 90% of farmers who had been encouraged to invest in drip irrigation systems did not know how to use them properly. Increases in crop productivity were disappointing. A capacity building initiative, led by the IWMI-Tata Water Policy Research Program and local partners, trained farmers in all aspects of drip irrigation. This led to water savings and yield increases of up to 40% for some crops.