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Summary A shift in food intake towards more plant-based options such as vegetables is emphasised for lowering the environmental impact of food consumption, and organic farming is promoted as a tool to meet European policy goals related to sustainability, environment and biodiversity. However, the current environmental impact of organic vegetable production is not well explored. Here we address the knowledge gap of environmental impacts from organic vegetable production in a life cycle perspective, locate primary impact sources and investigate potential mitigation option scenarios. The assessment focussed on pointed cabbage, cos lettuce and yellow onion in a mixed crop rotation, as common under commercial Danish conditions, and include estimation of soil carbon (C) and nitrogen (N) pools. The system boundary was set from cradle to farm gate, and included inputs to cultivation, soil C and N dynamics in the crop rotation, post-harvest cooling, packaging and storage. The data for modelling was collected from growers, consultants and the scientific literature. We report estimated global warming potential, marine eutrophication potential, land use, water consumption, mineral and fossil resource scarcity and cumulative energy demand from production. The analysis shows that environmental impacts stemmed from several activities dependent on the crop-specific characteristics of production. For summer-grown pointed cabbage, nitrous oxide emissions from high amounts of fertiliser and crop residue was responsible for 40 % of climate impacts, for cos lettuce the production of seedlings with peat as a substrate was responsible for 40 %, of climate impact, and for transplanted yellow onion the post-harvest drying and storage was responsible for 27 % of climate impacts. The identified major mitigation options were an increase in harvest shares of hand-harvested vegetable crops, lower post-harvest loss from onion storage, optimised residue management and substitution of peat as subst

Documentation of stakeholder event - showing the Comcrop pot trial to special invites 24. April 2023 AU FOOD

There is an urgent need to reverse the loss of soil organic matter (SOM) and increase soil productivity fertility to achieve climate goals and sustainable intensification of food production. Compost application is one of the main tools to improve soil functions and provide essential ecosystem services, including C sequestration and sustainable food production. Despite its benefit, compost production and application is facing several challenges, including its intensive labor and skill requirement, slow release of nutrients, and contribution to GHG emissions. Technological advancement has recently been made to reduce the environmental impacts of composting and to further upcycle biowaste to liquid N fertilizer and compost in an automated closed system in 7-9 days. The current study aims to evaluate the quality and agronomic value of the compost produced in the automated system in 7 days at thermophilic temperature (AuDC) in comparison to the conventional windrow method (WrC) and commercial organic fertilizer (OrF). The maturity was tested using the Solvita stability test and phytotoxicity test. The impact of the compost on the soil was evaluated by conducting a controlled incubation experiment for 91 days, during which mineral nitrogen (N) dynamics and enzyme activities were determined in unamended control (CTR) and soil samples amended with 20 Mg DM ha -1 of AuDC and WrC; and 6 Mg DM ha-1 of OrF.

Talk at the Aarhus Festuge in DOMEN: Challenges and solutions in plant-based food primary production in Denmark to achieve a more climate friendly agriculture based on production of vegetables, fruits and legumes

Vegetable crop residues (VCR) can pose environmental impacts in the form of leaching and nitrous oxide emissions, due to their high water contents, N concentrations but low C/N ratios, regardless of utilisation methods. It is vital to investigate its environmental impacts for future sustainable production systems. Carbon and nitrogen (N) concentrations and amount of biomass of VCR are essential parameters used for estimating environmental impacts of VCR utilisations. However, a dataset for those parameters is currently unavailable. In this review, we discuss challenges in accurately estimating VCR N and highlight factors to improve accuracy of estimation and to minimise misunderstandings. We compile the available data of these parameters for Different VCRs. N concentrations/contents, C/N ratios, other nutrient contents (P, K, S, and Mg) of VCR, and harvest index (HI) and nitrogen harvest index (NHI) of vegetables are overviewed for 72 crops across 27 countries with large variations in observation numbers based on published and unpublished data from open field and greenhouse productions. Indirect estimations on VCR are suggested as substitutes for direct measurements when techniques and resources are limited in practices and research. Nitrogen contents of VCRs can be calculated by using HI and NHI. Aboveground/belowground ratios of C and N concentrations as well as biomass of specific crops can be simulated by mechanistic models but require validations. Nitrogen contribution from VCR to cropping systems can be indirectly evaluated by soil mineral N concentrations. Above all, thorough investigations on VCR regarding aboveground/belowground ratios, nutrient concentrations (N, P, K, etc), C/N ratios and HI are needed for more accurate and comprehensive estimations on VCR. Additional research should be conducted to comprehensively investigate environmental impacts and consequences of different VCR utilisation options (handling, harvest, transportation, etc) and innovativ

Investigating the combined effect of plant-based fertilisers and compost on the plant-soil system in a pot trial

In einem Dänischen Gemüsefeldversuch wurde ein nachhaltig-intensives Anbausystem untersucht, in dem reduzierte Bodenbearbeitung, Fruchtfolge, Zwischenfruchtanbau und pflanzenbasierte Düngung kombiniert wurden. Die Bodenqualität wurde im Vergleich zum betriebsüblichen Anbausystem verbessert.

