Production of apples

Last changed: 06 December 2023

Fertigation with organic nitrogen fertilizers

Project responsible: Helene Larsson Jönsson, the Department of Biosystem and technology, SLU Alnarp.

Project member: Helena Persson Hovmalm, the Department of Plant Breeding, SLU Alnarp.

The aim is to evaluate and optimize the use of organic, liquid N-fertilizers (Vinass and Fontana) in drip irrigation systems. The project focuses on

  • growth,
  • yield,
  • external (color, firmness, appearance) and
  • internal (sugars, organic acids) quality and
  • fruit tolerance to fungal attack during storage.

Our project started in 2016 and will be financed by SLF/PA in cooperation with Kiviks Musteri and Äppelriket, until the end of 2017. We have started field trials both in an organic orchard and in an IP (integrated production) orchard in order to evaluate the potential of liquid organic N-fertilizers at different pest management strategies.

With the grants from SLU EkoForsk during 2018 and 2019, we will be able to run the project for two more years in the organic orchard. As apple trees store nutrients in the biomass, you cannot see the full effect of fertilization strategies until the following year, and these extra two years will therefore increase the scientific value of the project.

The cooperation between SLU, Äppelriket and Kiviks Musteri provides a good platform for the exchange of knowledge between researchers, advisors and growers, so that the results, in addition to scientific publications, also are spread among people working within apple production. Ultimately, our project may lead to a competitive Swedish production of organic apples with fruits of good quality.


Today, both yield and quality is far too low in Swedish organic apple production. The reason behind may be that solid organic fertilizers and manure, which are commonly used fertilizers, release N slowly and therefore N may not be available when the apple trees need it for growth and development. Because of the low quality of the fruit, the storability is reduced and the organic apples are often sold shortly after harvest.