Abstract

IGLESIAS, Julio Osvaldo; GALANTINI, Juan Alberto  and  VALLEJOS, Adrian. Estabilidad de agregados de un Argiustol del SO bonaerense con diferentes sistemas de labranza. Cienc. suelo [online]. 2017, vol.35, n.2, pp.189-203. ISSN 1850-2067.

Land mismanagement leads to degradation of soil structure, affecting the ecosystem and jeopardizing the productive potential of soils. Tillage systems modify carbon content and distribution, and hence influence the structural stability of soils. This study discusses the effect of no tillage (NT) and conventional tillage (CT) on aggregate-size distribution and carbon content in comparison with an uncultivated or natural soil (Nat).The soil samples were taken to the 0-5 and 5-10 cm depths. They were analyzed for total organic carbon, coarse particulate organic carbon, fine particulate organic carbon and mineralassociated organic carbon. The content of total carbohydrates and soluble carbohydrates was determined. The aggregates were isolated by dry- and wet-sieving and their stability was calculated. All organic carbon forms within the 0-5 cm depth decreased as soil disturbance was higher, whereas no differences were observed in the 5-10 cm depth between NT and CT. The fraction of the dry-sieved aggregates smaller than 1 mm in the 0-5 cm depth turned out to be the most sensitive to tillage; it increased in the order Nat (17.3%)< NT (24.9%)< CT (34.6%), following the same tendency as aggregate stability. Tillage reduction tended to increase the amount of aggregates larger than 2.8 mm, with values of 66 (Nat), 57 (NT) and 37% (CT). Soluble carbohydrate content in the various sizes of the aggregates isolated by dry-sieving followed the same tendency as aggregate stability in aggregates larger than 2.8 mm and smaller than 1 mm. Aggregate stability was associated with the management-sensitive fraction smaller than 1 mm.

Keywords : Aggregates; Organic carbon; Organic fractions; Soil cementing agents.

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