Rice Cultivation and Weed Control in Ghana’s Guinea Savannah Zone

Rice production in the Guinea Savanna agroecological zone of Ghana faces persistent challenges from weed infestation, soil moisture losses, and high production costs associated with conventional land preparation practices. Conservation-oriented management strategies that integrate reduced tillage and efficient weed control are increasingly recognised as pathways to sustainable intensification of rice-based systems. This chapter evaluates the interactive effects of tillage practices and herbicide-based weed management on weed control efficiency, soil moisture conservation, crop growth, grain yield, and economic performance of rice (Oryza sativa L.). Field experiments were conducted in 2022 at the Nyankpala experimental field of the Savannah Agricultural Research Institute (SARI) using a factorial combination of tillage systems (conventional, minimum, and no tillage) and herbicide regimes: Pendimethalin (400 g a. i. ha⁻¹) applied as pre-emergence, Bispyribac sodium (25 g a. i. ha⁻¹) applied as post-emergence, and a combined pre- and post-emergence application. Agronomic data on weed density, weed biomass, crop vigour, phenological development, and grain yield were collected. Weed control efficiency was quantified, and enterprise budgeting was complemented with sensitivity and risk analyses to assess economic robustness under variable cost and price scenarios. The results showed that minimum tillage combined with pre- and post-emergence herbicide application significantly reduced weed density and biomass, improved soil moisture retention, enhanced crop vigour, accelerated flowering, and increased grain yield compared with conventional tillage systems. Economic analysis indicated that the integrated minimum tillage-herbicide system generated higher net returns and remained economically resilient under simulated input cost increases and output price reductions. This chapter demonstrates that integrated tillage-herbicide management enhances productivity, profitability, and environmental sustainability of rice-based systems in the Guinea Savanna, providing practical evidence to support the wider adoption of conservation agriculture in sub-Saharan Africa.