Agronomist Restores 400-Year-Old Olive Grove to Better Withstand Droughts in Croatia

The Zadar County Olive Growers Association con­tin­ues to edu­cate its mem­bers and other inter­ested olive grow­ers.

After a short sum­mer break, the group orga­nized a work­shop on the island of Ugljan in the 400-year-old olive grove of the Marcelić fam­ily.

“This is a typ­i­cal exten­sive olive grove with autochtho­nous vari­eties: Oblica and Drobnica pre­dom­i­nate,” said 29-year-old Šime Marcelić, a doc­tor of agron­omy and owner of the fam­ily grove.

The young sci­en­tist and lover of olive grow­ing said his ances­tors worked for the landown­ers, sav­ing to even­tu­ally buy back the land they cul­ti­vated after the sec­ond agrar­ian reform.

Ugljan is one of the many Croatian islands in the mid­dle of the Adriatic Sea in Dalmatia, where olives have been cul­ti­vated for time immemo­r­ial. Maslinik is located on the south­ern side of the island, 100 meters above the sea.

“As you can see, there are stones and poor soil. The con­di­tions are lim­ited, so it is very dif­fi­cult to work,” Marcelić said.

Drought is a peren­nial prob­lem, which is why the olive grove was aban­doned and rebuilt sev­eral times. Eventually, Marcelić’s late father, Ignacije, began to restore the trees sys­tem­at­i­cally after the Croatian War of Independence, which ended in 1995.

Marcelić con­tin­ues the work of his father. Saplings grew from the cen­turies-old root and devel­oped into trees that reg­u­larly bear fruit despite the impacts of cli­mate change and other unfa­vor­able con­di­tions.

Marcelić attrib­uted the suc­cess­ful revival of the trees to appro­pri­ate agrotech­ni­cal mea­sures, start­ing with prun­ing, fer­til­iza­tion and pro­tec­tion against dis­eases and pests, which he reg­u­larly imple­ments.

Unlike most olive grow­ers, Marcelić prunes the trees four times a year. The first is in January when the olive tree is in win­ter dor­mancy. Thick branches are removed with a saw.

The sec­ond prun­ing is in March. The olive-bear­ing branches are thinned to ensure opti­mal yield in the cur­rent crop and qual­ity growth for the next crop.

The third prun­ing comes dur­ing the sum­mer. Weeds that grow out of the stump are removed. The fourth is dur­ing the har­vest when the ringed branches are removed.

On the island, where the soil is shal­low and skele­tal, empha­sis should be placed on autumn fer­til­iza­tion, Marcelić noted. In con­trast to the con­di­tions on the coast, where the soils are deep and have a good capac­ity for water and where the occur­rence of late spring frosts is fre­quent and expected, spring fer­til­iza­tion should be empha­sized.

In his olive grove, Marcelić applies fer­til­izer between the first sum­mer and the next heavy rain, mostly at the begin­ning of September. He uses mainly organic pel­leted fer­til­iz­ers in com­bi­na­tion with min­eral fer­til­iz­ers that have more phos­pho­rus and potas­sium with the addi­tion of microele­ments.

Marcelić also warned about the dan­ger of infec­tion with pea­cock’s eye, which is the most urgent part of work in olive groves, both on the islands and the coast.

During the autumn, after the first rains, tem­per­a­tures are rel­a­tively high. Wet leaves pro­vide the opti­mal con­di­tion for the devel­op­ment of fun­gal dis­eases, espe­cially pri­mary infec­tions with pea­cock eye.

For this rea­son, Marcelić rec­om­mends that pro­tec­tion is car­ried out before har­vest­ing, espe­cially on sus­cep­ti­ble vari­eties such as Oblica.

Applying pro­tec­tion after the har­vest, which many olive grow­ers do, is too late because fun­gal dis­eases have already infected the leaf. In the spring, the leaf will fall, and noth­ing more can be done.

The olive tree will not have enough leaf sur­face to develop the fruit. Instead, the tree expends its energy renew­ing the leaf mass result­ing in less fruition.

Marcelić also explained how he over­came the drought by restor­ing old olive trees.

“The restora­tion of cen­turies-old trees is actu­ally the first line of coex­is­tence with the drought,” he said. “[It is] the mea­sure by which we reduce the dam­age of the neg­a­tive effects of the drought.”

A young tree with an exten­sive root sys­tem bet­ter tol­er­ates the lack of mois­ture. Marcelić also sprays his reju­ve­nated trees dur­ing the sum­mer.

He applies foliar feed­ing over the leaves. Little by lit­tle, he fills and lev­els the ter­rain, crushes the stone with heavy machin­ery and thus prac­ti­cally imple­ments karst melio­ra­tion.

The rain that fell last week­end was rather late, but it will help the fruits to con­tinue devel­op­ing. The final result depends on the tem­per­a­tures.

“Oil accu­mu­lates from 23 ºC upwards,” Marcelić said. ​“The final amount of oil will depend on that and the amount of rain before the actual har­vest.”

He expects his 100 restored olive trees to bear 1,000 kilo­grams of fruit and about 200 liters of oil.

Marcelić, who also works at the University of Zadar’s agri­cul­tural depart­ment, spends his free time help­ing other olive grow­ers graft and main­tain their trees.

Ivica Vlatković, the pres­i­dent of the Zadar County Olive Growers Association, laments that there are not more young farm­ers like Marcelić to restore neglected olive groves.

He con­tends that if more young peo­ple planted olive trees, the num­ber in Croatia could rise from the cur­rent five or six mil­lion to the 30 mil­lion that flour­ished in the coun­try dur­ing the 18^th cen­tury.