The influence of cover crops and tillage on water and sediment yield, and on nutrient, and organic matter losses in an olive orchard on a sandy loam soil

Abstract

Is the cover crop practice suitable for soil and water conservation in olive tree cropping? Rainfall, runoff, sediments, nutrient and organic carbon losses from 8 x60-m plots were measured during four hydrological years (2002 to 2007) in a field trial, in which two different soil management systems were used to confirm this hypothesis: a cover crop, (CC), and conventional tillage, (CT). The plots were located in a private olive tree farm on a sandy-loam soil, near Seville, southern Spain. The cover crop, as compared to conventional tillage, efficiently reduced runoff and sediment yield down to tolerable levels, 5.68% of the rainfall being converted to runoff, and the soil loss reaching 0.04 kg m-2 year-1 , as the average of four years. Additionally, in the cover crop treatment, the values of the nutrient export either dissolved in the runoff water or adsorbed in the sediment, were lower than the analogous values of the conventional tillage treatment: 0.631 and 0.065 kg m-2 year-1 of organic carbon and nitrogen, respectively, 0.175 and 0.0333 kg m-2 year-1 of soluble K and P, respectively, and 0.010 and 0.002 kg m-2 year-1 of available K and P, 2 respectively. The adoption of a cover crop as a soil management practice can be a feasible way to reach sustainability in many olive-cropped soils of southern Spain, although this method is not always easy to implement due to technical problems such as seed selection, its maintenance, and the choice of the correct killing date to avoid water competition. These difficulties could explain the slow rate of its adoption by many farmers. Further exploration of these aspects is required, as well as a specific agricultural extension campaign.

Temporal stability of electrical conductivity in a sandy soil

“…In areas with weakly developed soils, such as the Setenil region, the rugged relief often leads to partial loss of the topsoil layer (Ibañez et al, 2015;Symeonakis et al, 2014). This is a natural process aggravated by certain agricultural practices (eg tillage) (Gómez et al, 2009;Keesstra et al, 2016;Taguas and Gómez, 2015;Vanwalleghem et al, 2011), leading to outcropping of the bedrock and to the appearance of localised zones where the humus-rich horizon rarely exceeds 0.1 m. The climate is Mediterranean, with a mean annual precipitation of 700 mm, where 75% of the rainfall occurs from October to May. The grove is under minimum tillage and weeds are controlled with chemical herbicides.…”

Soil management in rainfed olive orchards may result in conflicting effects on olive production and soil fertility

“…Tillage damages the roots of the trees which may represent a great loss of carbohydrates which are then required to restore them. Additionally, regular tillage encourages soil erosion and the loss of nutrients through runoff (Gómez et al, 2009). Furthermore, tillage also reduces soil organic matter (Pastor, 2008;Aranda et al, 2011).…”

“…Cover cropping is currently the most effective practice for soil protection and maintaining the sustainability of the cropping system, as it can reduce soil erosion (Martínez et al, 2006;Pastor, 2008;Gómez et al, 2009) and increase soil organic matter and improve many other physical, chemical and biological properties of the soil compared with frequent tillage or non-covered treatments (Castro et al, 2008;Moreno et al, 2009;Ramos et al, 2010Ramos et al, , 2011. Cover crops, however, compete for resources with the trees, which can lead to a reduction in crop productivity (Hornig & Bünemann, 1993;Lipecki & Berbeç, 1997;Silvestri et al, 1999;Gucci et al, 2012).…”

Efecto de técnicas de agricultura de conservación en la respiración del suelo en plantaciones de almendro en la región mediterránea (SE, España)

“…En primer lugar, se reduce la pérdida de materia orgánica adsorbida a los sedimentos al reducir la erosión hídrica (Durán et al 2012;Francia et al 2006;Gómez et al 2009,). El segundo motivo está relacionado con el incremento del contenido de materia orgánica al ser mayor la cantidad de residuos vegetales que se incorporan al suelo Nieto et al 2012;Ramos et al 2010).…”