Articles
RHP REQUIREMENTS FOR THE SAFE USE OF GREEN WASTE COMPOST IN PROFESSIONAL HORTICULTURE
Article number
891_34
Pages
281 – 286
Language
English
Abstract
For many years in the Netherlands the use of green waste compost was limited to the retail sector.
The main reasons for not using this material for professional horticultural purposes were the risks concerning pathogens, stability and high salt content.
The commercial pressure from countries like the UK to use waste materials like compost also for professional uses made the sector to look at possibilities to use green waste compost as a safe product for growing media production under the RHP quality mark.
Risk assessment showed that, for green waste compost the aspect of the possible occurrence of plant pathogens was the main threat.
To prevent problems in the end product a hygienisation should take place, a limited number of raw materials can be used and the site and logistic system should prevent contaminations.
The hygienisation process for RHP compost from green waste is 14 days at a minimum temperature of 55°C for all parts of the compost pile.
A hygienisation model has been developed to predict the hygienisation degree based on size of the pile and the turnovers.
By limiting the input of raw materials it is also possible to achieve a lower salt content of the end product.
Another important aspect worked on is the testing method concerning stability, the microbial degradation rate of the organic matter under aerobic conditions.
When unstable materials are added to growing media, they may have a negative impact on plant growth due to reduced oxygen content and/or available nitrogen and/or the presence of phytotoxic compounds.
A suitable method was found in the Oxygen Uptake Rate (OUR). Based on experiments limits were set.
Also more general requirements were set for green waste compost.
These are in relation to physical aspects, contaminants, weeds, human pathogens and growth performance.
The main reasons for not using this material for professional horticultural purposes were the risks concerning pathogens, stability and high salt content.
The commercial pressure from countries like the UK to use waste materials like compost also for professional uses made the sector to look at possibilities to use green waste compost as a safe product for growing media production under the RHP quality mark.
Risk assessment showed that, for green waste compost the aspect of the possible occurrence of plant pathogens was the main threat.
To prevent problems in the end product a hygienisation should take place, a limited number of raw materials can be used and the site and logistic system should prevent contaminations.
The hygienisation process for RHP compost from green waste is 14 days at a minimum temperature of 55°C for all parts of the compost pile.
A hygienisation model has been developed to predict the hygienisation degree based on size of the pile and the turnovers.
By limiting the input of raw materials it is also possible to achieve a lower salt content of the end product.
Another important aspect worked on is the testing method concerning stability, the microbial degradation rate of the organic matter under aerobic conditions.
When unstable materials are added to growing media, they may have a negative impact on plant growth due to reduced oxygen content and/or available nitrogen and/or the presence of phytotoxic compounds.
A suitable method was found in the Oxygen Uptake Rate (OUR). Based on experiments limits were set.
Also more general requirements were set for green waste compost.
These are in relation to physical aspects, contaminants, weeds, human pathogens and growth performance.
Authors
G. Wever, R. Scholman
Keywords
compost, composting, hygienisation, requirements, stability
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