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Influence of arbuscular mycorrhizae on soil P dynamics, corn P-nutrition and growth in a ridge-tilled commercial field

2008; Canadian Science Publishing; Volume: 88; Issue: 3 Linguagem: Inglês

10.4141/cjss07024

1918-1841

Christine Landry, Chantal Hamel, Anne Vanasse,

Soil Carbon and Nitrogen Dynamics

Ridge-tilled corn (Zea mays L.) could benefit from arbuscular mycorrhizal (AM) fungi. Under low soil disturbance, AM hyphal networks are preserved and can contribute to corn nutrition. A 2-yr study was conducted in the St. Lawrence Lowlands (Quebec, Canada) to test the effects of indigenous AM fungi on corn P nutrition, growth, and soil P in field cropped for 8 yr under ridge-tillage. Phosphorus treatments (0, 17, 35 kg P ha -1 ) were applied to AM-inhibited (AM I ) (fungicide treated) and AM non-inhibited (AM NI ) plots. Plant tissue and soil were sampled 22, 48 and 72 days after seeding (DAS). P dynamics was monitored in situ with anionic exchange membranes (P AEM ) from seeding to the end of July. AM NI plants showed extensive AM colonization at all P rates. At 22 DAS, AM I plants had decreased growth in the absence of P inputs, while AM NI plants had higher dry mass (DM) and P uptake in unfertilized plots. The P AEM was lower in the AM NI unfertilized soils in 1998 and at all P rates in 1999, indicating an inverse relationship between P uptake and P AEM . At harvest, grain P content of AM NI plants was greater than that of AM I plants. In 1998, only AM I plants had decreased yield in the absence of P fertilization. In 1999, AM NI plants produced greater grain yield than AM I plants at all P rates. AM fungi improve the exploitation of soil P by corn thereby maintaining high yields while reducing crop reliance on P inputs in RT. Key words: Arbuscular mycorrhizae, ridge-tillage, soil P dynamics, corn, P nutrition