Seasonally dry riverbeds are an under-utilized resource that can be used for sustainable vegetable production. In the Indian subcontinent, climate change-induced floods and the encroachment of riverbeds are silting over arable land and increasing the area of sandy riverbeds. In the Terai of Nepal, landless, land-poor, and severely flood-affected farmers lease the riverbeds for cultivation in the post-monsoon dry season (November to May). Cucurbitaceae (gourd) vegetables are produced for household consumption and market sale. By utilizing an under-exploited resource and enhancing farmers' production skills on marginal soils, leasehold riverbed vegetable farming increases marginal farmers' options for sustainably coping with the effects of climate change.
Dry season riverbed vegetable farming was introduced in the Terai by migrants from India. Unable to access arable land for agricultural production, these landless farmers cultivated the riverbeds, which run dry after the monsoon season, from November to May. Major riverbed crops are pumpkin, bottle and bitter gourds, cucumber, and watermelon.
Riverbed farming, as practiced in the Terai, is based on the formation of farmers' groups and a leasehold system to rent the riverbeds from the landowner. Since the riverbed plots are grouped together and usually located slightly away from the village, trust amongst farmers is key. The leasehold system is uniquely suited for production systems on dry riverbeds. By their very nature the rivers change course over time, rendering long-term investments in a specific part of the riverbed futile. Since no land ownership is required by practitioners, the leasehold system allows resource-poor farmers to access land suitable for agricultural production at a low initial investment cost.
Inhabitants of the Terai are confronting challenges to their food security that are emblematic of problems smallholders around the world face. Production pressure on arable land is increasing due to population growth and increasingly erratic hydrological cycles, caused by climate change.
Being a high-altitude ecosystem, the Himalayas are warming at a faster rate than the global average. Since all of the water in the Indian subcontinent comes from the Himalayas, their warming is strongly impacting regional hydrological systems. Due to glacial melting, rivers carry both more water and more sediment downstream, with twofold effects. First, the increased volume causes large movements of the riverbed from one wet season to another. Second, the increased water and sediment volume mean that the rivers that ran narrow and deep twenty years ago are now shallow and wide, continuously enlarging the areas of sandy riverbeds and contributing to the over-sedimentation of fertile fields. Climate change-induced extreme events such as flash floodsare occurring more frequently, and exacerbate the spread of riverbeds.
The warming of the Himalayas has already significantly impacted agricultural production in the Terai. Increasingly erratic weather patterns and regional hydrological systems mean that farmers in the Terai face higher risks from environmental shocks and larger pressure to adapt to producing on marginal lands. Riverbed farming can contribute to alleviating production pressure on arable land by sustainably maximizing the use of marginal land – dry riverbeds.
Suitable locations and initial considerations
Suitable locations for riverbed farming are usually located not more than 30 minutes on foot away from the village. The riverbed's sand should have a fine and small-grained texture. A groundwater table of less than 1 meter depth obviates the need for irrigation; however, both riverbeds and riverbanks may be cultivated. Riverbeds usually do not require irrigation after cropflowering, but bear higher risks of total crop loss due to environmental shocks such as floods. Riverbank cultivation decreases the risk of crop loss because of flash floods, but increases labor requirements by necessitating irrigation during the entire season.
Socially, a certain amount of community cohesion and trust are necessary to facilitate the farmer group's formation and its subsequent activities. Once the group has formed, a leader is elected to act as the group representative during the lease negotiation process. A Local Resource Person (LRP) is chosen from the group or allocated from a neighboring riverbed group, and trained as a riverbed extension specialist by external extension systems.
In the Terai, each farmer made an initial investment of US$ 37 to cultivate a 4 kattha (1,354m²) plot, which is large enough to support a family without having to hire outside help (US$ 275 per hectare). Initial investment costs include the cost of the lease and inputs (seeds, fertilizer) for one season.
Acting as a representative of the whole group, the group leader negotiates the lease with the owner of the riverbed. Leases are negotiated for an initial period of three years, with one-year extensions after that.
LRPs are a key element for disseminating technical know-how about riverbed farming. Based on training received, they disseminate initial information and technical know-how to riverbed farmers through group workshops. Throughout the crop season, they regularly provide extension services and further training in agricultural (like composting and seed storage) to farmers.
Riverbed plots are chosen by farmers, with plots perpendicular to the river's flow. This allows every farmer equal access to different types of soil needed for the different crops. Starting closest to the water's edge, crops are planted in rows oriented according to the prevailing wind. Short-rooted crops like cucumber and bitter gourd are planted close to the water; long-rooted bottle gourds, pumpkins, and watermelon are planted further in the back. To prevent crop damage by thieves or wild animals, a fence is erected around the perimeter of the plots. A shelter is built in the vicinity to serve as protection from the sun during the day, and to function as a look-out during the night.
Farmers choose either the pit or the ditch system when planting, depending on personal preferences and labor availability. For the pit system, pits are dug 1 m deep and 0.5 m apart and planted with multiple seeds, the weakest of which are thinned out. In the ditch system, a trench 1 m deep is dug along the row, with 2 m (cucumber, bitter gourd) to 3 m (watermelon, bottle gourd, pumpkin) space between rows. Seeds are planted spaced 0.5 m (cucumber, bitter gourd) to 1 m (watermelon, bottle gourd, pumpkin) apart in the ditch.
Irrigationis necessary for seedlings every 2 to 3 days if the soil does not contain enough moisture. However, if plants have groundwater within 1 m depth, no further irrigation is necessary after this. Mulching is used to conserve soil moisture, support branch distribution, protect from wind damage, and minimize weed growth. No tillage is necessary. Top-dressing or side-dressings are applied at a rate of 15 tons of farmyard manure, 22 kg of urea, 49 kg of DAP, and 22 kg of potash per hectare.
