Figure 2: Nodules dry weight (mg/plant) as affected by year × cropping system × cowpea variety interactions effects ( ) at flower buds and bloom stage at Cinzana Agronomic Research Station, 2007 and 2008. Y1: year 1 (2007); Y2: year 2 (2008), S1: alternate rows intercropping (1 row millet/1 row cowpea), S2: inter hills intercropping (2 hills millet/1 hill cowpea), S3: cowpea sole crop, cowpea varieties: IT89KD-374, CZ1-94-23-1, and CZ11-94-5C.