Where Does Your Olive Oil Come From? Part 3 of 5

The organic movement represents a crucial step away from synthetic pesticides and fertilizers, addressing many of the concerns we explored in Part 2. And the evidence suggests it often helps. A study of 41 organic and 49 neighbouring conventional olive farms in Andalusia found that organic soils generally had more organic matter and higher microbial diversity. [1] Another study in the province of Córdoba found that the shift to organic olive farming brought less tillage, more living ground cover and a lower risk of erosion. [2]

Yet an organic label alone doesn’t guarantee living soil – or olive oil rich in the protective compounds that make it healthful. That is the paradox.

What the Organic Label Promises

European organic rules set out the right principles. Organic crops must be grown in living soil, and organic growers are expected to use cultivation practices that maintain or increase soil organic matter, enhance soil stability and biodiversity, and prevent compaction and erosion. [3]

But principles are not measurements. Organic certification verifies how a farm is managed and which inputs it uses. It does not require growers to measure the life in their soil, or the phenolic content of their oil. Two groves can carry the same organic label while producing very different soil – and very different olive oil.

The Tillage Trap

Weed control is where many organic growers face their hardest choice. Without herbicides, the plough is often the default – and as Part 2 showed, tillage breaks down the soil structure and fungal partnerships that support the tree.

Alternatives exist, and they needn’t cost yield. A study of organic olive farms in Andalusia compared weed control by shallow spring tillage with mechanical mowing. Both produced similar yields, on par with nearby conventional rainfed groves. [4]

What happens below ground reaches the bottle. In an Italian high-density olive orchard, five years of natural ground cover left the topsoil with more than twice the pore space of tilled soil, better water infiltration and more organic carbon. Oils from the covered plots had slightly higher phenolic concentrations. [5] In a Spanish trial, tillage lowered fruit maturity and produced oil with lower polyphenol content than the groundcover treatments. [6]

There are trade-offs. In the Italian orchard, trees under cover were smaller and yielded less than tilled trees. [5] Ground cover must be managed so that it supports the trees rather than competing with them.

The Input Substitution Model

Many organic systems operate on an input substitution model – replacing synthetic fertilizers with organic ones, and synthetic pesticides with organic alternatives. This reduces chemical residues, but it doesn’t necessarily rebuild the living systems that make external inputs less necessary.

Building soil life is different from avoiding harm. In a 40-year-old olive orchard, three years of added carbon – compost, pruning residues and cover crops – markedly improved soil organic matter and nutrients compared with tillage and mineral fertilizer, with favourable signs for soil biology. [7] In southern Italy, 18 years of sustainable management raised topsoil organic matter and the bacteria involved in nitrogen cycling, although overall bacterial diversity did not change. [8] Soil builds slowly, and it responds to what is put back into it.

“Organic-Approved” Doesn’t Mean Harmless

Copper-based fungicides are permitted in organic farming and widely used against olive diseases. Copper binds tightly to soil and accumulates with repeated use. Natural soil levels typically range from 2 to 50 mg/kg, but vineyard soils in France and Brazil have been measured above 1,000 mg/kg after years of copper sprays. [9] In an Australian orchard with copper-contaminated soil, researchers documented effects on earthworms. [10]

As we saw in Part 1, copper also tracked with lower phenolic levels in olive leaves. An approved input is not necessarily a harmless one.

The Diversity Deficit

Many olive groves – organic or not – are monocultures standing on bare earth. Diverse ground cover feeds soil organisms with a wider range of roots and residues. In a long-term study of a high-density olive orchard, protective green cover increased soil respiration and the native mycorrhizal potential of the soil compared with tillage. [11] The fungal partners we met in Part 1 depend on living plants above ground.

The Economics of Transition

Changing course takes investment. Growers who move away from tillage need new equipment and new skills, and may face a period of adjustment.

Fermín Ibáñez Guzmán’s family farm, Nava, is 100 hectares of olives in Jaén, the heart of Spanish olive country. In 2019 he began moving to no-till, cover crops and added organic matter, with no chemical inputs. He reports saving about 2,000 litres of diesel and roughly €10,000 a year on herbicides and fertilizers, along with rising soil organic matter and fewer pest problems. [12] It is one farm’s story, reported by the organization whose programme he joined – but it shows what the transition can look like from the ground.

