Climbing Legumes: An Underutilized Resource With Significant Potential to Intensify 3 Farming on Terrace Walls (FTW) for Smallholder Farmers

44 45 Millions of subsistence farmers cultivate crops on terraces. These farmers face unique challenges 46 including severe shortages of arable land and remoteness leading to poor access to inputs 47 including nitrogen fertilizer. These challenges contribute to human and livestock malnutrition. 48 Terrace walls (risers) as a vertical surface to grow climbing or trailing legumes represents an 49 opportunity to help overcome these challenges. These crops are rich in minerals and protein, and 50 their associated microbes produce nitrogen fertilizer. Rice bean is already grown on terrace risers 51 in South Asia. This paper reviews the literature concerning crops that are currently farmed on 52 terrace walls (FTW), then surveys climbing legume species that have potential for FTW, 53 focusing on crops that are nutritious and tolerate shade (caused by the terrace wall) and resist 54 drought (many terrace farms experience an extended dry season). A total of 29 legume species 55 are discussed including climbing varieties of jack bean, common bean, cowpea, winged bean, 56 horse gram and velvet bean. The review concludes by discussing the practical challenges of 57 farmer adoption of FTW and makes concrete recommendations. Terrace wall cultivation of 58 legumes represents an opportunity to intensify agriculture and increase resiliency in remote 59 mountainous areas. 60 61 peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission. The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/184952 doi: bioRxiv preprint first posted online Sep. 5, 2017;