Regenerative Viticulture Insights: Discussing vine nutrition and soil health with Sergio Nicolau

Regenerative Viticulture Insights: Discussing vine nutrition and soil health with Sergio Nicolau 1050 1313 Sectormentor

Regenerative Viticulture Insights: Discussing vine nutrition and soil health with Sergio Nicolau

We recently shared three amazing discussions from our second edition of the Regenerative Viticulture Series.

To celebrate our learnings, we’re releasing a roundup of each of the sessions and some of our favourite insights from them. In our first instalment we pulled together some highlights from our conversation with the brilliant Mimi Casteel which you can read here. Our next conversation was with Sergio Nicolau, a leading light in the regenerative viticulture world with a deep understanding of plant and soil biology.

Sergio is a 5th generation farmer based in Torres Vedras, Portugal. Sergio’s extensive knowledge is a result of many years of experience as farm manager plus working within his family’s vineyard and winery, coupled with his studies in conventional agronomy. In 2018 Sergio converted the vineyard to organic production after beginning to understand the detrimental effect conventional agricultural practices are having on the health of the environment. He has been studying ways in which to increase the health of his farm’s ecosystem ever since, learning from regenerative agriculture experts such as Gabe Brown and Nicole Masters and implementing these practices on his land. 

One of these practices was to establish cover crops in the alleyways between the vines. Sergio takes diversity to the next level, advancing from his previous mix of 12 species from three plant families to 16 species from 6 different families including: grasses such as ryegrass and black oats; legumes including four different clovers, alfalfa and vetch; mustards, turnips, radishes, beets, spinach; and plants that will encourage pollinators such as buckwheat, calendula and phacelia.

Sergio found that changing the cover crop mix to one that is more diverse has made a big difference to his soil health. Before implementing cover crops the vineyard experienced issues with soil runoff during periods of heavy rainfall. Cover reduces this through slowing down the individual rain droplets, intercepting them before they hit the soil; while the roots act as an anchor, holding soil aggregates in place, reducing erosion and nutrient loss. A diversity in root architecture enhances these benefits as it allows for more layers of soil to be penetrated, improving structure through breaking up compaction layers and opening up pores in the soil allowing water to infiltrate more effectively. 

Sergio also uses his neighbours sheep to graze his covers during winter when the vines are dormant using holistic planned grazing practices. This maintains the growth of his cover crops, while improving soil and vine health by introducing a source of organic matter and nutrients through the sheep manure.

Pictures of soil run off from the neighbouring vineyard without covers crops (left), and Sergio’s vineyard with cover crops established both in-between and under vines rows (right)

Sergio goes on to explain how encouraging a diverse range of plant species will also benefit the biological health of the soil

“It all starts with photosynthesis and the end product which is sugars.” Sugars go to three main points in a plant: the shoot tips, fruit and the excess goes to the roots. Meaning the higher your photosynthetic capacity the more root exudates are released into the soil, feeding the biology within it. Diversity is key here for a few reasons, firstly diverse mixes will grow plants of varying heights with different leaf sizes and shapes that can capture more sunlight at all levels. Secondly, “the more varied your species, the more varied your root exudates – different plants feed different biology and it’s this diversity that is important”. 

Sergio also discussed the effect different plant species have on the redox potential of the soil, creating either disease suppressive or disease enhancing soils. Some plants are more oxidative, such as GMO (modified species), whilst species such as clovers, black oats or mustard are more reductive. He states that it is good to experiment with a diverse range of covers in order to find out which species work in your system: “Now I have learned enough to know that the next mix will be different and maybe I do not have to grow as many species, just the right ones”. 

“Cover crops are a very good tool to start, to give a boost to the system, but then the natives come and it is like a natural succession – often times the natives are better as they are more resilient”

It is amazing to see that despite being in very arid conditions the ground cover in Sergio’s vineyard is extremely healthy, green and lush! A testament to his management.

                              Picture of a diverse, species rich cover crop established in Sergio’s vineyard

We then took a dive into plant nutrition, discussing some amazing findings from experiments within his own vineyard

It is believed that nutrition is a key factor to plant immunity, the more balanced nutrition a plant has the more resilient they become to pests and diseases. It was during an insect attack on his vines that Sergio really saw the power of increased nutrition. Being certified organic meant Sergio was compelled to search for alternative approaches to the use of insecticides. He found that insects have simple digestive tracts and cannot digest complex proteins or amino acids. If you increase the presence of these compounds within a plant insects will stop seeing it as a food source. He found that molybdenum is a cofactor for the enzyme that reduces nitrates and allows nitrogen to form amino acids and complete proteins. After applying a spray of molybdenum, magnesium and sulphur, Sergio found that within two days the insects were no longer feeding on the vines having moved on to the weeds instead!

