Agronomic assessment of the yield variability and yield gap of maize in Bhutan

Abstract

Maize is the staple food crop in Bhutan, which has not achieved national food self-sufficiency. On-farm assessment of yield variability would provide insights into the priorities for Bhutan's maize development program. Here, we conducted three studies in Bhutan: a household survey, on-station experiment, and on-farm monitoring. First, we interviewed 100 households and collected information on maize crop management options and farming characteristics. Second, we evaluated maize growth at two research stations in different elevation zones (640 and 1,700 m a.s.l.). Third, we harvested maize from 25 farm fields at low and high elevations. The gaps between potential yield (with the best management practices at the research stations) and average farm yield and between the best and average farm yields were 53% and 23%, respectively, at the low elevation, and 23% and 20%, respectively, at the high elevation. The classification and regression tree (CART) model showed that field location (distance from the farmer's home), seed source (certified vs. self-produced), and the number of household members involved in farming were the key farming characteristics that affected yield variability, and the manure application regime, urea application, sowing method, and weeding frequency were key management practices. Our results suggest that future research should clarify the most suitable sowing methods and nutrient and weed management regimes, and identify optimal cultivars for each elevation zone, with the goal of developing crop management guidelines for smallholder farmers in Bhutan.

Keywords

Bhutan / Classification and regression tree model / Maize / Management practice / Yield gap / Yield variability

Abbreviations

Not applicable.

Availability of data and materials

Data will be shared upon request by the readers.

Authors' contributions

W.P.: investigation, formal analysis, and writing original draft; K.T.: writing, review, and editing; T.N.: writing, review, and editing; and Y.K.: conceptualization, supervision, funding acquisition, writing, review, and editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Author Yoichiro Kato (Editorial Board member) was not involved in the journal's review nor decisions related to this manuscript.

Acknowledgements

We are grateful for support from the Agriculture Research and Development Centre of Bhutan in carrying out this study. We thank Ms. Kinley Wangmo, Tashi Dema, and Tshering Choden for their technical assistance. This study was financially supported in part by the Project for Human Resource Development Scholarship by Japanese Grant Aid (JDS, to P.W.) and the Japan Society for the Promotion of Science (JSPS, no. 18KK0169, to Y.K.).

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.crope.2023.11.003.

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