The Evaluation of Olive Pruning Waste As a Vermicompost Feedstock.

Olive prunings are an abundant resource in Turkey but they are often burned by Turkish farmers. Our objective was to evaluate olive prunings as a feedstock for vermicompost. To this end we conducted a laboratory experiment preparing compost from local olive prunings (B) and cow manure (G) with the addition of Eisenia fetida earthworms (S) and without earthworms. The feedstocks were tested individually and mixed with and without earthworms to give six treatments (B, BS, G, GS, BG, BGS). All treatments were incubated in triplicate for 6 months in the laboratory. During the experiment, deionized water was added to all experimental containers to replace evaporative losses and maintain optimal moisture conditions. Available N, P, K, and C/N analyses were carried out on samples from each treatment after 30, 60, 90 and 180 days of incubation. Results were analyzed with repeated measures ANOVA followed by LSD means separation test when warranted. ANOVA indicated a significant interaction between treatment and time.

Earthworm abundance was greatest in the BS application at the end of the incubation, with the number of earthworms increasing about 15-fold during the experiment.

Final C/N ratios of the treatments with earthworms (BS) were lower (14.90) than without earthworms (B, 16.37). The average total Kjeldahl N in all treatments was sufficient as a fertility amendment. They ranged from 1.58 to 2.20% for BGS and BG respectively. Available P was poor in the GS, BS, and BGS treatments. Available K was adequate.

When the incubation treatment*time interaction was taken into consideration, the common effect of time and treatment on N, C/N and K amounts, but not P (p=<0.01) were statistically significant. In the light of these findings, all values obtained from B, BG, BGS, BS, G and GS applications were different depending on incubation time. Olive prunings can be successfully used as a vermicompost feedstock and should not be burned.