Assessing the impact of deficit irrigation and effective microorganisms (EM) for optimizing water productivity on bell pepper production in arid climatic area of northern Ghana.

Abstract

Deficit irrigation strategy that are combined with other organic fertilizer amendments like effective microorganisms (EM) play a major role in vegetable production, specifically in the water scarcity area of Northern Ghana, where long-term erratic and uneven distribution of rainfall is observed annually. In recent years, few studies have been conducted on assessing the impact of deficit irrigation and effective microorganisms (EM) to maintain high vegetable yields while at the same time increasing water productivity. In this context, an experiment was designed during the two cropping seasons (May 2023 to February 2024) at the WACWISA field plot in a Randomized Complete Block Design (RCBD) with three replicates whereby 90% ETc, 75%ETc, 50%ETc and 35%ETc of crop evapotranspiration were applied. Four EM treatments, T1 (0.8L/m²/d), T2 (0.60L/m²/d), T3 (0.4L/m²/d) and T4 (0L/m²/d) (Control) were applied to the crop at the initial, development, middle, and late stages of the crop growing seasons.

CROPWAT 8.0 Software was used to estimate crop water requirements during the entire crop season. Meteorological data for 20 years (2004–2024) was obtained from the Savannah Agricultural Research Institute (SARI) in Ghana, Northern Region. Climatic, soil, and crop parameter data were used to calculate the crop water requirement, irrigation amount needed during each growth stage, and finally the irrigation scheduling of bell peppers using the Penman-Monteith method as described by FAO Paper 56.

In this study, the results revealed that bell pepper yields due to the application of effective microorganisms (EM) and deficit irrigation were higher and consistent in both cropping seasons, even though there were significant differences between deficit irrigation regimes of 50% ETc and 35% ETc. The study revealed that by utilizing T1 (0.80L/m²/d) and T2 (0.60L/m²/d) EM treatments, high pepper market yields were observed at 16.6 tons/ha and 15.3 tons/ha, respectively, with reasonable increased water productivity of 28% and 15%, respectively. To put into conclusion, deficit irrigation regimes of 90% ETc and 75% ETc were comparatively recommended for increasing pepper yield production and maximizing water productivity scenarios under the arid climatic conditions of northern Ghana.

Keywords: deficit irrigation, effective microorganisms (EM), CROPWAT 8.0 software, water productivity and Bell pepper

DOI: 10.7176/JBAH/16-1-01

Publication date: May 31^st 2026