A nature-based innovation for weed control is being developed at the LSIWC

For years, synthetic herbicides and plastic mulch have promised yields, yet at the cost of degrading soil health, biodiversity, and public trust in food safety. Moreover, weeds are responsible for 30–40% yield loss in crops and facilitate the spread of pests and diseases (Kostina-Bednarz et al., 2023). While synthetic weed control products are still widely used, there is growing demand for sustainable, environmentally friendly alternatives that prevent herbicide resistance and safeguard healthy soils for future generations.

Researchers at LSIWC are asking a different question: has nature already provided more effective solutions? The team is currently developing a novel sprayable mulch enriched with walnut-derived bioherbicides — an alternative that brings together science, ecology, and circular economy principles.

This innovation builds on the long-known self-regulating capacities of plants. By valorizing walnut (Juglans regia) processing by-products, researchers extract allelochemical compounds such as juglone (5-hydroxy-1,4-naphthoquinone) — a natural herbicide known to inhibit cell division, reduce root growth, and interfere with plant metabolism (Kostina-Bednarz et al., 2023; Khamare et al., 2022). 

The Innovative Solution

Walnut trees are known for their ability to inhibit the growth of neighboring plants due to the chemical composition of walnut biomass. In this project "Developing a biodegradable sprayable mulch", bioherbicides such as juglone will be extracted from walnut cultivation and processing waste. These bioherbicides will then be immobilized in a biopolymer matrix to prevent their dispersion in the soil and ensure selective action against weeds without harming crops. The resulting starch-based compositions will form a protective film on the soil's surface after spraying and drying. The combination of mechanical and chemical action will enhance weed control efficiency. After use, this mulching film can be integrated into the soil, and its components, including bioherbicides, will break down over time into harmless compounds that do not accumulate in the environment.

This approach directly addresses one of modern agriculture’s most urgent challenges: how to control weeds effectively without damaging soil ecosystems or compromising long-term productivity. It also aligns with the EU’s (Farm to Fork) strategy, which aims to phase out microplastics and hazardous chemicals from agriculture. 

Ready for European Fields

To become a viable alternative to conventional synthetic mulch, the sprayable mulch must meet strict regulatory requirements. According to European standard EN 17033:2018, biodegradable agricultural mulch films must achieve at least 90% biodegradation in soil within 24 months (not just in compost), and must be proven safe for soil organisms including microorganisms and earthworms (EC, CSN En 17033, 2018). Furthermore, the newly adopted EU 2024/2787 allows such biodegradable products to be classified within the EU fertilising product framework and receive CE marking. This means the mulch must pass both lab and field tests to demonstrate safety and efficacy before it can be marketed as a reliable and environmentally friendly product.

To make this journey from idea to implementation, close cooperation between research and industry is essential.

From Garden to Laboratory: Industry Collaboration

Innovation does not happen in isolation — it thrives on collaboration. In this project, LSIWC partners with SIA WESTLAKE, a local walnut grower and processor, which supplies walnut by-products such as shells, husks, and other agricultural residues. This partnership enables the efficient valorisation of agri-industrial waste, creates new market potential for such side-streams, and adds value to walnut biomass.

The project is led by the Latvian State Institute of Wood Chemistry as the main partner.
The project coordinator is Dr. chem. Māris Lauberts (LSIWC), and the scientific supervisor is Dr. chem. Jevgenija Ponomarenko.

Project (ID 24-00-C0LA1601-000012) description: Developing a biodegradable sprayable mulch incorporating walnut husk extracts enriched in allelochemicals for sustainable weed control in agriculture