Written by Albert Kravos, InnoRenew CoE

Located in the Istrian region of Slovenia is nestled a farm enveloped in nature, here an olive orchard dwells in a land treated with respect and the faith that organic practices can and will return agriculture to a more sustainable, healthy, and productive way of living, working and thinking about our relationship with the environment that surrounds and nourishes us. Gramona Farm represents what many local farmers strive for and thus is an ideal case for our OLEAF4VALUE project so that the variance in our data is most significant and representative of all the olive cultivation practices. The OLEAF4VALUE project endeavor is challenging as it attempts to mathematically model and predict the variance of chemicals present in olive leaves, thus, alongside the industrially produced olive leaves, this polar opposite of the intensive farming practices is providing us with a precious source of information.

Gramona Farm like other olive growers throughout the European Union are looking for ways to utilize as many parts of the olive tree as possible. Olive leaves are an underutilized part of olive production but contain high-value chemical compounds such as oleuropein.

Gramona Farm is an ecologically oriented farm that strives to reduce to a minimum the amount of synthetic chemicals used for pest and weed control, and nutrients and water management.

Their approach is simply to keep the plants as healthy as possible so that the natural defensive systems of the plant would be enough to keep them healthy, strong, and productive. The value of using waste as a resource at Gramona Farm is complementary to the objectives of the OLEAF4VALUE project.

This year has been extremely dry, already during winter precipitation was below average and even got worse throughout spring and summer.

Now we are in the second week of September and recently, we had some precipitation, however, the deeper layers of soil are still too dry. These extreme conditions affected the production of olives to the extent that many plants show between one-third to one-half of fruit production in a regular year. The only positive thing that this arid summer brought is a conspicuous reduction in the number of olive flies that damage the fruits. The reduced presence of the olive fly allowed the farmers at Gramona Farm to use only ½ L/hectare of GF120 during this summer. On average in our Istrian region, the olive fly pest has a 35-day reproductive cycle; during wet summers like it was in 2014, it has been observed that the reproductive cycle sped up to 28 days increasing the number of flies and the damage to the olives. This year’s average olive fly lifecycle was slowed down to 55-60 days and the inspected fruits show very little damage. It has rained recently, thus the next wave of olive flies is expected to hatch; however, this rainfall came so late that it is expected that the harvest will happen before the olive fly has the chance to damage the crops.

This year at Gramona Farm the microelements delivered via foliar application were iron and magnesium during the first session; boron and molybdenum in the second session; zinc was used in the third application and lastly, an application of algal and plant extracts full of amino acids was also sprayed onto the canopy to reduce the stress experienced by the trees.

The trees were fertilized in spring with a mix of natural compost, grass, wood chips, and 10 % manure at an approximate 50% moisture content. The composting was monitored and mixed to promote sterilization. Before the application of the compost, pellets of stallatico were used to increase the biodiversity of the soil. This type of fertilization and foliar applications are slowly being shifted more and more towards ecological approaches. In September, Cuprablau and microelements were used.

All these procedures are aimed at increasing the photosynthetic capabilities of the plants to boost sugar production, which in turn is used to produce more nutrients and metabolites that maintain the plants healthy and prepared to respond to pest attacks and diseases. It has also been noticed that plants that are in their prime health present a strong “immune system” that makes them much more indigestible to several pests (like the olive fly, but not as much for the brown marmorated stink bug). Symbiotic bacteria and fungi are able to integrate their structure with the structure of the roots to penetrate deep into the root system and greatly enhance the transport of nutrients and water between the parties.

Other techniques to preserve biodiversity are the year-round soil cover, which entails the preservation of the weeds that in turn foster the proliferation of microorganisms, and various insects and make it possible to increase the carbon content of the soil, the air circulation and also water retention, and can lower the temperature at the soil surface which in turn reduces water distress in case of drought.

“Zelena rez” which can be translated as “green pruning” is the act of eliminating some of the branches that started to grow after the flowering period, which means that those branches are also fruitless and thus can be removed.

The waste produced during the “zelena rez” pruning has a great potential to deliver high-quality olive leaves for further biorefining, as they are supposed to be full of polyphenols, triterpenoids and other metabolites and nutrients.