The underutilized terrace wall can be intensified to improve farmer livelihoods

Millions of vulnerable smallholder farmers around the world cultivate crops on narrow hillside terraces and suffer from inadequate flat growing areas to support their families. A significant amount of surface area on terraces is actually vertical—specifically the underutilized terrace walls (risers). Some indigenous farmers in Nepal have been observed to cultivate wall-climbing and wall-descending crops, sown at the base or top edge of the walls, respectively, but these have not been evaluated for their economic benefits and adoption potential. Participatory on-farm trials were conducted on 280 terrace farms in two districts of Nepal (Kaski, Dhading) for two cropping seasons (2015–2016). Three wall-climbing crops (yam in sacks, chayote squash, pumpkin) and four wall-descending crops (ricebean, cowpea, horsegram, blackgram) were each grown by 20 farmers per crop per site and evaluated for potential net economic returns and perceptions of all 280 participating women farmers based on five adoption criteria. Here, we show, for the first time to the best of our knowledge, that terrace walls or risers can be intensified with suitable wall-climbing and wall-descending crops. All three wall-climbing crops were productive, with potential net economic returns ranging from US $27 per plant for chayote squash, $10/plant for pumpkin, and $2/plant for yam. Similarly, all four wall-descending crops were productive, with potential net economic returns ranging from US $9–$15 per 100 m of wall edge. All the wall crops received good-to-excellent ratings (typically > 8/10) by women farmers for simplicity, compatibility, affordability, potential economic returns, and willingness to continue. In terms of long-term adoption, yam, pumpkin, ricebean, and cowpea were ranked the highest, with > 90% farmers willing to continue each practice. We discuss the potential and constraints of transferring these terrace-intensifying strategies globally.