Insect frass fertilizer as a regenerative input for improved biological nitrogen fixation and sustainable bush bean production

Agnes Chepkorir; Dennis Beesigamukama; Harun I Gitari; Shaphan Y Chia; Sevgan Subramanian; Sunday Ekesi; Birachi Eliud Abucheli; Jean Claude Rubyogo; Theodore Zahariadis; Gina Athanasiou; Aikaterini Zachariadi; Vasileios Zachariadis; Abdou Tenkouano; Chrysantus M Tanga

doi:10.3389/fpls.2024.1460599

Insect frass fertilizer as a regenerative input for improved biological nitrogen fixation and sustainable bush bean production

Front Plant Sci. 2024 Sep 5:15:1460599. doi: 10.3389/fpls.2024.1460599. eCollection 2024.

Authors

Agnes Chepkorir^{1

2}, Dennis Beesigamukama¹, Harun I Gitari², Shaphan Y Chia¹, Sevgan Subramanian¹, Sunday Ekesi^{1

3}, Birachi Eliud Abucheli⁴, Jean Claude Rubyogo⁵, Theodore Zahariadis^{6

7}, Gina Athanasiou⁶, Aikaterini Zachariadi⁶, Vasileios Zachariadis⁶, Abdou Tenkouano¹, Chrysantus M Tanga¹

Affiliations

¹ International Centre of Insect Physiology and Ecology, Nairobi, Kenya.
² Department of Agricultural Science and Technology, Kenyatta University, Nairobi, Kenya.
³ Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa.
⁴ International Centre for Tropical Agriculture, Kigali, Rwanda.
⁵ International Centre for Tropical Agriculture, Nairobi, Kenya.
⁶ Synelixis Solutions S.A., Chalkida, Greece.
⁷ Department of Agriculture Development, National and Kapodistrian University of Athens, Athens, Greece.

Abstract

Bush bean (Phaseolus vulgaris L.) production is undermined by soil degradation and low biological nitrogen fixation (BNF) capacity. This study evaluated the effect of black soldier fly frass fertilizer (BSFFF) on bush bean growth, yield, nutrient uptake, BNF, and profitability, in comparison with commercial organic fertilizer (Phymyx, Phytomedia International Ltd., Kiambu, Kenya), synthetic fertilizer (NPK), and rhizobia inoculant (Biofix, MEA Fertilizers, Nairobi, Kenya). The organic fertilizers were applied at rates of 0, 15, 30, and 45 kg N ha^-1 while the NPK was applied at 40 kg N ha^-1, 46 kg P ha^-1, and 60 kg K ha^-1. The fertilizers were applied singly and in combination with rhizobia inoculant to determine the interactive effects on bush bean production. Results showed that beans grown using BSFFF were the tallest, with the broadest leaves, and the highest chlorophyll content. Plots treated with 45 kg N ha^-1 BSFFF produced beans with more flowers (7 - 8%), pods (4 - 9%), and seeds (9 - 11%) compared to Phymyx and NPK treatments. The same treatment also produced beans with 6, 8, and 18% higher 100-seed weight, compared to NPK, Phymyx, and control treatments, respectively. Beans grown in soil amended with 30 kg N ha^-1 of BSFFF had 3-14-fold higher effective root nodules, fixed 48%, 31%, and 91% more N compared to Phymyx, NPK, and rhizobia, respectively, and boosted N uptake (19 - 39%) compared to Phymyx and NPK treatments. Application of 45 kg N ha^-1 of BSFFF increased bean seed yield by 43%, 72%, and 67% compared to the control, NPK and equivalent rate of Phymyx, respectively. The net income and gross margin achieved using BSFFF treatments were 73 - 239% and 118 - 184% higher than the values obtained under Phymyx treatments. Our findings demonstrate the high efficacy of BSFFF as a novel soil input and sustainable alternative for boosting BNF and improving bush bean productivity.

Keywords: BSF frass fertilizer; bush bean yield; circular economy; climate-smart fertilizer; soil health; symbiotic nitrogen fixation.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The authors gratefully acknowledge the financial support for this research by the following organizations and agencies: Australian Centre for International Agricultural Research (ACIAR) (ProteinAfrica –Grant No: LS/2020/154), Global Affairs Canada (BRAINS project: P011585), Novo Nordisk Foundation (RefIPro: NNF22SA0078466), the Rockefeller Foundation (WAVE-IN—Grant No: 2021 FOD 030); Bill and Melinda Gates Foundation (INV-032416); IKEA Foundation (G-2204-02144), European Commission (HORIZON 101060762 NESTLER and HORIZON 101136739 INNOECOFOOD), the Curt Bergfors Foundation Food Planet Prize Award; Norwegian Agency for Development Cooperation, the Section for Research, Innovation, and Higher Education grant number RAF–3058 KEN–18/0005 (CAP–Africa); the Swedish International Development Cooperation Agency (Sida); the Swiss Agency for Development and Cooperation (SDC); the Australian Centre for International Agricultural Research (ACIAR); the Norwegian Agency for Development Cooperation (Norad); the German Federal Ministry for Economic Cooperation and Development (BMZ); the Federal Democratic Republic of Ethiopia; and the Government of the Republic of Kenya. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The views expressed herein do not necessarily reflect the official opinion of the donors.