TITLE:
From Farmyard to Field: Comparing Three Manure Blends and NPK Fertilizer for Garden Egg (Solanum melongena L.) Production under Ghanaian Conditions
AUTHORS:
Adjei Eric, Kwadwo Gyasi Santo, Adu Poku Isaac, Danson Anokye-Alexander, Kennedy Kontor, Grace Nartey, Ayensu Patrick, Sylvia Kyeremaah Hinneh
KEYWORDS:
Garden Egg, Solanum Melongena, Organic Manure, Integrated Nutrient Management, NPK Fertilizer, Smallholder Farmers, Ghana
JOURNAL NAME:
Agricultural Sciences,
Vol.17 No.9,
September
24,
2026
ABSTRACT: Continuous cultivation with limited organic inputs has accelerated soil fertility depletion across Ghana’s vegetable-producing regions, while increasing dependence on inorganic fertilizers has raised production costs and environmental concerns for smallholder farmers. Garden egg (Solanum melongena L.) is an economically and nutritionally important vegetable crop, yet the agronomic performance of locally available blended animal manures remains inadequately understood under Ghanaian conditions. Existing studies have primarily evaluated individual organic manure sources or compared organic and inorganic fertilizers, with limited attention to synergistic blends of poultry, cattle, and goat manures that differ in nutrient composition, nitrogen availability, and mineralization dynamics. This study compared three blended animal-manure combinations for garden egg production to determine which performed best and how its performance compared with conventional inorganic fertilization and no fertilization, over two consecutive cropping seasons in the humid semi-equatorial zone of Ghana. A field experiment was conducted during the 2019 minor and 2020 major cropping seasons using a randomized complete block design with five treatments replicated three times. Treatments comprised three organic combinations (1/2 chicken + 1/2 cattle manure, 1/2 chicken + 1/2 goat manure, 1/2 goat + 1/2 cattle manure) evaluated against NPK (15-15-15) as a positive control and an unfertilized treatment as a negative control. All organic treatments were applied at an equivalent nitrogen rate of 207 kg N ha−1. NPK consistently produced the highest fruit yield (0.789 and 1.103 t·ha−1 in 2019 and 2020, respectively). All three organic manure combinations significantly improved vegetative growth, biomass accumulation, and fruit yield relative to the unfertilized control, and were statistically comparable to one another in both seasons. In 2020, 1/2 goat + 1/2 cattle manure recorded the highest numerical fruit yield among the organic treatments (0.822 t·ha−1), but this difference was not statistically significant; no organic combination was consistently superior to the others across both seasons. These findings indicate that blended animal manures can meaningfully narrow, without closing, the productivity gap with inorganic fertilization, offering smallholder farmers a lower-cost nutrient management option whose relative performance depends on which manures are blended and on seasonal conditions.