Biochar and vermicompost use as peat based growing media partial replacement to produce containerized ornamentals

Abstract

The use of organic materials as compost, vermicompost, and biochar as peat substitutes in the ornamental containerized bedding plant production is an interesting biotic strategy to store carbon in garden soil. In the case of biochar the stored C could be maintained for centuries improving the life cycle analysis of this process. Severa! studies have produced interesting results, but additional research is needed to evaluate those materials and how to combine them as compost-biochar or vermicompost-biochar which may produce similar or better plants while also similarly or better support the transplanting process. This research aims to contrast the hypothesis that is possible to grow commercial quality plants of Petunia. hybrida and Pelargonium peltatum using biochar as partía! substitute of peat based growing media. Those plants also will be able to adapt themselves conveniently to a garden soil after being transplanted. Finally will contrast the hypothesis that is possible to diminish nutrients leachate when growing both species using biochar and vermicompost as peat based substrate partial substitute. To contrast these hypothesis three different comparative greenhouse studies were conducted to assess the suitability of biochar and vermicompost as partial substitutes for peat-based growing media for ornamental plant production The three trials mentioned above were therefore defined. After finishing the first experiment it has been possible to affirm categorically that it is possible to cultivate bedding ornamental plants such as petunia and geranium in container with good commercial quality using different mixtures of biochar / vermicompost with a substrate based on peat. The calculation made about potential storage in soil, suggests that it would be possible for long periods of time to store first in the plant 's container and then in urban garden 's soil after transplanting, up to 88.74 g of CO,e per 800 cm3 container. The second experiment has demonstrated that Petunia and Pelargonium plants, grown with the best biochar / vermicompost substrate mixtures of the first experiment, showed a similar or better physiological response than the plants grown on a substrate based on a commercial peat that was used as control. In the third experiment it has been seen that by using these better mixtures, it is possible to reduce both the volume of leachate from the irrigation and the amount of nitrates contained therein, by including biochar / vermicompost in the mixture with the control substrate. It was also verified that the incorporation of biochar to the substrate can suppose an extra source of potassium fertilization that can be considered when planning the fertilization of the crop. These results obtained with different mixtures of biochar and vermicompost may be of interest to those producers of bedding ornamental plants in container who wish to: • reduce the consumption of peat for the production of ornamental plants in containers. • reduce the carbon footprint , and incorporate the owners of gardens where bedding plants can grow to the global biotic strategy of carbon sequestration in soil for long periods of time to compensating in this way the emission of greenhouse gases into the atmosphere and thus contribute to the mitigation of climate change. • reduce nitrate 's leachate of in this productive sector. In this context it has to be indicatively noted, that if we consider that around 11 million metric tons of peat in horticulture are consumed every year in the world. If it is also considered that 50 o/o of this amount was used in floriculture and 20 o/o in container production, then it would be possible to store carbon in urban gardening soil for long periods of time for a maximum value of one million metric tons per year, just by partially replacing the neat of the usual substrate with a mixture of 20 o/o vermicomoost and 12 o/o biochar.