Relación entre densidad de hifas de hongos micorrizógenos arbusculares y producción de glomalina con las características físicas y químicas de suelos bajo cero labranza

Abstract

Reduced and no-tillage (NT) are the main management practices contributing to the stability of agricultural land. We investigate the relationships between some arbuscular mycorrhizal characteristics such as extraradical hyphal density and the production of glomalin, an insoluble glycoprotein exuded by arbuscular mycorrhizal hyphae, with physical and chemical properties of an alfisol under NT. Soils at different depths (0-50; 50-100 and 100-200 mm) were collected from plots with four (4 NT), seven (7 NT) and twenty (20 NT) years managed under NT system. Soil from a natural prairie was also sampled as a control for comparison of management agricultural systems. Data obtained showed that pH, available-P, total P and organic carbon increased according to the time under NT. The percentage of porosity severely decreased in the 20 NT soil especially at two upper horizons. The percentage of water stable soil aggregates was similar in all the soils with exception of 7 NT soil probably due to Lupinus albus was the preceding crop. Total and easily extractable glomalin increased according to the years under NT representing about the 0,36% of organic matter in the upper layer of the 20 NT soil. Close relationships were found between total and easily extractable glomalin content (r² = 0.97), organic C and total glomalin (r² = 0.96), pH and mycorrhizal hyphal density (r² = 0.72), mycorrhizal hyphal density and total P (r² = 0.74). No clear relationships between soil water stable aggregates and glomalin concentration or hyphal density were observed suggesting that aggregation and stabilization in those soils could be governed by other type of interactions