Effects of different tillage system on arbuscular mycorrhizal fungal propagules and physical properties in a Mediterranean agroecosystem in central Chile

Arbuscular mycorrhizal (AM) fungi improve soil quality by increasing soil structure stability through the glomalin (glomalin related soil protein, GRSF) production, but diverse tillage systems can differentially affect AM activity and the consequential GRSP content in soil. The aim of this study was to evaluate the effect of no-tillage (NT) and conventional tillage (CT) on AM fungal propagules (spore density, total and active fungal hyphae), GRSP content, and its relationship with some physical-chemical soil properties in a Mollisol from Central Chile. For this study, two plots managed for 6 and 10 years under NT (Nit; and NT10), were compared with another plot maintained under CT management. In all cases a continuous spring wheat (Triticum turgidum L.)-maize (Zea mays L.) rotation was established. The number of mycorrhizal propagules, total soil carbon (T-C) and GRSP content in NT6 was higher compared to CT and NT10. This trend was also observed for water stable aggregates (WSA) and water drop penetration time. Significant relationships were found between total mycelium and GRSP (r = 0.58, p < 0.05), GRSP, and WSA (r = 0.66, p < 0.01) and between GRSP and T-C (r = 0.60, p < 0.05), suggesting an active role of AM fungi and GRSP on soil aggregation, particularly under NT6 management. In addition, the long-term NT management (NT10) produced a decrease in the parameters here assayed which suggest the application of one moderate plowing when parameters such as T-C and/or GRSP show a decrease in long-term programs of reduced or NT management applied in medium/heavy soils. (C) 2011 Elsevier B.V. All rights reserved.