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

158Table 1. Monthly distribution and total amount of rainfall at theexperimental site, 2001 and 2002.Month Amount of rainfall (mm)2001 2002JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember0.00.00.083.9160.3177.7388.4330.7256.30.00.00.00.00.019.960.910.6133.1229.0201.4193.9125.20.00.0Total 1397.3 974.0Table 2. Soil physical and chemical properties before establishment oflegumes and fallow in 2001.Properties Amount in soilSand (g kg -1 )Silt (g kg -1 )Clay (g kg -1 )TexturepH(H 2O)Organic carbon (g kg -1 )Total N (g kg -1 )Available P (g kg -1 )Exchangeable Ca (cmol kg -1 )Exchangeable Mg (cmol kg -1 )Exchangeable K (cmol kg -1 )470430100Silty loam5.25.370.45112.320.400.20Materials and MethodsStudy site characteristicsThe study was conducted in 2001 and 2002 at the Research Farm of theInstitute for Agricultural Research, Samaru, Zaria (11 o 11’N; 7 o 38’E; 680masl) in the northern Guinea savanna (NGS). The mean annual rainfall isabout 1061mm with a mono-modal pattern mostly concentrated betweenMay and September. The amount of rainfall received in each year ofcropping is presented in Table 1. The soil of the site is an Alfi sol (USDA)with silty loam surface texture. Selected physical and chemical propertiesof the surface soil (0-15cm) before commencement of study in 2001are shown in Table 2. The analysis showed that the soil had adequateavailable P (Bray P1) for legume cropping. The site had been left fallowfor more than three years and was vegetated mostly with Cyperus spp.and a few plants of Crotolaria retusa.