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Table 1. Average biomass and grain yield of maize and faba bean in monoculture and intercropping for 4 yr from 2003 to 2006 (Field Study 1)

Crop Cropping system Average for 2003–2006, kg/ha % increase ANOVA, variable F P

Grain yield

    Maize M(C) 12,813^c 0 Cropping 54.1 <0.0001

M&F(C) 18,905^a 49 Year 25.2 <0.0001

M&F(R) 17,363^b 37 Cropping x year 1.5 0.2133

    Faba bean F(C) 4,291^b 0 Cropping 9.6 0.0010

M&F(C) 5,242^a 22 Year 48.2 <0.0001

M&F(R) 5,716^a 29 Cropping x year 2.9 0.0308

Above-ground biomass

    Maize M(C) 26,918^c 0 Cropping 53.9 <0.0001

M&F(C) 39,993^a 49 Year 31.2 <0.0001

M&F(R) 36,989^b 38 Cropping x year 3.0 0.0254

    Faba bean F(C) 10,379^b 0 Cropping 9.0 0.0014

M&F(C) 12,659^a 22 Year 64.0 <0.0001

M&F(R) 13,003^a 21 Cropping x year 4.3 0.0053

M(C), continuously cropped maize; F(C), continuously cropped faba bean; F&M(C), faba bean and maize continuously intercropped with the same crop on the same strips of land; F&M(R), faba bean and maize rotationally intercropped with each crop rotated to the other crop's strips each year (see Methods). Each treatment had three replicates, and all plots received 225 kg/ha N fertilizer and 40 kg/ha P₂O₅ fertilizer. Values in the same column within the same crop followed by different superscript letters are significantly different (P < 0.05) based on least-squared difference multiple comparison. The percent increase values are (M&F-M)/M x 100 or (M&F-F)/F x 100. The ANOVA was a two-way analysis with cropping systems and year as variables, where the df is 2 for the cropping system, 3 for the year, and 6 for the interactions between cropping and year.