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Sindhuja Shanmugam

Sindhuja Shanmugam
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PhD project: Nitrogen use-efficiency, soil fertility and root competition in intercropped vegetable systems with plant-based fertilizer strategies

University: Aarhus University

Department: Department of Food Science

Supervisor: Hanne Lakkenborg Kristensen, Associate Professor, Department of Food Science, AU

Co-supervisor: Margita Hefner, PhD student, Department of Food Science, AU

Project term: 01.12.2018 – 30.11.2021

Master’s degree: M.Sc. (Agro Environmental Management), Aarhus University, Denmark



Vegetable production often has high leaching losses of nitrate to the environment due to high fertilizer demand, low nitrogen (N) use efficiency and incorporation of N rich plant residues. The plants do not take up all the nitrogen supplied, and the excess mineral N in the soil tends to get lost by leaching and other pathways. This N poses some serious threats to the environment by contribution to global warming, eutrophication and groundwater pollution. To avoid these threats we need to improve the nitrogen use efficiency (NUE) of the cropping system. Modified agronomic practices like intercropping and improved plant-based fertilizer strategies can be used to achieve better NUE, soil fertility and biodiversity.



The aim is to increase our understanding of root and soil interactions in intercropped vegetable systems subjected to new fertility strategies based on pretreated organic plant residues. This knowledge will be used to develop sustainable and eco-friendly cropping systems with less N loss, and can support the organic vegetable producers.


Research outline

Field trials are conducted in a long and a short season vegetable intercropping system: white cabbage-beet root, pointed cabbage-faba bean. The experiments will focus on root competition, plant and root growth, NUE, crop yield and soil fertility in these cropping systems. Sole cropping systems are used for comparison. In addition, three fertilizer strategies are tested in the white cabbage-beetroot intercropping system: 1) conventional liquid manure, 2) plant-based fertilizers and compost, 3) a mixture of plant-based compost and animal manure, to see their effect on nitrogen mineralisation rate, plant nutrient availability, crop yield and nutrient uptake, soil fertility and microbial activity. This research is linked to the SUREVEG project: Strip cropping and recycling of waste for bio diverse and resource-efficient intensive vegetable production (Horizon2020 CORE organic COFUND)


Partners of Collaboration

  • ILVO Institute for Agricultural and Fisheries Research, Belgium
  • Louis Bolk Institute, Netherlands
  • Wageningen University, Netherland
  • CREA - Centro Agricoltura e Ambiente, Italy
  • LUKE Natural Resources Institute Finland
  • UPM School of Agricultural Engineering, Spain
  • INAGRO, Belgium
  • UEF University of Eastern Finland
  • Aarhus University, Department of Bioscience, Denmark
  • UPM Centre for Automation and Robotics, Spain
  • Institute of Horticulture, Latvia

ID: 4145163