Economic Analysis of Soilless Media and Deficit Fertigation Strategies in Greenhouse Tomato Production in Wet and Dry Seasons

Abstract

Greenhouse tomato production in Ghana is expanding, yet high input costs, particularly imported soilless substrates and irrigation, limit profitability. This study evaluated the economic viability of locally formulated soilless media under different deficit fertigation regimes for greenhouse tomato production across wet and dry seasons from May to October 2023 and October 2023 to March 2024, respectively. The experiment utilized a split-plot design with three deficit fertigation (DF) (40%, 20%, and 0% DF) as the main plot and four soilless media: 100% Cocopeat (CP₁₀₀), 60% Cocopeat + 40% Rice husk biochar (CP₆₀ + RHB₄₀), 40% Cocopeat + 40% Sawdust + 20% Sorghum haulm biochar (CP₆₀ + SD₄₀ + 20% SHB₂₀), and 60% Cocopeat + 40% Rice husk (CP₆₀ + 40% RH₄₀) as the sub-plot treatments utilizing four replications. Profitability was assessed using the Benefit-Cost Ratio (BCR) and Marginal Rate of Return (MRR). The results showed that yield and financial returns were significantly influenced by the media type and deficit fertigation. Tomato yield increased with decreasing deficit fertigation in both seasons. Wet-season yields ranged from 32.7 to 72.0 kg m⁻², while dry-season yields declined to 20.7-71.8 kg m⁻². Across all fertigation regimes, the CP₆₀ + RHB₄₀ consistently produced the highest yields and revenues. At 0% deficit fertigation, CP₆₀ + RHB₄₀ recorded the highest BCR in both the wet (1.93) and dry (2.20) seasons, outperforming 100% Cocopeat (1.47 and 1.78, respectively). Partial budget analysis showed that replacing 40% of cocopeat with rice husk biochar under 40% DF reduced substrate costs by approximately 20-30% and generated exceptionally high marginal returns, with a 17501% marginal rate of return in the wet season and 461.5% under 0% DF in the dry season. Media containing raw rice husk consistently recorded the lowest economic returns. The results demonstrate that locally available rice husk biochar can partially replace imported cocopeat while enhancing profitability. Adoption of CP₆₀ + RHB₄₀ with 40% to 20% DF offers a cost-effective strategy for farmers and supports sustainable greenhouse intensification aligned with SDGs 2, 6, and 12.