“Insects are the garbage collectors of nature, they come in and take out of the system plants that are not healthy. So if you have really healthy plants that do not have nitrates or simple sugars and are photosynthesising well, they will not look at the plant as food.”

Sergio now regularly measures the nutritional makeup of his plants using sap analysis in order to decide what nutrients to apply in his vineyard. This is not only useful to get a sense of the vines health and the extra help they may need, but also for understanding what sprays he should cut back on in order to improve nutrition. An excess of some nutrients may have an undesired affect, for example high levels of potassium will block other nutrients such as calcium and magnesium. While other nutrients will have a positive relationship with each other, meaning you may only have to apply one to get an increase in three nutrients. Sergio believes it is very important to understand these synergies in order to be efficient and economic with your applications.

Abby and Sergio discussed that although sap testing is often just a snapshot in time, the idea is that you’re improving the plants health in that moment, in turn increasing it’s photosynthetic capacity and its ability to feed soil biology. This will support the development of a healthy soil ecosystem, promoting long term health and resilience and reducing the need to apply these artificial foliar nutrients in the future.

“It’s like a feedback loop, if the plant grows more healthy, the more biology it will feed, and the more biology you create in the soil the less you need these nutrients.”

Pictures of soil tests performed in Sergio’s vineyard, observing topsoil depth and soil structure

Alongside conventional sprays Sergio is also experimenting with the best way to make and apply nutrients

Sergio has stopped buying commercial products of micronutrients in their oxidised form as he believes the plants will not be able to neutralise them as well. He instead does his own chelation at home using the raw nutrient mixed with a carbon source such as fulvic acid, molasses and seaweed to make nutrient extracts

He also produces additional extracts using more natural ingredients including seaweed, which is high in nutrients and provides beneficial hormones for the plants; plant extracts such as horsetail extract which is rich in silicon and fights fungal disease through drying out the leaves; and shrimp extract which helps boost plant immunity, furthering its resilience against disease. Sergio also discussed his use of fish hydrolysis within the vineyard which provides protein and organic nitrogen to the vines themself, while also supplying a good source of healthy fats which feed the fungal communities within the soil. 

Sergio uses two separate extraction methods to produce fish hydrolysis: when used as a soil fertiliser he will shred the fish waste and mix it with water, molasses and lactic acid; when aiming to create a foliar for the leaves he uses Korean Natural Farming techniques: mixing equal weights of fish waste and brown sugar. 

Abby and Sergio moved on to discuss the importance of building soils that are more fungal dominated in vineyards. Years of using conventional tillage and chemical fertilisers has decreased the fungal communities within Sergio’s soil, leaving it dominated by bacteria. To combat this Sergio uses both fish hydrolysis alongside a compost extract made using the Johnson-Su technique. Johnson-Su composting aims to grow a biologically diverse soil microbiome that is fungal dominated and applied to the soil as a microbial inoculant in the form of a liquid fertiliser. Sergio applies this in his vineyard using a sprayer and mixes in fish hydrolysis, humic acid and micro nutrients to act as food for the biology in his compost extract, “sending out the biology with a lunch box”.

The benefits of the use of these nutrient extracts coupled with the regular monitoring Sergio’s is performing is shown through the brix level of his vines. The first year he started applying nutrition more seriously the brix of his vines measured at 4-6%, and has increased to a brix level of 17-21% measured just before last year’s harvest. Considering the ideal brix level for healthy and resilient vines is 12%, this is truly an incredible result for Sergio!

Pictures of Johnson-Su reactors being built at Sergio’s vineyard – made from shredded wood, sheep dung and waste green matter collected from the vineyard

Finally, Sergio discusses how transitioning to these regenerative practices has affected his vineyards finances. During the three years of organic conversion Sergio did not experience any improvements financially, as while he was spending less on inputs he also experienced a reduction in yield from weaning his vines off of relying on chemical fertilisers, and through his conversion to a vine species that produces less but higher quality fruit. However, now out of his conversion period Sergio is able to sell his grapes at three times the price and is now producing his own wine, adding value to his business. These changes in management practices have decreased his cost of production and increased his economic return.  

It was great to catch up with Sergio and discuss his practical and innovative approach to vineyard management. If you want to learn more about how Sergio implements these regenerative practices in his vineyard, listen to the full conversation in the video below!

All of the beautiful images in this blog were taken from Sergio’s Instagram account – follow him at @sergio.grapegrower for more insights.