Demand-Driven Technologies for Sustainable Maize ... - IITA

126Figure 1: Rainfall pattern in Samaru from 1998 to 2000.the plots were prepared manually to maintain plot properties. Plot sizewas 4 m x 6 m, representing an area of 24 m 2 . An extra-early maturingopen-pollinated maize variety, 95 TZEE-W was the test crop.The soil characteristics of the site at the initiation of the study weredetermined from composite samples of surface soils. Particle sizedistribution was carried out by the hydrometer method (Bouyoucos1951), while the Micro-kjeldhal wet digestion method was used todetermine total N (Bremner 1965).Walkley and Black method was used to determine organic carbon(Page et al. 1982). Soil pH was determined in water and in 0.01M CaCl 2at a soil:solution ratio of 1:2.5 (weight:volume) with a glass electrode.Exchangeable bases were displaced with 1N NH 4OAc buffered at pH7.0. Potassium and sodium in the extract were determined with thefl ame photometer; calcium and magnesium were determined with theatomic absorption spectrophotometer. Available P was determined bythe Bray I method (Bray and Kurtz 1945). The ECEC was determinedby summing the values of exchangeable bases and exchangeableacidity, which was determined by 1N KCl extraction.