INFLUENCE OF COMPACTION FROM WHEEL TRAFFIC AND TILLAGE ON ARBUSCULAR MYCORRHIZAE INFECTION AND NUTRIENT-UPTAKE BY ZEA-MAYS

Interactive effects of seven years of compaction due to wheel traffic and tillage on root density, formation of arbuscular mycorrhizae, abov e-ground biomass, nutrient uptake and yield of corn (Zea mays L.) were measured on a coastal plain soil in eastern Alabama, USA. Tillage and soil compaction treatments initiated in 1987 were: 1) soil compaction from tractor traffic with conventional tillage (C,CT), 2) no soil com paction from tractor traffic with conventional tillage (NC,CT), 3) soi l compaction from tractor traffic with no-tillage (C,NT), and, 4) no s oil compaction from tractor traffic with no-tillage (NC,NT). The study was arranged as a split plot design with compaction from wheel traffi c as main plots and tillage as subplots. The experiment had four repli cations. In May (49 days after planting) and June, (79 days after plan ting), root biomass and root biomass infected with arbuscular mycorrhi zae was higher in treatments that received the NC,NT treatment than th e other three treatments. In June and July (109 days after planting), corn plants that received C,CT treatment had less above-ground biomass , root biomass and root biomass infected with mycorrhizae than the oth er three treatments. Within compacted treatments, plants that received no-tillage had greater root biomass and root biomass infected with my corrhizae in May and June than plants that received conventional tilla ge. Corn plants in no-tillage treatments had higher root biomass and r oot biomass infected with mycorrhizae than those in conventional tilla ge. After 7 years of treatment on a sandy Southeastern soil, the inter active effects of tillage and compaction from wheel traffic reduced ro ot biomass and root biomass infected with mycorrhizae but did not affe ct plant nutrient concentration and yield.