Water Related Properties to Assess Soil Quality in Two Olive Orchards of South Spain under Different Management Strategies

Abstract

Soil quality is usually assessed through the measurement of selected soil properties. However, in spite of the diversity of the chosen properties, use of the soil water retention curve, like the pressure head or the specific water capacity at the inflection point, provides relevant information of degradation or improvement of soil. The main aim of this study was to evaluate the methods based on these indices in the evaluation of short-term changes of olive cropped soils under typical Mediterranean agricultural conditions. For this reason, soil properties (bulk density, hydraulic conductivity, aggregates stability, and organic matter content) were measured in a short-term trial settled in two olive orchards under different soil managements: tillage and cover crop. Several sampling areas were also distinguished: (i) along the inter tree row and under the canopies’ projection and (ii) at 0–10 cm and 10–20 cm depth. In addition, water retention curves were determined and fitted using two models (van Genutchen’s and Kosugi’s) in order to obtain the inflection point and therefore the S index. This index is the maximum value of the slope of the soil water retention curve and is related to soil quality. At the two sites, changes in soil management, even after a brief period of two years, had a relatively quick effect, especially in organic matter content along the inter tree row. The use of indices based on soil water retention curves helps to detect soil degradation or improvement changes. Future research, including the inclusion of more soil types and longer time periods, might lead to the development of more refined tools for the assessment of soil health.

Differences in Mineral Phase Associated Soil Organic Matter Composition due to Varying Tillage Intensity

“…Land use changes triggered significant differences in the SOC content of the bulk soil (Table 1) even in this short period, which was also presented by Guzmán et al [47]. The highest value was found under the NF (40.60 ± 0.61 mg g −1 ), whereas under PT, the SOC content decreased to 10.50 ± 0.02 mg g −1 .…”

Geomorphodynamics in Argan Woodlands, South Morocco

“…The infiltration measurements have shown a significant difference between tree and intertree areas for both unsaturated and saturated hydraulic conductivity, as well as infiltration rates, indicating a better infiltrability into the soil in vegetation patches [80,87]. Lichner et al [88] noted high K sat values in forest soils due to the greater presence of macropores, yet found the lowest K h values for forest sites possibly due to a higher water repellency caused by the coating of soil particles by pine-needle waxes.…”

Estimation of Soil Loss Tolerance in Olive Groves as an Indicator of Sustainability: The Case of the Estepa Region (Andalusia, Spain)

“…According to these results, there was a positive relationship between erosion and dry bulk density, leading to a greater soil compaction [50,59]. A higher erosion level is often observed in areas where tillage and management practices increase soil compaction, resulting in high bulk density and reduced soil porosity [66,67]. Consequently, in the case of integrated rainfed management and severe erosion, an increase of 20.72% in the compaction of soils and decrease of up to 12.44% in the porosity was observed with respect to the values of rainfed integrated olive groves with null erosion, being a variable that contributes to mitigating soil loss by allowing rainwater infiltration into the subsoil [16,68].…”