Evaluating the Effectiveness of Rhizobium Inoculants and Micronutrients as Technologies for Nepalese Common Bean Smallholder Farmers in the Real-World Context of Highly Variable Hillside Environments

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February 2019



Abstract: Studies have shown the potential of rhizobia and associated micronutrients to enhance symbiotic nitrogen fixation in legumes. Tens of millions of smallholder farmers, however, farm on mountain hillsides in highly variable soil and microenvironments, with different crop rotations,\r\ninputs and cultural practices. Here, on the terraces of the Nepalese Himalayas, we evaluated rhizobium inoculants (local, exotic), micronutrients (molybdenum, boron) and their combinations as technologies for smallholder farmers under highly variable microenvironments and traditional\r\npractices. The study was conducted as a series of participatory on-farm trials with 39 terrace farmers in two mid-hill districts of Nepal (Dhading, Kaski) from 2015 to 2017. Plots were measured for relevant agronomic traits. As expected, when comparing treatment plots with adjacent control plots\r\nwithin each farm, the results demonstrated tremendous farm-to-farm variability for nodulation, vegetative biomass, shoot nitrogen content, grain yield, and grain N content. Despite the variation observed, the data showed that the number of farms that showed yield increases from the rhizobium\r\ninterventions, compared to those that suffered yield losses, was generally 2:1. We discuss potential experimental and socio-agronomic reasons for the variable results, including rainfall, which appeared critical. The results demonstrate the promise of rhizobium interventions for hillside smallholder\r\nfarmers, even in a highly variable context.
\r\nKeywords: common bean; legume; nodule; nitrogen fixation; terrace farmer; micronutrients"}” data-sheets-userformat=”{"2":829,"3":{"1":0},"5":{"1":[{"1":2,"2":0,"5":{"1":2,"2":0}},{"1":0,"2":0,"3":3},{"1":1,"2":0,"4":1}]},"6":{"1":[{"1":2,"2":0,"5":{"1":2,"2":0}},{"1":0,"2":0,"3":3},{"1":1,"2":0,"4":1}]},"7":{"1":[{"1":2,"2":0,"5":{"1":2,"2":0}},{"1":0,"2":0,"3":3},{"1":1,"2":0,"4":1}]},"8":{"1":[{"1":2,"2":0,"5":{"1":2,"2":0}},{"1":0,"2":0,"3":3},{"1":1,"2":0,"4":1}]},"11":4,"12":0}”>
Keywords: common bean; legume; nodule; nitrogen fixation; terrace farmer; micronutrients