Dutch agriculture and horticulture aim to reduce resources in agriculture by 2030. Residual organic flows from food chains, not suitable for food or feed, can be used as a soil amendment. The SoilAmend project explores safe use of organic side streams as soil amendments to improve crop yield, resilience, and soil health. It will develop a protocol for measurements and a dashboard for assessing safety and effectiveness, enabling informed stakeholder decisions and increase use of side streams.

Reducing resources in horticulture and agriculture is one of the ambitions of the Netherlands towards 2030, and ultimately to become climate neutral in 2050. Residual flows from agriculture and horticulture, but also from the wider food chain, should be recycled as much as possible and in a safe manner. One way of making use of the valuable organic side streams is to use them as a soil amendment. These soil amendments are products that are applied to increase crop quality (e.g. efficiency of nutrient use), resilience (e.g. resistance to abiotic stress) and yield, reduce soil diseases and can improve soil health (Termorshuizen et al., 2006; Kumar et al., 2023). However, the reported effects that these soil amendments have on crop and soil quality, and yield are often unsubstantiated, and robust methodologies to determine and optimize these effects are lacking. This project will develop applicable knowledge on the use of soil amendments and their effects on soil life and functioning, crops, and safety (food and phytosanitary safety) (Figure 1). Thereby increasing the use of side streams as soil amendment in agriculture.

"This project contributes directly to Mission 2E by supporting the closure of nutrient cycles at the company, sector, and production chain level. It focuses on the development and substantiation of soil amendments, products that improve soil and crop quality, resilience, and yield, based on organic side streams. By generating applicable knowledge on their effects on soil and crop health and food safety, and by developing a protocol including a plant-soil bioassay the project enables the safe and effective use of sustainable raw materials, which will meet all preconditions. Which also links to mission 4B (duurzame veredeling en voedselveiligheid, vers en verwerkt) and mission 4F (meervoudige verwaarding vanaf de agrifoodsector naar food en non-food). The creation of a dashboard ensures that results are accessible, allowing stakeholders to make informed decisions and contribute new data. In this way, the project strengthens the role of the agricultural sector as both user and producer of raw materials and contributes to a more circular and sustainable agricultural system in line with the goals of Mission 2E

WP1

1.1 Overview of available side streams, needs for pre-processing and legislation.
1.2 List of the quality and safety parameters of the different side streams.
1.3 Overview of analytical approaches to determine quality and safety parameters. (internal report).
1.4 Insight in the most important parameters and variation in the different side streams.

WP2

2.1 Overview of possible pre-processing options per side stream (internal report).
2.2 Pre-processed side streams produced for experiments in WP3.
2.3 Overview of beneficial mixtures of side streams.
2.4 Overview of the range of fluctuations for relevant side streams.
2.5 Approach to deal with batch-to-batch variation for relevant side streams.
2.6 A workshop in Year 1 to discuss potential added value, practical and logistic requirements to valorizing side streams as soil amendment with all partners; this workshop will also be open to companies and other interested parties outside the project and might result in additional partners joining the consortium.
2.7 A workshop in Year 3 where results of WP1 and T2.1-T2.3 will be discussed and input for the final pilot (T3.4) collected. The outcome of this workshop will be used to prioritize side streams and mixes for T3.4.
2.8 A factsheet with outcomes of the pilot that partners can use after the project helping to facilitate further use of the results and establishing of added value in the chain on the longer term.

WP3

3.1 Definition of criteria for a standardized bioassay system and parameters to measure (with partners and stakeholders) (factsheet/report).
3.2 Results of germination and plant-soil bioassay systems for selection of side streams (factsheet/report).
3.2 Selected germination assay.
3.4 Selected plant-soil assay.
3.5 Validation bioassay results of selected side streams under field conditions.
3.6 Results from execution of the selected bioassays for a wide range of side streams (factsheet/report).
3.7 Overview of results from T3.6 ready to be incorporated in dashboard (T4.3).

WP4

4.1 List of end-user needs and requirements.
4.2 A list of input variables that has been reviewed by all project partners.
4.3 Mock-up dashboard.
4.4 Final unified protocol.
4.5 Dashboard demonstration to project partners.

WP5

5.1 Annual progress and financial reports for the funder.
5.2 Organization of regular project team meetings (twice a year).