Degradation of allelopathic biomass formulations applied to soil for weed control

Abstract

The objective of progressively replacing synthetic herbicides in the EU in the next decade necessitates the development of new techniques and practices for adoption in Integrated Weed Management (IWM). Consequently, the proposal to apply preparations based on allelopathic biomass as herbicide requires a knowledge base about the processes of release and transport of bioactive substances from the biomass buried in the soil to the target organs of the weeds. Under the same criterion as the controlled-release synthetic formulations, the physical processes that could affect the release of allelopathic compounds after their application to the soil are studied. This work examines the morphological changes of processed eucalyptus plant material (phyllodes and fine branches) through a pot trial and subsequent morphological analysis using X-ray microtomography. The 3D analysis of the tomographies shows that after 20 days of incubation in the soil, there is a notable modification of the biomass structure, an increase in porosity, and an effect on the secretory cavities of the phyllodes. Therefore, the progressive decomposition of the tissues can act as a release mechanism controlled by the environmental conditions of the soil. This control determines the phase transfer of bioactive substances from the allelopathic biomass through the soil pores to the target weeds.