P250 Strip cropping, a type of intercropping, increases the diversity of crop species in the field. Crop diversification in the agroecosystem can potentially increase biodiversity of arthropods, and microorganisms above- and belowground, improve crop yields, and reduce pest and pathogen attacks. We here present a project that investigates the potential benefits of strip cropping under Danish conditions, by 1) design and implementation of optimal strip cropping fields, 2) functional and biological diversity of arthropods, with focus on pests and predators, 3) microbial diversity and pathogen damage, 4) agronomical aspects, such as crop rotation, tillage, weed control, and yield effects, and 5) development of practical implementation, and sustainability analyses. The strip crop fields were established in 2021, in rows with two levels of crop diversity: 3 m rows with wheat, sugar beet, barley, faba bean, rye, oat, pea, and quinoa, and 6 m rows with wheat, sugar beet, barley, and faba bean, in a block design of four repetitions. The arthropod assessments, with focus on arthropod diversity and aphid infestations in faba bean and barley, were conducted by visual observations and the use of trap methods (pitfall traps and pantraps). Preliminary data indicate an effect of row width, by a lower aphid infestation and an earlier presence of predators in 3 m strips compared to 6 m strips. This project contributes with practical as well as scientific knowledge for implementation of strip cropping to support biodiversity and agroecosystem resilience.

Sustainably increasing organic vegetable crop productivity is needed to meet growing demands, considering replacement of conventional animal manures with alternative fertilizers. We investigated the effects of intercropping (IC) and different organic fertilization strategies, and their interactions, on the plant-soil system. A 2-year IC field experiment with white cabbage and beetroot was conducted with two compost-supplemented fertilization strategies (animal-based AF+C; plant-based PF+C) and one control with pig slurry (CONT). Root growth was measured with the minirhizotron method. Overall productivity of intercropping (IC) was lower or similar to that of monocropping (MC) systems with a land equivalent ratio of 0.8 in 2018 and 1.0 in 2019. IC affected rooting intensity in only few soil layers: at harvest (2018), beetroot IC had higher rooting intensity compared to beetroot MC in 0.25–0.75 m soil layer. Mycorrhizal colonization of beetroot roots was increased by 37 % under IC. CONT crops had the highest yield and nitrogen (N) accumulation in 2018. In 2019, yield, N and phosphorous (P) accumulation and soil enzyme activity were higher in the PF+C and CONT conditions than with AF+C. Potential N mineralization was 24–37 % higher under PF+C compared to CONT and AF+C, whereas hot water extractable P was highest under animal-based fertilization strategies (CONT: 8.66 mg kg−1, AF+C: 8.56 mg kg−1) compared to PF+C: 7.99 mg kg−1. Benefits of productivity and N-use-efficiency from complementary root growth and resource use were not found in cabbage-beetroot IC. Instead, displacement of sowing/planting dates in the second year decided the dominating species, supported by mycorrhiza in beetroot. This management practice reduced the level of competition and increased the overall productivity of the IC system compared to 2018. The plant-based fertilization strategy had higher soil fertility as indicated by potential N mineralization and similar P use efficiency and can replace

Lecture for students at AU Master Science course Organic Agriculture – System Analysis, Product Quality and Environment 2022

Seminar given to the vegetable consultants from the advisory company HortiAdvice

This practice abstract gives practical recommendations for crop growth and nutrient dynamics in intercropping systems using different fertilization strategies. The project studied the effects on organic vegetable production in field trials in four European countries. In most cases, yield in intercropping systems was equally high compared to monocropping. Alternative fertilisation strategies maintained or improved soil quality, while not compromising yield.

Working plan for Comcrop composter experimental series by Mariane Lynge, Mesfin T. Gebremikael, Hanne L. Kristensen

Data set of the manuscript Lynge et al. (2022)Production strategies for obtaining high fertilizer value of plant-based fertilizers