Bhaniswor Pokhrel

Videnskabelig assistent

Bhaniswor Pokhrel


PhD Project Title: Effects of liquid organic fertilizers on nutrient availability and plant nutrition.


Aarhus University, Faculty of Science & Technology


Department of Food Science


Karen Koefoed Petersen, PhD, Senior Scientist


Jørn Nygaard Sørensen, PhD, Senior Scientist and Hanne Lakkenborg Kristensen, PhD, Associated professor

Project term:

1 December 2013 – 30 November 2016

Masters Degree:

MSc in Agrobiology, Department of Food Science, Aarhus University



The demand for organic fruit and vegetables is increasing day by day worldwide as well as in Denmark. In Denmark, much of the demand is fulfilled by imports. In order to compete with countries that export organic fruit and vegetables to Denmark, Danish organic producers have to increase productivity with superior quality and to extend the growing season by growing in relatively inexpensive tunnels and plastic greenhouses. Nevertheless, organic farmers are facing many problems including nutrient management. Challenges in organic fertilizer management can be; variation in nutrient concentrations, predictability of release and availability, and pH control when growing in restricted volumes. Poor management can result in nutrient accumulation, precipitation or leaching. These factors greatly influence the yield of organic crops compared to conventional. To overcome these problems, application of organic liquid fertilizer with irrigation (fertigation) could be an alternative. In liquid organic fertilizers, nutrients are more readily available and several fertilizers can be combined to meet crop demand. Therefore, the plant needs are more accurately addressed and the use of resources is optimized, accumulation and leaching are avoided and higher yields and better quality can be achieved. However, there are a very low number of certified organic liquid fertilizers available in Denmark. This PhD-project will focus to develop some new organic liquid fertilizers with higher nutrients content from plant and animal biomass fermentation and these fertilizers will test in crops to know their effect on yield and quality.



  • Characterise the influence of different liquid organic fertilisers on nutrient availability, pH and electrical conductivity in the plant root environment.
  • Determine the influence of different liquid organic fertilisers on growth, yield and quality of model crops (parsley, tomato and strawberry).


Research outline

Organic biomasses of different biological origins will be identified for fermentation according to their nutrient composition and C/N ratios. These identified organic sources will be fermented in pilot plants at Green Farm (ethanol) and Department of Engineering (biogas) to produce the organic fertilizers (partly involve). Fertilizer products, both solid and liquid, will be described in terms of content and availability of nutrients. These fertilizers will be tested in parsley, strawberries and tomatoes to know their effect on yield and quality. A detailed study of how the pH, EC and nutrient content of return water and root zone changes will be followed for selected fertilizers in order to combine several fertilizers in a few overall strategies.


Partners of collaboration:

  • Department of Engineering, (AU)
  • HortiAdvice Scandinavia
  • Nursery Jørge og Jensen I/S
  • Økologihaven Aps
  • Økogaarden ApS
  • Green Farm Aps

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