Z. Kabir et al., SEASONAL-CHANGES OF ARBUSCULAR MYCORRHIZAL FUNGI AS AFFECTED BY TILLAGE PRACTICES AND FERTILIZATION - HYPHAL DENSITY AND MYCORRHIZAL ROOT COLONIZATION, Plant and soil, 192(2), 1997, pp. 285-293
The influence of tillage practices on native arbuscular mycorrhizal fu
ngi (AMF) was studied in two, consecutive years in eastern Canada, in
two 11 year-old long-term tillage-fertilizer experimental field soils,
a sandy loam and a clay, growing corn in monoculture. The three tilla
ge practices were: 1)conventional tillage (CT; fall plowing plus sprin
g disking), reduced tillage (RT; spring disking) and no-till (NT). The
corn crop received either inorganic (N and K) or organic (liquid dair
y manure) fertilizers. Mycorrhizal hyphal density was estimated from s
oil samples obtained in early spring (before disking), at the 12-14 le
af stage, at silking, and at harvest. The percentage of corn root colo
nization by AMF at the 12-14 leaf stage, at silking and at harvest was
also determined. The sandy loam was sampled over two consecutive seas
ons and the clay soil over one season. Densities of total and metaboli
cally active soil hyphae, and mycorrhizal root colonization were signi
ficantly lower in CT soil than in RT and NT soil. Lowest soil hyphal d
ensities were observed in early spring. The levels of intra-and extrar
adical fungal colonization always increased from spring to silking and
decreased thereafter. Spring disking had only a small and transient n
egative effect on hyphal abundance in soil. Fertilization did not infl
uence mycorrhizal colonization of corn or abundance of soil hyphae in
the sandy loam soil, but in the clay soil metabolically active hyphae
were more abundant with manure application than with mineral fertiliza
tion. In 1992, in both soils different tillage systems had same grain
yield, however, in 1993, corn yield was higher in NT compared to CT sy
stem.