Soil aggregation and organic carbon protection in a no-tillage chronosequence under Mediterranean conditions

• DOI: 10.1016/j.geoderma.2012.10.022
• Publication Date: 2012-11-17T10:38:20Z
• Authors: D. Plaza-Bonilla; C. Cantero-Martínez; P. Viñas; J. Álvaro-Fuentes
• Keywords: Chronosequence; Soil carbon; Agroecosystem; Conventional tillage

Peer reviewed<br/>This research was supported by the Comision Interministerial de Ciencia y Tecnologia of Spain (AGL 2004-07763-C02-02 and AGL 2010-22050-C03-01). D. Plaza-Bonilla was awarded with a FPU fellowship by the Spanish Ministry of Education. Jorge Álvaro-Fuentes acknowledges the Consejo Superior de Investigaciones Científicas (CSIC) for his contract within the “Junta para la Ampliación de Estudios” (JAE-DOC) programme co-financed by the European Social Fund.<br/>Low-intensity soil management systems like no-tillage (NT) are being increasingly accepted as an essential part of sustainable farming systems. The objective of this work was to study the effects of NT maintenance over time on soil aggregation and soil organic carbon (SOC) protection on a semiarid Mediterranean agroecosystem. A NT chronosequence was established with five phases: (i) conventional tillage (CT); (ii) NT for 1 year (NT-1); (iii) NT for 4 years (NT-4); (iv) NT for 11 years (NT-11) and (v) NT for 20 years (NT-20). N fertilization was based on pig slurry for the whole experimental area. Soil samples were collected from four depths (i.e., 0–5, 5–10, 10–20, 20–30 cm). Dry and water-stable aggregates, SOC concentration and C concentration of water-stable aggregates were measured. SOC concentration reached its maximum value after 11 years under NT. However, the differences between NT phases were only found in the 0–5 cm soil depth. In soil surface (i.e., 0–5 cm), water-stable large macroaggregates (2–8 mm) were 0.02, 0.12, 0.32 and 0.31 g g− 1 dry soil for the NT-1, NT-4, NT-11 and NT-20 phases, respectively. C concentration of microaggregates increased in relation with the number of years under NT. SOC and water-stable macroaggregate stratification were greatest with the increase in the years under NT, emphasizing the close relationship between SOC and aggregation. In Mediterranean semiarid agroecosystems, the increase in the proportion of stable macroaggregates and the enrichment of C concentration within microaggregates are two main mechanisms of SOC protection when NT is maintained over time.<br/>24 Pags., 4 Tabls, 3 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/00167061<br/>