Posidonia oceanica (L.) based compost as substrate for potted basil production

Area of Science:

• Horticulture
• Environmental Science
• Soil Science

Background:

• Peat, a non-renewable resource, dominates growing media, prompting European policy to favor alternatives like compost.
• Mediterranean seagrass, Posidonia, yields compostable onshore deposits, offering a sustainable alternative.
• This study evaluates commercial green compost and Posidonia residue compost for peat substitution.

Purpose of the Study:

• To assess the efficacy of green compost and Posidonia residue compost as peat substitutes or complements in growing media.
• To compare the plant growth and nutrient uptake in peat-based versus compost-based growing media.
• To evaluate the potential for reducing heavy metal absorption using compost-based substrates.

Main Methods:

• Comparative analysis of plant growth and nutrient content in various growing media formulations.
• Testing commercial green compost and Posidonia residue compost against traditional peat-based media.
• Quantification of macro and micro-element concentrations and heavy metal uptake (Cd, Cr) in plants.

Main Results:

• All compost inclusion levels significantly increased macro and micro-element concentrations in growing media.
• Peat-based media resulted in higher P, Ca, K, Na, Cu, Mn, Zn, and Fe content and slightly greater biomass than compost-based media.
• Plants in compost-based substrates exhibited lower cadmium (Cd) and chromium (Cr) uptake compared to those in peat.

Conclusions:

• Both green and Posidonia composts can effectively complement peat in growing media, particularly at a 30% inclusion rate.
• Posidonia-based compost demonstrated superior productive performance over green compost.
• Basil grown in compost-based media showed reduced absorption of potentially toxic metals compared to peat-grown basil.