Summary
Summary
“La Conchuela” is a commercial olive orchard located about 10 km west of Córdoba, Andalusia, near the A-431 road. Over seven years, it served as a long-term experimental site to assess alternative soil management practices (specifically no-tillage and temporary spontaneous cover crops) to reduce soil erosion and runoff. Results showed that these practices significantly improved soil moisture retention, reduced erosion, and enhanced biodiversity, without compromising yields.
More recent studies confirm and expand these findings. Spontaneous cover crops have been shown to enhance carbon sequestration (up to 642 kg C ha⁻¹ yr⁻¹), nutrient retention (N, P, K), and support vegetation diversity. Ongoing research highlights their contribution to maintaining soil organic carbon and resilience under drought conditions, which are increasingly frequent in the Guadalquivir basin. The site is also referenced in broader Andalusian initiatives promoting regenerative olive farming, including the Living Lab Andaluz launched in 2024 to monitor soil health across olive groves in the region.
This case illustrates the long-term viability and scalability of green cover and no-tillage practices in Mediterranean tree crops, especially on rolling terrain vulnerable to erosion.
Photo gallery
Overview
Year of issue
2025
Project
NWRM
Implementation status
Completed
Contact
Fernanda Milans (IMDEA Water) in close cooperation with José Alfonso Gómez (IAS-CSIC) whose valuable contribution is acknowledged and very much appreciated.
Location of the project
The case study is located about 10 km west of Córdoba, Andalusia, near the A-431 road.
Country
Spain
NUTS2 Code
Andalucía
Sponge measures implemented in the case study
Minimum tillage
Cover crops
Objectives
Evaluate how different soil management practices could reduce runoff and soil erosion in sloping olive groves under Mediterranean conditions.
Quantify runoff and soil loss under three treatments: no-tillage with herbicide (NT), conventional tillage (CT), and temporary spontaneous cover crops (TSCC). A key goal was to demonstrate that TSCC could lower runoff coefficients to around 1–2%, compared to about 12% under NT. Soil erosion under TSCC was also expected to drop significantly, with values as low as 1.2 t/ha/year observed.
Other objectives included monitoring changes in infiltration, soil moisture, bulk density, and organic carbon. The project also aimed to assess the long-term feasibility of these practices for farmers, ensuring that they did not compromise olive yields.
Quantify runoff and soil loss under three treatments: no-tillage with herbicide (NT), conventional tillage (CT), and temporary spontaneous cover crops (TSCC). A key goal was to demonstrate that TSCC could lower runoff coefficients to around 1–2%, compared to about 12% under NT. Soil erosion under TSCC was also expected to drop significantly, with values as low as 1.2 t/ha/year observed.
Other objectives included monitoring changes in infiltration, soil moisture, bulk density, and organic carbon. The project also aimed to assess the long-term feasibility of these practices for farmers, ensuring that they did not compromise olive yields.
Involved partners
| Authority type | Authority name | Authority role | Comments | Authority responsibility |
|---|---|---|---|---|
| National water authority | INIA | Financing | National Institute for Agricultural and Food Research and Technology) | Supporting |
| Research institute / University | IAS-CSIC | Monitoring | Work has been carried out by researchers including J.A. Gómez and co-authors, affiliated with institutions such as IAS-CSIC (Institute for Sustainable Agriculture, part of CSIC, Córdoba) | Responsible |
Site Information
Climate Zone
Warm temperate dry
Precipitation
577.00 mm
Temperature (°C)
22.00 °C
Runoff
25.90 mm
Elevation range
144
Slope range
10-15%
Vegetation class
The main vegetation is a commercial olive grove (Olea europaea), managed in rows on sloping terrain. In the inter-row areas, different types of vegetative cover were tested: temporary spontaneous cover crops (TSCC), composed primarily of natural grasses and herbaceous species (e.g., Bromus, Lolium, Trifolium, Avena, Medicago).
WFD Ecological status
Moderate
WFD Chemical status
Failing to achieve good
Design and Implementation
Project scale
Micro
Project scale specifications
This project was implemented on a single experimental olive farm (La Conchuela) near Córdoba, covering a localized area of sloping land. It focused on site-specific soil and water conservation practices, such as cover cropping and no-tillage, with monitoring at the plot and hillslope scale. The interventions and measurements were confined to a field research setting, making it a clear example of a micro-scale natural water retention measure.
