Tuber Production of Cassava at Different Plant Spacing and Subsequent Effect on Soil Physical and Chemical Properties

The study aimed at identifying the influence of different plant population (plant spacing) on cassava tuber yield and the cumulative residual effect on soil physical and chemical properties were carried out in two cropping seasons (2008/2009 and 2009/2010) at Orin Ekiti research station of the Institute of Agricultural Research and Training (IAR&T), Moor Plantation Ibadan. The highest percentage change (50.58%) for soil bulk density was recorded for cassava population at 17,689 plants per hectare (75 x 75 cm spacing) while the least value (13.95%) was recorded for cassava population at 10,000 per hectare (100 x 100 cm spacing). The highest percentage change (23.38%) of soil pH was recorded for cassava plant population at 17,689 plants per hectare while the lowest percentage change (0.77%) of soil pH was recorded for cassava plant population at 10,000 plants per hectare. There was reduction in organic C (- 24.37%) at cassava plant population of 10,000 plants per hectare and -52.69% at plant population of 17,689 plants per hectare. Total soil N reduces from initial content before planting by -21.87% at plant population of 10,000 plants per hectare to -56.25% at plant population of 17,689 plants per hectare. Available P was generally increased with the corresponding increased in cassava plant population. The lowest percentage change (8.17%) was recorded for cassava population of 10,000 plants per hectare while the highest value (53.91%) was recorded for plant population at 17,689 plants per hectare. Exchangeable K was generally reduced after two years of putting the soil into cassava production at different plant population. The percentage changes of -31.59, - 42.11, -57.89, -73.95, and -89.47% were recorded for 10,000, 12,321, 13,333, 14,763 and 17,689 plants per hectare respectively. There were no significant (P < 0.05) differences among the various cassava plant population for average number of tuber per plant, average tuber diameter, and average tuber weight in 2008 and 2009. In both years of experimentation, there were significant (P < 0.05) differences in fresh cassava tuber yield. The significantly highest fresh cassava tuber yields 32.4 and 27.3 t-1 for 2008 and 2009 respectively were obtained given by plant population at 17, 689 plants per hectare.