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

209Grain yield of maize following soybean genotypesThe pattern of variation in maize grain yield across previous Ptreatments was similar to that of soybean in the three locations. In2002, mean grain yields of maize following soybean within 0P plots(1664 kg ha -1 ) and TSP plots (1634 kg ha -1 ) were signifi cantly higherthan the 1374 kg ha -1 obtained from the previous RP plots at Fashola.The grain yield (kg ha -1 ) from the specifi c soybean genotype plotsranged from 1236 to 2063 within the previous 0P treatment, from963 to 1837 within the previous RP treatment, and from 1239 to1933 within the previous TSP treatment. The corresponding maizegrain yield from the maize-after-maize plots was 1501 kg ha -1 for 0P,1025 kg ha -1 for RP, and 1268 kg ha -1 for TSP. At Davié, maize grainyields across soybean genotype plots were relatively lower with thedifferences between mean values (kg ha -1 ) of the previous 0P (1217),RP (1244), and TSP plots (1251) not being statistically signifi cant.Similarly, there were little differences between grain yields of maizefollowing soybean genotypes (data not shown).The fresh application of 15 kg P ha -1 in 2003 to previous (2002) 0Pplots at Shika increased mean maize yields across soybean genotypessubstantially (up to 178%), whereas the residual effect of the 2002 Papplication on mean grain yield was only 15% for the RP plots and25% for the TSP plots. Also, maize yields from previous RP and TSPplots were signifi cantly (P ≤ 0.05) higher than yields from the previous0P plots (Table 6). These apparent benefi ts from previous P applicationwere however reduced at Fashola and Davié. The mean maize grainyields from the 15P plots were signifi cantly higher than those of 0Pplots at Fashola, while increases due to previous RP application werenot signifi cantly different. At Davié, the mean grain yield from the 15Pplots was signifi cantly higher than those of previous 0P plots but nothigher than those of the TSP and RP treatments (Table 6).VAM colonization of root of maize after soybeanIn 2002, mean VAM colonization (%) of maize roots across 2001soybean and maize plots within 0P treatments was signifi cantly higherthan mean values obtained in previous RP plots (16), and TSP plots(37) at Fashola. Also, at Davié, the mean VAM colonization (%) ofmaize from the previous 0P plots (39) was signifi cantly higher thanthose of the previous RP (9), and TSP (21) plots. Differences amonggenotypes were, however, not consistent across P treatments andlocations (data not shown).Similarly, the mean VAM of maize roots from the previous 2002soybean plots were highest (33–40%) in the previous 0P plots andlowest (3 –5%) in the 15P plots and this was consistent at all the locations(Table 7). Surprisingly, VAM colonization was more suppressedwithin the previous RP plots than in the previous TSP plots. The VAM