Relationship Between Measured and Calculated Yield of Cassava and Yam Under Peasant Farm Management System in Soils of Ibadan, Nigeria

Abstract

The relationship between measured and calculated yield of yam and cassava under peasant farm management in the soils of Ibadan area was investigated. Precambrian basement complex rocks underlie the area. A site heavily cultivated by peasant farmers and sufficiently represents the geology, soils, vegetation and land use pattern of Ibadan was selected for the study. Forty-five plots under cassava and yam cultivation were selected to cover the twelve series in the area. The soils have texture ranging from loamy sand t sandy clay with weak crumb and granular structure in the surface layer. The highly concretionary and gravelly surface layers of Gambari and low soil series constitute a problem for the tillage implements. The soils classified as Alfisols, Entisols and Inceptisols have high fertility indices 42.84 to 81.99 and very low to high productivity indices 3.77 to 60.91. Soil productivity was limited mainly by soil depth, drainage and surface stoniness. Crop yields were predicted from the relationship between the yield to productivity index using the measure yield value of one of the soils. Measured cassava yield fro 6.3 to 11.5t/ha. While calculated yield range from 2.69 to 11.5t/ha. Measured yam yield range from 1.2 to 5.Ot/ha while calculated yield range from 2.85 to 6.4 t/ha. Peasant farmers have been able to cultivate these soils by tilling with hoes machetes and making heaps for yams and cassava. Results indicate positive correlation between measured and cultivated yield r =0.81 for yam and 0.77 for cassava with good predictive values of Y =2.51 + 0.71X and Y = 1.36 + 0.74X for yam and cassava respectively. Chi-squared analysis showed the independence between measured and calculated yield.



[Niger Agric. J. 33 (2002): 109-118]