Project area
0,029 ha
Area subject to Land use change or Management/Practice change (ha)
0.03 ha
Constraints
Cover crops should be sown in early autumn after the onset of rains. Also the choice of the correct killing date to avoid water competition. They should be mown in early spring in order to prevent competition with the olive tree for water and nutrients. Cover crops can increase the probability of the development of pests an diseases associated to cover crops and increase the probability of wildfires. There are some technical problems related to the seed selection and its maintenance.
Favourable preconditions
The risk of competition for soil, water and nutrients between the tree and the cover crops is minimal in the initial years of the plantation (small and less trees density). Also in the case of irrigated groves that are adequately fertilized.
Financing
Information on Economic costs - income loss
Economic cost of increase in the use of herbicide and application cost
Compensations
No
Policy and Governance
Policy description
To date, 31% of the olive acreage in Andalusia is located on very steep terrains, on slopes of above 15%; 38% of the acreage is on moderate slopes, in the 7-15% range; the rest on slopes of under 7%. Traditional olive production is based on low tree densities weed control via frequent tillage and canopy size limited by pruning, to ensure the productivity and survival of the plantation in a limited rainfall environment. Olive production in the region has been associated with severe soil erosion problems accompanied by fertility depletion and loss of biodiversity.
Land ownership
The farm "La Conchuela" belongs to Francisco Natera, who has consistently supported the long-term experimental work conducted there.
Policy targets
Runoff control
Erosion Control
Part of a wider plan
No
Public consultation
No
Has contractual arrangements
No
Impacts and Monitoring
Monitoring System
Monitoring requirements
Monitoring was carried out by research teams from Spanish agricultural institutes and universities, focusing on soil, water, and vegetation parameters through regular field measurements.
Monitoring parameters
Throughout the long-term experiments, researchers monitored key hydrological and agronomic parameters including runoff volume, soil loss (erosion), soil moisture, soil organic carbon, bulk density, infiltration, and vegetation cover. Data collection involved installing bounded plots with runoff collectors, measuring rainfall, and assessing soil physical properties annually or seasonally. In more recent studies, they also evaluated aboveground biomass, carbon sequestration, and nutrient (N, P, K) content in spontaneous cover crops. These monitoring activities have provided robust data to evaluate the performance of different soil management strategies in olive groves on sloping land.
Maintenance
Maintenance requirements
The cover crops were maintained by mowing before the dry season, and the no-tillage areas were kept weed-free using herbicides.
Impact Assessment Methodology
Performance impact assessment method
Edge of Field/Plot
Performance impact estimation information
Rainfall, runoff and soil loss were recorded during 7 years under three different soil management systems: no tillage, conventional tillage and cover crops. The results of the three alternatives on soil properties and on runoff and sediment losses were thus compared.
Socio-economic Impacts
Direct benefits information
Economic benefits of improving productivity and avoided cost of improving the soil quality. Economic benefit from reducing tillage (reduce working hours, fuel consumption, machine fix cost).
Regenerative and organic practices on difficult terrains not only improved profitability but also enabled access to financial aid and enhanced environmental stewardship.
Regenerative and organic practices on difficult terrains not only improved profitability but also enabled access to financial aid and enhanced environmental stewardship.
Ancillary benefits information
CO2 sequestration, reduction in soil erosion, increase soil and water storage capacity and enhanced biodiversity
Biophysical impacts: Hydrology
Information on retained water
This is still to be defined in co-operation with practitioners. We are working with researchers on soil conservation measures on this water retention potential.
Information on increased water storage
Cover crops increase the infiltration rate and surface storage
Information on runoff reduction
Lower runoff coefficient in the Cover Crop treatment as compared to the Conventional Tillage and No-Tillage treatments. Higher runoff coeficient in the No-tillage system compare to the base line (Conventional Tillage). Average values (200-2006) runoff coefficient: NT: 11.9% / CT: 3.1% / CC:1.2%
Biophysical impacts: Biodiversity
Improved biodiversity
Yes
Information on improved biodiversity
Changing from bare soil managements (CC and NT) to the use of CC (where the amount of herbicide and frequency of tillage is reduced) increase the biodiversity of the agricultural system (De la Concha et al., 2007). Reducing tillage and heavy herbicide enhance the specturm ground flora and on insect populations. Moreover a permanent grass cover, managed by mowing or grazing, benefits soil and wildlife conservation (Beaufoy, 2001).
