Feasibility of Using Orange Wattle (Acacia cyanophylla Lindl.) Compost as an Organic Growing Medium for the Production of Cork Oak (Quercus suber L.) Seedlings

In developing countries, or in those countries that do not produce peat, forest soil has traditionally been used as a substrate for cultivation of seedlings in forest nurseries. However, forest soil as a substrate has not been found to produce seedlings of high quality. Additionally, the harvesting of forest soil within forested stands has negative environmental connotations. The objective of this study was to evaluate the use of Acacia cyanophylla–based compost as an alternative growing media to forest soil for the production of cork oak (Quercus suber L.) seedlings in forest nurseries. The experiment was a Randomized Complete Block (RCB) design consisting of four blocks. Each block consisted of fifteen randomly distributed containers for each of the two treatment substrates (forest soil– and Acacia cyanophylla–based compost). Therefore, in total, 120 acorns were examined. Variables related to seed germination, plant growth, and survival were measured. Germination was high, exceeding 90% in both substrates. However, the compost-based substrate had significantly shorter germination times and an increase in the uniformity of the timing of germination. Seedling growth was significantly affected by the type of substrate, while seedling survival was not. As substrates, compost statistically significantly increased the height (39.2 vs. 33.3 cm), diameter (4.5 vs. 3.5 mm), and total biomass (14.7 vs. 10.4 g) of seedlings relative to forest soil. Based on our findings, the use of compost was found to be an attractive alternative to the use of forest soil in forest nurseries, due not only to the environmental benefits, but also due to improvement in seedling quality.