Abstract

Cassava is the most widely cultivated root crops among traditional farmers in the Midwestern Nigeria. Majority of the traditional farmers employ the zero tillage system. It is unclear if zero tillage is the best practice for optimizing yield? This study investigates the impact of tillage types on soil microclimatic condition, growth and yield of cassava in Midwestern Nigeria. An experimental area that measured 17 by 47 m was established in Agbor, Delta State, Nigeria for two planting seasons 1997/1998 and 1998/1999. The microclimatic parameters monitored include air and soil temperatures and relative humidity while the physiological parameters measured were emergence, growth rate, leaf area accumulation and yield. Time series, multiple correlation, chi-square., ANOVA and stepwise regression analyses were the statistical tools employed in analysing the data. The results showed that soil moisture at 0 - 15 cm depth was significantly higher in zero tillage, followed by ridge and mound. The reverse is true with soil temperature. Ridge tillage (9.6 t ha^-1) significantly produced more cassava tubers, followed by mound tillage (7.5 t ha^-1) and zero tillage (5.2 t ha^-1). The conventional ridge tillage method is recommended because it yielded more than the local practice of the zero tillage by 46%.

Key words: Nigeria, tillage types, microclimate, hydrothermal, ethnoscience, cassava yield.