Biophysical impacts: Water & Soil Quality
Water quality overall improvements
Positive impact-WQ improvement
Information on water quality overall
In the cover crops treatment the water infiltrated more easily into the soil (under the protective plants) and at the same time the increased flow resistence dissipated the energy of the surface water. The aereal part of the plant intercepted part of the sediment particles carried by the water (Gómez et al., 2009)
Soil quality overall improvements
Positive impact-SQ improvement
Information on soil quality overall improvements
Positive impacto on soil quality under Cover Crops soil management (the capacity of plant covers in intercepting rainfall is a determining factor in the reduction of soil erosion, which subsequently avoids the development of impermeable crusts at the soil surface). No tillage treatment, bare soil with herbicide, does not benefit soil and water conservation compared to the traditional, Convemtional tillage, or the innovative, Cover crop.
Biophysical impacts: Others
Ecosystem impact climate regulation
Impact on GHGs (net emissions and storage) including soil carbon
Information on ecosystem impact climate regulation
Soil carbon sequestration in olives grove derived from the implementation of agricultural practices, mainly by reducing tillage (as in the case of CC management practices) significantly increase by up to 0.3 tons per hectare and year (Rodríguez et al., 2012). Changing from bare soil practices to the use of plant covers in combination with tillage or residual herbicide application, improves soil structure due to an increase in the organic matter (Gómez-Calero et al., 2009) thus allowing for the improvement of the carbon sink capacity of the olive agricultural system.
Information on ecosystem impact GHG soil carbon
Across five paired comparisons in Andalusian olive groves, sites with spontaneous cover crops stored 9.0 to 16.1 Mg C/ha more in the top 15 cm than non-TSCC sites, after more than eight years. In a survey of 46 olive groves, whole-farm cover crops achieved 642.1 kg C/ha/year, with biomass containing substantial N (~19.5 kg/ha/year), P (~2.48 kg/ha/year), and K (~24.3 kg/ha/year).
In broader Andalusian olive orchards, groundcovers plus pruning residues increased SOC by 0.02 to 3.02 Mg C/ha/year over four seasons (to 30 cm depth).
In broader Andalusian olive orchards, groundcovers plus pruning residues increased SOC by 0.02 to 3.02 Mg C/ha/year over four seasons (to 30 cm depth).
Lessons Learned
Key lessons
The study shows that the use of a cover crop can be a simple, feasible soil and water conservation practice in olive groves on rolling lands in the region. A key factor in its practical use is to establish it early enough to protect the soil in the critical initial years of the grove, when most of the soil is unprotected by the small olive canopy. The no-tillage treatement, bare soil with herbicide, does not benefit soil and water conservation.
Practices are low-cost and compatible with yields
The techniques tested required minimal additional inputs and did not reduce olive yields. Farmers could benefit from reduced fuel use and maintenance, though herbicide costs may rise under no-tillage systems.
Monitoring is essential for understanding impacts
The project’s long-term, well-structured monitoring allowed precise measurement of hydrological and agronomic responses. It also built scientific evidence for wider replication.
No-tillage without cover crops increases risks
Plots with no-tillage but no ground cover (kept bare with herbicides) produced the highest runoff and erosion. This shows that no-tillage alone, without vegetative protection, can have negative impacts.
Practices are low-cost and compatible with yields
The techniques tested required minimal additional inputs and did not reduce olive yields. Farmers could benefit from reduced fuel use and maintenance, though herbicide costs may rise under no-tillage systems.
Monitoring is essential for understanding impacts
The project’s long-term, well-structured monitoring allowed precise measurement of hydrological and agronomic responses. It also built scientific evidence for wider replication.
No-tillage without cover crops increases risks
Plots with no-tillage but no ground cover (kept bare with herbicides) produced the highest runoff and erosion. This shows that no-tillage alone, without vegetative protection, can have negative impacts.
Drivers
| Driver type | Driver role |
|---|---|
| Balancing different objectives | Main driver |
Success factors
| Success factor type | Success factor role |
|---|---|
| Specific incentives for stakeholder involvement | Main factor |
Transferability
This measure is highly transferable to other sloping Mediterranean olive groves, especially under rainfed conditions. However, success depends on local slope, soil type, rainfall, and how cover crops are managed. Care must be taken to avoid bare soil under no-tillage, and herbicide use should be minimized or replaced by mowing to preserve biodiversity and soil health.
Sources
Sources