After harvest, crops are transported to local market centers for sale.
Outputs and outcomes
Riverbed farmers in the Terai produce an average of 16,500 kg of vegetables per hectare, per season, earning an average gross agricultural margin of almost US$ 2,500 per hectare (US$ 336 per household with 4 kattha).
Riverbed farming does not require irrigation, tillage, or energy inputs besides human labor, and generates zero waste that is not recycled on-farm. As smallholders generally use their resources as efficiently as possible, riverbed farmers use minimal amounts of chemical fertilizers and pesticides as they seek to lower production costs. Studies on the impacts of chemical usage on groundwater remain to be done; however, it is expected that due to the above reasons, groundwater pollution should be SMALL. Since the rivers change course every few years, requiring new pits or trenches to be dug, there is minimal danger of acidification of the soil. As crop vegetation and mulching cover the fine sand of the riverbeds, less wind erosion occurs so there is less dust in the air, helping to improve the local micro-climate. By anchoring the sand, the crops' root systems help structure the riverbed soil and increase its microbial activity.
Female farmers find riverbed farming attractive due to the plots' location close to the village. Female farmers fill multiple roles in the home and on the fields; the plots' proximity to the home allows them to efficiently multi-task between domestic and production duties.
Riverbed farmers report that the production technology is easy to learn. This is bolstered by observation of independent replication of cultivation in riverbeds by neighboring communities, which highlights both the ease of use and the low initial investment costs required.
In the Terai, riverbed farmers enhance their skills of production on marginal, sandy soils, especially through the workshops with LRPs. Considering the increasing spread of riverbeds in the Terai due to the effects of climate change in the Himalayas, learning production skills on these marginal soils increases marginal farmers' options for sustainably coping with the effects of climate change.
Opportunities and constraints
Leasehold riverbed farming is a low-environmental-impact, easy-to-learn, cost-effective technology allowing landless households to produce on unused marginal lands. Riverbed farming avoids possibly thorny land tenure issues: not only is it based on a leasehold system, but by their very nature the rivers change course over time, rendering long-term investments in a specific part of the riverbed futile. In the short term, riverbed farming may increase farmers' vulnerability to environmental shocks. In the medium and long term, it increases households' resilience and creates rural employment opportunities.
Riverbed farming could be part of a community-based adaptation strategy to the impacts of climate change. Riverbed farming offers opportunities for linkages to other community-based initiatives, such as Community Seed Banks (CSBs) and Participatory Plant (PPB) programs, for input procurement. Integration of other agroecological issues, such as agro-forestry and reforestation of the riverbanks, is an opportunity to both.
In the Terai, and elsewhere too, increasingly erratic hydrological patterns mean the riverbeds will continue to change course and grow broader, forcing more farmers to deal with the effects of climate change. By utilizing an under-exploited resource and enhancing smallholders' productive skills on marginal soils, riverbed farming increases marginal farmers' options for sustainably coping with the effects of environmental shocks like floods. In sum, riverbed farming is an environmentally, economically, socially, and technologically sustainable that can contribute to creating rural employment opportunities and enhance marginal farmers' capacities to sustainably adapt to the effects of climate change.
- ↑ Gurung, G.B., Koirala, P., Pande, D.P., et al.2012. Promoting rural livelihoods through riverbed vegetable farming in the Tarai of Nepal. Journal of International Development and Cooperation 18(4): 113-121.
- ↑ In the Terai, this is usually the Village District Committee (VDC, the local Government authority). On occasion, it may be a private landowner or the local Community Forest User Group (CFUG).
- ↑ Chaudhary, P., Bawa. K.S. 2011. Local perceptions of climate change calidated by scientific evidence in the Himalayas. Biology Letters7:767–770.
- ↑ Dulal, H.B., Brodnig, G., Thakur, H.K. 2010. Do the poor have what they need to adapt to climate change? A case study of Nepal. Local Environment: The International Journal of Justice and Sustainability 15 (7): 621-635.
- ↑ Schiller, K., Kriesemer, SK., Gerster-Bentaya, M. 2013.Smallholders' adaptations to the effects of climate change: the sustainability of leasehold riverbed farming in the Terai. Paper presented at the International Conference on Tropical and Subtropical Agriculture and Natural Resource Management (Tropentag), University of Hohenheim.
- ↑ Dulal et al. 2010.
- ↑ Dulal et al. 2010.
- ↑ Privately funded or national extension services. Alternative ways of financing the LRPs are under discussion.
- ↑ In Nepal, this is usually the Village District Committee (VDC, the local Government authority). On occasion, it may be a private landowner or the local Community Forest User Group (CFUG).
- ↑ Schiller et al. 2013.
- ↑ International Fund for Agricultural Development (IFAD). 2013b. Smallholders, food security, and the environment. IFAD, Rome.
- ↑ Schiller et al. 2013.
- ↑ Schiller et al. 2013.
- ↑ Food and Agricultural Organization (FAO) Council. 1988. 94th Session.
- ↑ Schiller et al. 2013.
Helvetas Swiss Intercooperation Nepal. 2013. Natural resource management approaches and technologies in Nepal: technology riverbed farming. (9).pdf http://www.lib.icimod.org/record/28281/files/Technology
Riverbed, riverbank, and sandbar farming are seen across South Asia.
Helvetas Swiss Intercooperation Nepal's project description of riverbed farming: http://www.nepal.helvetas.org/en/our_projects/rbf.cfm
Riverbed Farming Alliance in Nepal: http://www.riverbedfarmingalliance.org.np
World Bank Development Marketplace, riverbed farming:http://wbi.worldbank.org/wbdm/stories/securing-livelihoods-through-riverbed-farming
Helvetas Swiss Intercooperation Nepal on riverbed farming: