Using Effective Microbes to Boost Organic Olive Yields in New Zealand

Long con­sid­ered the domain of pseu­do­science, one award-win­ning olive oil pro­ducer in New Zealand is bet­ting on increas­ing the effec­tive microbes in his soil.

Ross Vintiner, the co-owner of The Vintiner’s Grove, told Olive Oil Times that since he started using effec­tive micro­bial mixes in his olive grove, he has cut down costs on fer­til­iz­ers, improved soil health and expe­ri­enced higher olive oil yields.

“At Dali Estate (where the Vintiner’s Grove’s olives are grown), we use micro­bial brews, com­post teas, com­post extracts – and prac­tice organic and bio­dy­namic farm­ing – to grow diverse liv­ing soil and world-class olives,” he said.

“In doing so, we have main­tained our pro­duc­tion, cut our exter­nal nutri­ent inputs and pro­duc­tion costs, thereby improv­ing the triple bot­tom line for us and the planet,” Vintiner added.

“Effective microbes enhance plant growth and pro­duc­tiv­ity by fix­ing atmos­pheric nitro­gen and sup­ple­ment­ing the plants with the fixed nitro­gen as ammo­nia,” a team of researchers from the Kalinga Institute of Industrial Technology University in India wrote in a 2020 study pub­lished in the jour­nal Sustainable Environment Research.

“Additionally, the release of trace ele­ments, secreted antiox­i­dants, exopolysac­cha­rides, bioac­tive com­pounds (vit­a­mins, hor­mones and enzymes) by the effec­tive microbes stim­u­late plant growth and pro­duc­tiv­ity,” they added.

Vintiner said effec­tive microbes also sequester car­bon and improve nutri­ent reten­tion in soils.

“Effective microor­gan­isms are pro­bi­otics, stim­u­lants and enhancers for soil, plant and waste treat­ments,” he said. ​“They are one class of micro­bial mixes and can be used with nutri­ents to pro­mote soil and plant biol­ogy for per­for­mance and pro­duc­tion.”

Vintiner added that diverse trees and a mixed sward feed graz­ing ani­mals above the soil help pro­duce ​“highly desir­able fun­gal and improved soil for our main cash crop, olives.”

“Microbial mixes cost a frac­tion of exter­nal nutri­ent inputs,” Vintiner said. ​“For exam­ple, we use olive pomace from the press in an anaer­o­bic brew which tests high in nitro­gen, potas­sium and sul­fur, three impor­tant nutri­ents for olive pro­duc­tion.”

“The mix has medium amounts of ben­e­fi­cial microbes and is applied as a soil drench, boosted with our own fun­gal com­post extract, for around $10 New Zealand (€5.50) per hectare,” he said.

Along with their low cost rel­a­tive to syn­thetic fer­til­iz­ers and pes­ti­cides, Vintiner said using effec­tive microbes helps reduce the global phe­nom­e­non of soil loss.

According to the United Nations Food and Agriculture Organization (FAO), 75 bil­lion tons of soil are lost from arable farm­land yearly, cost­ing an esti­mated $400 bil­lion (€375 bil­lion) in agri­cul­tural pro­duc­tion loss.

“Dali Estate had such ori­gins. Its soil life was poor and sick,” Vintiner said. ​“This is com­mon in many olive groves I con­sult on. Microbes and their envi­ron­ment are on life sup­port. They are lit­tle under­stood by many farm­ers.”

“We are destruc­tive to these indis­pens­able, ancient and valu­able life­forms,” he added. ​“We pol­lute and destroy microbes with expen­sive chem­i­cals and soil man­age­ment, see­ing lit­tle increased pro­duc­tion or finan­cial ben­e­fit as a result… Microbes are the future of farm­ing.”

Among the effec­tive microbes adopted by Vintiner in his olive groves is myc­or­rhizal fungi.

According to the Kalinga Institute of Industrial Technology University researchers, the fungi take car­bo­hy­drates from plant roots and, in turn, increase the sur­face area for water, nitro­gen, phos­pho­rous and inor­ganic nutri­ents to be absorbed by the plant.

“For olive grow­ers, plant­ing with myc­or­rhizal fungi rapidly increases growth with­out using fer­til­iz­ers. This can also be done ret­ro­spec­tively with estab­lished olive trees,” Vintiner said.

“At a new olive grove, a myc­or­rhizal fungi sachet was inserted into each plant­ing hole with an olive tree,” he added. ​“Three years on, soil with vir­tu­ally no life is now liv­ing and grow­ing olive trees dou­ble the size of their con­trol con­tem­po­raries in other non-inoc­u­lated groves. You can also ret­ro­spec­tively inoc­u­late olive trees with myc­or­rhizal fungi, as I have done, with supe­rior growth achieved in inoc­u­lated trees.”

Vintiner cred­ited the use of effec­tive micro­bial mixes for improv­ing Dali Estate’s oil yield, which he said is above aver­age accord­ing to Olives New Zealand data.

“This has been achieved with reduced exter­nal inputs,” he said. ​“For exam­ple, nitro­gen, the growth nutri­ent, is applied as fish hydrolysate (ground-up fish trans­formed into a liq­uid phase) to feed the microbes. We no longer apply phos­pho­rus or potas­sium.”

“At scale, com­post is not an option, so we rely on foliar and ground micro­bial mixes, along with deficit organic inputs, to main­tain pro­duc­tion and yield and increase plant resilience,” Vintiner added. ​“This is impor­tant as oil yield is a mul­ti­di­men­sional out­come, weather being a major ingre­di­ent.”

Away from the oil yield, Vintiner listed var­i­ous soil health met­rics that have improved since he began reg­u­larly apply­ing effec­tive micro­bial mixes.

“Since using micro­bial mixes, sward diver­sity has increased, and with it, rhi­zosheath, the soil-crumb-encas­ing roots [that facil­i­tate the uptake of nutri­ents], has improved dra­mat­i­cally,” he said.

Dali Estate has found their worm count has increased from five to 25 worms per spade in that period. Their organic mat­ter and total soil car­bon have dou­bled in the past five years, and annual soil tests con­firm nutri­ent loss is min­i­mal.

“Regular plant tis­sue tests, Brix mon­i­tor­ing and dis­ease pres­sure also show pos­i­tive out­comes,” Vintiner said. ​“On the crit­i­cal mea­sure of soil micro­bial bio­mass, Dali Estate has gone from being bac­te­ria dom­i­nant three years ago to three-to-one fun­gal dom­i­nant. Trees thrive in soils teem­ing with fungi.”

“All these indi­ca­tors, includ­ing improved drainage and sta­ble soil test results, indi­cate ben­e­fits of reg­u­larly and strate­gi­cally apply­ing micro­bial mixes,” he added. ​“Furthermore, it reduces the impact of droughts, the envi­ron­ment and cli­mate change.”

While an emerg­ing num­ber of com­pa­nies focused on effec­tive micro­bial mixes are spring­ing up in New Zealand and else­where, Vintiner has his own recipe.

He said this mix­ture can be used imme­di­ately or stirred and bub­bled for 24 hours. After that, it can either be used or stored for up to four days with the drum cov­ered loosely.

“This is an inex­pen­sive micro­bial mix and seed inoc­u­lant made from fun­gal com­post, applied as a ground drench six times dur­ing the grow­ing sea­son,” Vintiner said. ​“It has a high micro­bial bio­mass. The mix is best used within 24 hours but will last up to four days.”

He added that it can be applied with nutri­ents, bio­dy­namic prepa­ra­tions or a car­bon source such as humic acid. Alternatively, it can be used on its own, diluted in water.

For 100 liters of the micro­bial mix, place three kilo­grams of fun­gal-dom­i­nant com­post in each of two thor­oughly cleaned 20-liter-size buck­ets and fill both with one-third water.

Stir vig­or­ously with a paint mixer for around 60 sec­onds, then sieve into 80 liters of warm rain­wa­ter – the warmer, the bet­ter – in a thor­oughly cleaned 100-liter-size drum. Using a hose, spray the remain­der of the com­post in the sieve, extract microbes and nearly fill the 100-liter tank. Add one liter of kelp and another liter of fish hydrolysate to the drum.

Vintiner makes com­post from ramial branches, the side-fruit­ing branches, from Dali’s Italian alder trees, which are chipped and hot com­posted in autumn for up to 12 months.

“The result is a crumbly, soil-like fun­gal com­post with very high micro­bial bio­mass,” he said. ​“This com­post is a cen­tral ingre­di­ent in all our micro­bial mixes.”

Additional ingre­di­ents that can be added are Azospirillum (nitro­gen-fix­ing rhi­zobac­te­ria for the root zone), two table­spoons of biochar dust or two table­spoons of basalt dust. Next, the micro­bial bio­mass is tested.

When applied, half-fill­ing a clean spray tank, cir­cu­late the mix­ture, adding nutri­ents and humic acid if desired. The micro­bial mix is then added to the spray tank.

Vintiner pre­pares at least 25 liters of the mix­ture (applied with water) per hectare. He rec­om­mended spray pres­sure of no higher than 60 pounds per square inch to pro­tect the microbes before or after rain in the morn­ing or evening.

“Using reduced organic nutri­ent inputs, always with microbe appli­ca­tions, means lit­tle to no nutri­ent loss and run-off to our wet­land or the envi­ron­ment,” Vintiner said. ​“Microbes help retain and sup­ply nutri­ents.”

“Reduced inputs and a bet­ter-func­tion­ing, micro­bial-rich soil reduces pol­lu­tion and nutri­ent loss,” he con­cluded. ​“Using a range of tools, includ­ing biochar and fun­gal com­post, we sequester car­bon diox­ide into our soil for the ben­e­fit of microbes, plants, food, humans, the bios­phere and the planet.”

• U.N. Food and Agriculture Organization
• PeerJ