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Journal of Applied Sciences

Year: 2017 | Volume: 17 | Issue: 1 | Page No.: 12-21
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Authors

Boasiako Ohene Antwi

Stephen K. Asante

Joseph Yeboah

Keywords

Research Article

Drought Assessment for Reduced Climate Impact on Cassava Production

Boasiako Ohene Antwi, Stephen K. Asante and Joseph Yeboah
Background: Cassava has been identified for food security and poverty alleviation in Northern Ghana. Unfortunately, understanding climate change and the stress on cassava establishment and production are the major problems currently addressed by IFAD-Ghana project (ProVACCA). Objective: The main objective of this study was to use simple tools for drought assessment, onset and cessation of rainy season and implement improved soil tillage system for cassava establishment. Materials and Methods: Standardized Precipitation Index (SPI) was used to assess drought severity at three-month time steps. Hydrological climate and precipitation accumulation models were used to determine onset and cessation of rainy season. Cone penetration tests were used to determine soil compaction on ridges across slope and mounds. Stat-Plus professional 5.8 was used for statistical analysis. The ability of cassava crop to withstand drought was assessed by yield of crop biomass, roots and harvest index. Results: Daytime temperatures and wind speed showed 73 and 71% correlation with evapotranspiration, respectively. The SPI accounted for 50-70% of drought severity. Models for onset and cessation of rainy season showed June-November to be the most reliable period to establish cassava. The highest cone penetration tests were 40 kPa. It occurred at 220 mm for ridges, 300 mm for mounds and 20 mm in furrows. Mulched ridges conserved more soil moisture within the rooting zone compared to planting on un-mulched ridges. The difference in mean yield of cassava biomass on ridges (22.92 t ha–1) and those on mounds (15.8 t ha–1) was insignificant at p≤0.05. However, there was significant difference between the harvest indices of cassava planted on ridges (58.77%) and those on mounds (51.02%) at p≤0.05. Conclusion: Planting within defined onset and cessation of rainy season using soil-water-conserving tillage practices reduced climate stress on cassava. Separating normal drought assessment criterion into positive and negative components removed the limitations of Standardized Precipitation Index for drought assessment in dry areas of Ghana.
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