Ecological and Economic Sustainability in Olive Groves with Different Irrigation Management and Levels of Erosion: A Case Study

Abstract

In the last 50 years, both the agricultural labour force and irrigated land area have increased almost eightfold in Spain. The main objective of irrigation, in the short term, is to increase agricultural production. However, in the long term, the environmental externalities of irrigation and its direct relationship with soil erosion processes are more uncertain and still poorly studied. In this study, in an olive-growing region of Andalusia, Spain, the variation of several soil parameters related to irrigation and erosion levels was analysed. The results showed that irrigation, while increasing the productive level of the olive groves, entails a progressive alteration of the soil, modifying physical aspects (greater compaction and humidity of the soil together with lower gravel content, porosity and soil weight) and chemical aspects (reduction of the organic matter of the soil and the content of nitrates) that can aggravate the consequences of the erosive processes. In the long term, the productive benefit attributed to irrigation could be unsustainable from an ecological and, consequently, economic point of view. In addition, the lack of sustainability of olive irrigation agroecosystems could be exacerbated by the future restrictive impacts of climate change on water resources in Mediterranean environments. This situation demands spatial planning and alternative management based on soil conservation and rational and efficient forms of irrigation to ensure the sustainability of olive groves and their economic viability.

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

“…Chemically, decreases of 7.60% and 62.43% were observed for pH and organic matter of the soil, respectively, as the erosive level of the rainfed plots increased (i.e., from null to severe), resulting from the loss of cations due to runoff. These observations were greatest in irrigated plots [16,69,70]. Additionally, the implementation of irrigation increased these differences, assuming a decrease of between 0.24 to 0.63% of pH and 18.11 to 23.74% of organic matter content in the moderate and severe erosion levels compared to the values estimated for rainfed olive groves.…”

“…Comparing these average values to the soil depth of the rainfed integrated plots with null erosion resulted in proportional decreases in the weight of soil per unit area, due to the acceleration of soil loss from the increase of erosive processes [33]. In irrigated olive crops, the density of the soil increased by up to 15%, with decreases in the weight of the soil by up to 15.13% with respect to the rainfed integrated olive grove, due to the implementation of irrigation as a practice of agrarian intensification leading to an increase in soil loss from runoff [62,69]. On the other hand, soil moisture with hydric incorporation to the crop was also higher, presenting plots with moderate and severe erosion with 63.64% and 56.73% more water content, compared to rainfed plots and equivalent erosion.…”

“…Several studies mention the negative impact of irrigation on erosion, especially through increasing surface runoff and contributing to the infiltration of pollutants (herbicides and pesticides) into groundwater [13,69]. Other studies show that localized and deficit irrigation avoids or minimizes these impacts [47].…”

A Comparative Analysis of Soil Loss Tolerance and Productivity of the Olive Groves in the Protected Designation of Origin (PDO) Areas Norte Alentejano (Portugal) and Estepa (Andalusia, Spain)

“…Although the majority of these systems are rainfed, 10% of the olive area depends on deficit/drip irrigation, with farms vastly managed under integrated models. Additionally, this region presents an incipient development of organic rainfed olive groves, where only the use of organic fertilisers is allowed (i.e., 500 ha) [6,20,40] PDO Norte Alentejano currently includes three types of olive grove management models, depending on the density of planting and the energy inputs applied to the crop: (a) traditional management, (b) integrated management, and (c) intensive management. The olive groves belonging to this region are located in areas with slopes of up to 15% and are considered to be plain olive groves where the use of agricultural machinery is allowed [19].…”

Using Machine Learning-Based Algorithms to Analyze Erosion Rates of a Watershed in Northern Taiwan

“…In the field of soil erosion modeling, there have been many studies carried out to estimate soil erosion using models such as USLE [9,19], SWAT [20,21], WEPP [22,23], WaTEM/SEDEM [24,25], and EUROSEM [26]. However, there has been no application of ML algorithms to estimate soil erosion except for in our previous work [27], in which we used Decision Tree (DT), Random Forest (RF), and Multiple Regression (MR) to create ML models to predict the soil erosion depths (rates).…”