Beyond Organic: Measuring What Matters

The chain we have followed through this series runs from living soil to a resilient tree, to protective compounds in the fruit, to careful processing that carries them into the bottle. Organic certification addresses part of the first link: what goes onto the land. Regenerative practice goes further, actively rebuilding the soil’s living systems.

But only measurement shows what actually arrived in the bottle. That is why the future of olive oil quality depends not only on how olives are grown, but on verifying the result, harvest by harvest.

In Part 4, we’ll explore how regenerative agriculture is being applied to olive production – working with nature’s intelligence rather than against it.

Aristoleo has championed regenerative practices in the production of high phenolic olive oil for years, and shares that work in Beyond Organic, Beyond Extra Virgin. [13]

Part 1: The Hidden World Beneath Olive Trees
Part 2: How Modern Farming Destroys Soil Biology
Part 4: Regenerative Agriculture – Working with Nature’s Intelligence
Part 5: The Future of Olive Oil

References

  1. Montes-Borrego M, Navas-Cortés JA, Landa BB. (2013). Linking microbial functional diversity of olive rhizosphere soil to management systems in commercial orchards in southern Spain. https://agris.fao.org/search/ar/records/679bacea969e37f4376ff36b
  2. Influence of a shift from conventional to organic olive farming on soil management and erosion risk in southern Spain. Renewable Agriculture and Food Systems (2007). https://resolve.cambridge.org/core/journals/renewable-agriculture-and-food-systems/article/influence-of-a-shift-from-conventional-to-organic-olive-farming-on-soil-management-and-erosion-risk-in-southern-spain/DC947C8C08D14C90A0F8CE5064F9080E
  3. Regulation (EU) 2018/848 on organic production, Annex II, Part I; Council Regulation (EC) No 834/2007, Article 12. https://eur-lex.europa.eu/eli/reg/2018/848/2018-06-14
  4. Soriano MA, Álvarez S, Landa BB, Gómez JA. Soil properties in organic olive orchards following different weed management in a rolling landscape of Andalusia, Spain. Renewable Agriculture and Food Systems (published online 2012). https://resolve.cambridge.org/core/journals/renewable-agriculture-and-food-systems/article/soil-properties-in-organic-olive-orchards-following-different-weed-management-in-a-rolling-landscape-of-andalusia-spain/D4E48B018F53E844E2918BD7F9BCFC38
  5. Gucci R, Caruso G, Bertolla C, et al. (2012). Changes of soil properties and tree performance induced by soil management in a high-density olive orchard. European Journal of Agronomy 41: 18–27.
  6. García-González I, et al. (2019). Mycorrhizal, nutritional and virgin olive oil parameters affected by groundcovers. Journal of Plant Nutrition and Soil Science. https://doi.org/10.1002/jpln.201800439
  7. Bechara E, Papafilippaki A, Doupis G, Sofo A, Koubouris G. (2018). Nutrient dynamics, soil properties and microbiological aspects in an irrigated olive orchard managed with five different management systems involving soil tillage, cover crops and compost. Journal of Water and Climate Change 9(4): 736–747. https://doi.org/10.2166/wcc.2018.082
  8. Sofo A, Ricciuti P, Fausto C, et al. (2019). The metabolic and genetic diversity of soil bacterial communities depends on the soil management system and C/N dynamics: The case of sustainable and conventional olive groves. Applied Soil Ecology 137: 21–28. https://doi.org/10.1016/j.apsoil.2018.12.022
  9. Advances in viticulture via smart phenotyping: current progress and future directions in tackling soil copper accumulation. Frontiers in Plant Science (2024). https://doi.org/10.3389/fpls.2024.1459670
  10. Van Zwieten L, Merrington G, Rust J, Kingston T, et al. Fungicides and Soil Health: Challenges for the Industry. https://www.researchgate.net/publication/228477772
  11. Turrini A, Caruso G, Avio L, et al. (2017). Protective green cover enhances soil respiration and native mycorrhizal potential compared with soil tillage in a high-density olive orchard in a long term study. Applied Soil Ecology 116: 70–78. https://doi.org/10.1016/j.apsoil.2017.04.001
  12. Climate Farmers. How Fermín is transitioning his farm to regenerative agriculture in Spain. https://www.climatefarmers.org/blog/how-fermin-is-transitioning-his-farm-to-regenerative-agriculture-in-spain/
  13. Beyond Organic, Beyond Extra Virgin. https://medium.com/beyond-organic-beyond-extra-virgin