Abstract
Aims
Container-grown crops need reliable growing media that provide optimal conditions for plant growth. The traditional media peat and coconut coir are increasingly being replaced with sustainable alternatives. However, the availability of essential nutrients, such as manganese (Mn), in compost-based media remains a concern. This study therefore aimed to investigate Mn deficiencies in tomato seedlings grown in a compost consisting of 30% v/v sewage digestate and 70% v/v garden waste.
Methods
Tomato plants were cultivated from seeds under nursery conditions for eight weeks. The physical and chemical properties of the growing media, including bulk density, total pore space, air content, water retention, pH, electrical conductivity (EC), and essential nutrients, were assessed. Plant growth parameters such as height, leaf number, chlorophyll content, and fresh/dry weight were measured, alongside nutrient analysis.
Results
Despite the high Mn content in the compost, the tomato plants exhibited significant Mn deficiency. Factors contributing to this deficiency included high pH, abundant organic matter, and elevated iron and calcium levels, which likely formed insoluble compounds, reducing Mn availability. Additionally, the compost's low water retention and structural changes limited plant growth.
Conclusions
The findings emphasize the need to consider Mn availability in compost with a sewage-based component. This study highlights the complexities of nutrient availability in sustainable growing media and the importance of optimizing compost composition to support healthy plant growth.