Effects of Volcanic Zeolite Tuff on Olive (Olea Europaea L.) Growth and Soil Chemistry under a Constant Water Level: Five Years’ Monitoring Experience

Abstract

This study investigated the effects of using fine and coarse volcanic zeolite tuff on the growth of olive (Olea europaea L.) trees and the silty clay soil in which they were grown. Olive trees were grown in four different soil treatments: silty clay soil (S1, control), silty clay soil covered with coarse volcanic zeolite tuff (S2), silty clay soil mixed with fine volcanic zeolite tuff (S3), and silty clay soil mixed with fine volcanic zeolite tuff covered with coarse volcanic zeolite tuff (S4). The morphological and physiological characteristics of the olive plants were then monitored over a 5-year period from 2012 to 2016, and the leaf and soil chemistry were analyzed at the end of the monitoring period. It was found that the addition of volcanic zeolite tuff (treatments S2, S3, and S4) had a positive effect on shoot length (relative increases of 10%, 21%, and 29%, respectively), plant height (0.53%, 1.29%, and 3.5%), plant weight (13%, 22%, and 32.26%), number of branches (14%, 27%, and 41.5%), number of leaves (9%, 22%, and 43%), trunk diameter (9%, 22%, and 29%), and shoot diameter (12%, 22%, and 36%), as well as the relative water content (15%, 22%, and 36%) and leaf water potential (16%, 26%, and 32%) compared with the control treatment (S1). Furthermore, the contents of N and P in the plant leaves, and most of the soil chemical parameters measured significantly increased following the addition of volcanic zeolite tuff. These results highlight the benefits of using volcanic zeolite tuff as a natural, readily available, and low-cost material for soil amendment due to its large effects on plant growth and soil fertility.

Keywords

• nutrients
• plant water status
• soil amendment
• volcanic zeolite tuff
• olive tree