Chapter 3.2a
3.2a - Climbing beans on terrace walls
Noah Dion, University of Guelph, Canada
Suggested citation for this chapter.
Dion,N(2022) Climbing beans on terrace walls. In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org
Introduction to the Farming Practice
Terrace farming is a practice that has been exercised over the past 5000-6000 years, primarily in hilly, rural regions where there is not an abundance of flat farmland to be cultivated. These terraces are utilized mostly by farmers in South Asia (e.g. China, India, Nepal, etc.), East Africa (e.g. Ethiopia, Tanzania, etc.) and South American regions (Chapagain et al., 2019). The terrace wall gives the farmer the ability to use poor farmland in mountainous regions by building risers up the hilly parts of the land, like a staircase. The terrace is made up of three main components: the flat land in between each riser (step-up) that is cultivated mainly with field crops, the slim narrow path on the edge allowing farmers to navigate their way through the land and tend to the crops, and the riser which is usually a bare wall either constructed with a sturdy material or dug out and man-made. In Nepal, for example, a terrace wall's dimensions are: 4-5 m in height and 50-100 m in length, with the flat land in between each step being roughly 3-4 m in width (Chapagain et al., 2019). This means that more than half the potential surface area is unused – in particular, the vertical surface. Growing crops, in particular climbing beans, at the base of the terrace wall offers an opportunity to improve local nutrition, the environment and alleviate poverty.
Climbing Bean Candidates for Cultivation on Terrace Walls
The legume family is the 3rd largest family out of all flowering plants, hosting approximately 20,000 different species (Doyle, 1994). Some examples of these legumes (more specifically climbing beans) are the cowpea, common bean, winged bean, etc. There are many different types of climbing beans that are candidates for successful growth on terrace walls. These could be planted at the base of the walls. The jack bean (also known as Canavalia ensiformis) is a great example of a legume that would thrive in this environment. Native to the West Indies and Central America, these beans hold potential to grow on the terrace walls because they are tolerant to waterlogging as well as drought tolerant (Haq, 2011). They can survive on as little as 650 mm of rainfall per year (Clark and Raizada, 2017). The winged bean (also known as Psophocarpus) is another potential candidate for climbing the terrace walls. This crop shows potential based on its agronomic and nutritional traits and is usually grown by subsistence farmers. Their seeds contain a significant amount of protein (37.3%) (Cerny et al., 1971). Unfortunately this bean is very underutilized and lacks adequate research.
Benefits of Growing Climbing Beans on Terrace Walls
Implementing climbing beans into terrace farming will increase overall legume yields which can lower poverty and malnutrition rates in the hilly regions. Beans add nitrogen to the soil to assist other crops, as well as protein to food and fodder for human and livestock diets, respectively (Rondon et al., 2007). There are many benefits that make farming on terrace walls appealing. Terrace risers are designed to prevent erosion from rainwater. They do this through their ability to slow the amount and velocity of the rainwater by collecting rainfall accumulating on the slope of the risers, which in turn slows the erosion process (Wheaton and Monke, n.d.). In addition, more efficient farming can be practiced through the wall's ability to collect and hold more water. In Nepal, the agricultural land holding on average is about 0.68-0.77 ha for hilly/mountainous regions (Clark and Raizada, 2017) so incorporating terrace walls into crop production will benefit the subsistence farmers in these regions greatly.
Potential Hardships
There are many challenges to consider when implementing this method of farming as it can be a very tedious and laborious (Clark and Raizada, 2017). The height and trajectory of the cultivated land on the terrace walls can make farming the climbing beans very physically challenging, especially for smallholder women farmers that are unfortunately not always as physically capable as a stronger male farmer in certain circumstances. The direction the wall is facing is very important when relating to overall sun exposure. Climbing crops may shade the crops that are growing on the horizontal land in between the terrace risers which would tamper with the growing process. Also, when the sun is no longer shedding light on the face of the wall, the climbing legumes will have a lack of sunlight. Climbing beans may not be compatible with other terrace crops or crop production methods (e.g. flooded rice paddies) (Clark and Raizada, 2017).
Socio-Economic Challenges
There are also socio-economic hardships to consider since the hilly regions that the terrace farmers populate are typically suffering from poverty. In these regions, there can be a lack of human capital since many men migrate to the city or other countries for employment (Chapagain and Raizada, 2017). In Nepal, over 30% of the population live on $14 USD per month, where 75% of the population in the hilly regions live below the poverty line (Chapagain and Raizada, 2017). Therefore, constructing and maintaining terrace farms is not a very feasible option for the economically struggling countries in these mountainous regions, and hence this practice would be limited to farmers that already have terraces.
Picture Based Lesson to Train Farmers
Practical Links to Get Started
https://www.youtube.com/watch?v=cFPbuinYXA0 Video on the construction and irrigation of terraced farmland
https://www.biorxiv.org/content/10.1101/184952v1.full Article listing many different examples of climbing legumes
https://www.youtube.com/watch?v=LpaPU-STAsY Video discussing soil conservation
References
1. Pratap, A. and Kumar, J. (2011). Underutilized Food Legumes: Potential for Multipurpose Uses. In A. Pratap and J. Kumar (Eds.), Biology and Breeding of Food Legumes. Cambridge: CAB International. https://www.biorxiv.org/content/10.1101/184952v1.full
2. Cerny, K., Maud, K., Pospisil, F., Svabensky, O., and Zajic, B. (1971) Nutritive value of the winged bean (Psophocarpus palustris Desv.). British Journal of Nutrition. 26, 293–299. https://www.biorxiv.org/content/10.1101/184952v1.full
3. Chapagain, T., Ghimire, B., Pudasaini, R., Gurung, K., Choi, K., Rai, L., Magar, S., Bishnu, B. K., & Raizada, M. N. (2019). The underutilized terrace wall can be intensified to improve farmer livelihoods - agronomy for sustainable development. Agronomy for Sustainable Development 39, 29. https://link.springer.com/article/10.1007/s13593-019-0574-2
4. Chapagain, T., & Raizada, M. N. (2017). Agronomic challenges and opportunities for Smallholder Terrace Agriculture in developing countries. Frontiers in Plant Science 8, 331. https://www.frontiersin.org/articles/10.3389/fpls.2017.00331/full
5. Clark, J. C., & Raizada, M. N. (2017). Climbing legumes: an underutilized resource with significant potential to intensify farming on terrace walls (FTW) for smallholder farmers. bioRxiv. https://www.biorxiv.org/content/10.1101/184952v1.full
6. Doyle, J. J. (1994). Phylogeny of the legume family: approach to understanding the origins of nodulation. nnnual review of ecology and systematics, Annual Review of Ecology and Systematics 25, 325–349. http://www.jstor.org/stable/2097315
7. Rondon, M.A., Lehmann, J., Ramírez, J. et al. (2007). Biological nitrogen fixation by common beans (Phaseolus vulgaris L.) increases with bio-char additions. Biol Fertil Soils 43, 699–708. (https://doi.org/10.1007/s00374-006-0152-z
8. Wheaton , R. Z., & Monke, E. J. (n.d.). Terracing as a `best management practice' for controlling erosion and protecting water quality. Purdue University, Cooperative Extension Service. https://www.extension.purdue.edu/extmedia/ae/ae-114.html#:~:text=The%20major%20benefit%2C%20of%20course,than%20would%20otherwise%20be%20possible.