Beyond nutrients: Frass fertilizer legacy effects for sustainable nematode management in potato–African nightshade rotation systems

Publication Type

Journal Article

Journal Name

Farming System

Name of Author

• Emmanuel O. Anedo, International Centre of Insect Physiology and Ecology Nairobi
• Dennis Beesigamukama, International Centre of Insect Physiology and Ecology Nairobi
• Benson Mochoge, Kenyatta University
• Nicholas K. Korir, Kenyatta University
• Solveig Haukeland, International Centre of Insect Physiology and Ecology Nairobi
• Xavier Cheseto, International Centre of Insect Physiology and Ecology Nairobi
• Moses Nyongesa, Kenya Agricultural & Livestock Research Organization
• Patrick PwaiPwai, Kenya Agricultural & Livestock Research Organization
• Sevgan Subramanian, International Centre of Insect Physiology and Ecology Nairobi
• Abdou Tenkouano, International Centre of Insect Physiology and Ecology Nairobi
• Chrysantus M. Tanga, International Centre of Insect Physiology and Ecology Nairobi

Publication Date

10-1-2026

Abstract

The utilization of insect frass fertilizer in crop production systems has recently gained significant global interest, but there has been limited evidence of its residual benefits in rotational cropping systems. The legacy effects of black soldier frass fertilizers (BSFFF), conventional organic fertilizer (SAFI), inorganic fertilizer (NPK), synthetic nematicide, and their combinations on potato cyst nematode (PCN) management under potato-African nightshade rotational farming systems were investigated. Eight treatments were evaluated: BSFFF, SAFI, chitin-fortified BSFFF (BSFFF+5chitin), NPK + nematicide, combination of BSFFF and NPK so that each supplies 50% of the nitrogen required by potato (50BSFFF+50NPK), combination of SAFI and NPK so that each supplies 50% of the nitrogen required (50SAFI+50NPK), chitin-fortified BSFFF and NPK so that each applies 50% of the nitrogen required (50BSFFF+5chitin+50NPK), and unfertilized soil (control). The amendments were applied for four consecutive seasons, and the residual benefits were assessed. The yield and crude protein of nightshade produced were 10 – 153% and 21–31% higher, respectively, compared to the control. Moreover, BSFFF treatments enhanced nightshade yield and crude protein content by 15–61% and 27–33%, respectively, relative to the other amendments. Plots amended with BSFFF+ 5chitin produced African nightshade with 47–71% and 23–87% more leaf numbers and branches than the other amendments. The fertilizer amendments significantly reduced the cyst density by 56 – 71%, and cyst eggs and second stage Juveniles (J2) per g of soil by 87 – 94% compared to the control. The BSFFF+5chitin was superior in reducing PCN population (87 – 94%) compared to other amendments. The BSFFF-based fertilizers significantly improved key soil chemical properties (pH, electrical conductivity, mineral nitrogen, and available phosphorus). These findings provide evidence on the residual effects of BSFFF on soil fertility, crop productivity, and PCN management, and act as a benchmark for guiding regenerative strategies for enhancing productivity and sustainability of smallholder potato-nightshade rotation systems.

Keywords

Agricultural productivity, Circular economy, Crop rotation, Nematode management, Regenerative agriculture, Residual benefits

Recommended Citation

Anedo, E., Beesigamukama, D., Mochoge, B., Korir, N., Haukeland, S., Cheseto, X., Nyongesa, M., PwaiPwai, P., Subramanian, S., Tenkouano, A., & Tanga, C. (2026). Beyond nutrients: Frass fertilizer legacy effects for sustainable nematode management in potato–African nightshade rotation systems. Farming System, 4 (4) https://doi.org/10.1016/j.farsys.2026.100239