Effects of farm-made biofertilizers on stem borer prevalence, natural enemy dynamics, grain yield and nutritional status of sorghum.
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Date
2026
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Busitema University
Abstract
Stem borer (Busseola fusca) infestation and declining soil fertility are major constraints to sorghum (Sorghum bicolor L. Moench) production among smallholder farmers in eastern Uganda. This study evaluated the agroecological effects of farm-made biofertilizers prepared from cow dung and forest organic matter on stem borer suppression, natural enemy dynamics, grain yield, and grain nutritional quality of sorghum under field conditions in eastern Uganda. A 2 × 4 x 8 split plot experiment arranged in a Randomized Complete Block Design (RCBD) with four replications was used across the four sorghum-growing districts, Soroti, Amuria, Katakwi, and Pallisa, where the experiments were hosted. Two sorghum varieties (NAROSORG 2 and Edeidei) were evaluated under eight treatment combinations including solid formulation, liquid soil drench, combined formulations, an untreated control, and a mineral fertilizer (DAP) positive control (CD-S, FO-SC, CD-S-L, FO-S-L, CD-L, FO-L, CON, DAP). Data were analysed using Three-way ANOVA in R, with Tukey's HSD test for mean separation at P ≤ 0.05. The combined cow-dung seed coating plus liquid drench treatment (CD-S-L) consistently outperformed other bio-fertilizer treatments. It recorded the lowest stem tunnel length (32.9 cm) and lowest dead-heart incidence (1.86 ± 0.10 dead hearts per plot), representing approximately 20% and 46% reductions relative to the untreated control, respectively. CD-S-L also significantly enhanced natural enemy diversity (Shannon H' = 1.03 ± 0.04), increasing abundance of spiders, ladybird beetles, and tachinid flies. Location significantly influenced sorghum productivity (P < 0.05). Pallisa recorded the highest grain yield (1,891.30 kg ha⁻¹), dry root weight (8.90 g), dry shoot weight (124.02 g), and total dry matter (132.92 g), while Katakwi produced the highest average panicle weight (301.97 g) and 1000-seed weight (18.34 g). Soroti recorded the lowest grain yield (1,630.28 kg ha⁻¹), whereas Amuria had the lowest dry root weight (4.50 g), dry shoot weight (59.25 g), and total dry matter (63.74 g). Grain yield under CD-S-L (2,118.7 kg ha⁻¹) was 64% higher than the untreated control (1,288.9 kg ha⁻¹), and the treatment recorded the highest grain nitrogen (3.3%) and iron (0.031%) concentrations among biofertilizer treatments. These findings demonstrate that farm-made biofertilizers, particularly combined formulations, can simultaneously improve stem borer suppression, natural enemy activity, grain yield, and nutritional quality. Nonetheless, the study spanned one season restricting what can be concluded on long term microbial persistence alongside soil health results. Nonetheless, the combined cow-dung biofertilizer formulation results present a low cost, viable and agroecologically sustainable option for small holder farmers in Uganda to adopt in and replace synthetic inputs to enhance sorghum production.
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Undergraduate research report
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Citation
Sembera, Y. J. (2026). Effects of farm-made biofertilizers on stem borer prevalence, natural enemy dynamics, grain yield and nutritional status of sorghum. [Unpublished undergraduate research report]. Busitema University.