Ca-amendement and tillage: medium term synergies for improving key soil properties of acid soils. Soil and tillage research, 134: 195-206

Ca-amendments are routinely applied to improve acid soils, whilst no-tillage (NT) has been widely recommended in soils where traditional tillage (TT) has led to losses of organic matter. However, the potential interactions between the two treatments are only partially known. Our study was conducted on an annual forage crop agrosystem with a degraded Palexerult soil located in SW Spain, in order to assess if the combination of NT plus a Ca-amendment provides additional benefits to those of their separate use. To this end we analysed the effects of four different combinations of tillage and Ca-amendment on selected key soil properties, focusing on their relationships. The experimental design was a split-plot with four replicates. The main factor was tillage (NT versus TT) and the second factor was the application or not of a Ca-amendment, consisting of a mixture of sugar foam (SF) and red gypsum (RG). Soil samples were collected from 3 soil layers down to 50 cm after four years of treatment (2009). The use of the Ca-amendment improved pH and Al-toxicity down to 25 cm and increased exchangeable Ca2+ down to 50 cm, even under NT due to the combined effect of SF and RG. Both NT and the Ca-amendment had a beneficial effect on total organic carbon (TOC), especially on particulate organic carbon (POC), in the 0–5 cm layer, with the highest contents observed when both practices were combined. Unlike NT, the Ca-amendment failed to improve soil aggregation in spite of the carbon supplied. This carbon was not protected within the stable aggregates in the medium term, making it more susceptible to mineralization. We suggest that the fraction of Al extracted by oxalate from solid phase (AlOxa-Cu-K) and the glomalin-related soil proteins (GRSPs) are involved in the accumulation of carbon within water stable aggregates, probably through the formation of non-toxic stable Al-OM compounds, including those formed with GRSPs. NT alone decreased AlK in the 0–5 cm soil layer, possibly by increasing POC, TOC and GRSPs, which were observed to play a role in reducing Al toxicity. From our findings, the combination of NT and Ca-amendment appears to be the best management practice to improve chemical and physical characteristics of acid soils degraded by tillage.

ROPAX 1200 pasajeros, 5000 metros lineales para trailers y 11500 TPM.

Ferry de día - ROPAX para 1200 pasajeros distribuidos en 300 camarotes cuádruples con aseo y espacios públicos a razón de 3.5 m2 por persona. Tiene una capacidad de carga de 5000 metros lineales para trailers y 230 metros lineales para coches (carga simultánea), para un total de 11500 toneladas de peso muerto. El buque contará con portalón de popa y proa (double enter). La velocidad en pruebas será de 22 nudos al 85% MCR y se tomará un margen de mar del 15%. La autonomía será de 3000 millas al 85% MCR. Clasificado por Lloyd's Register. Reglamentos seguidos: MARPOL, SOLAS, Convenio de Lineas de Carga de 2005 y Acuerdo de Estocolmo.