Abstract
Maize growth, root colonization by arbuscular mycorrhizal fungi (AM fungi) and by non-AM fungi, and soil properties were studied on a field of Humic Andosol in 1998. The field had been tilled with different intensities since November 1997. A plot was minimum-tilled with a rotary tiller (MT) and the other plot was tilled with a moldboard plow and disc-harrowed (T). The least-squares fit of cubic or quadratic surfaces to the data collected from 9-100 locations in each plot clarified that the dry weight of maize shoot and root colonization by fungi showed a clear spatial variability in the area of 17.5 m × 25 m. Inverse spatial variability patterns between AM fungi and non-AM fungi in both MT and T indicated that there was an apparent competition between them in colonizing maize roots. Maize growth showed a spatial variability pattern similar to that of AM fungal organs, in particular in T. This suggested that the spatial variability pattern of maize in T was more affected by the relationship between AM fungi and non-AM fungi. Site-specific control of AM fungal infection for improving maize growth in small fields was discussed.
