Potatoes - quality aspects

In the production of organic potatoes, problems relating to the supply of nutrients and the occurrence of Rhizoctonia are often encountered. The crop has greatest demand for nitrogen for a relatively short period of the growing season. Even a minor surplus of nitrogen early and / or late in the season can have a detrimental effect. An adequate supply of potassium is also of great importance for several quality parameters. Rhizoctonia thrives well on organic soils because of the large amounts of organic matter that are present; the type, level and distribution of this organic matter having a big effect on the amount of damage caused. A better understanding of these central issues is of crucial importance for obtaining good results in organic potato production.

The objective of this project is to develop methods for achieving stability in the production of high quality organic potatoes, with particular attention to securing an adequate supply of nutrients and minimising the damage caused by Rhizoctonia. The basis of these studies is five different management systems: i.e. two levels of slurry, two levels of deep litter, and no animal manure. Within these systems a number of different strategies will be tried: (i) ploughing in manure, or disk harrowing / placement of slurry before planting, (ii) gradual ridging / ridging at planting, loosening the soil to mineralise the nutrients, and (iii) composting / fresh deep litter. These different strategies influence mineralisation and the timing of mineral release, as well as the incidence of Rhizoctonia damage, and potato quality. Quality analyses, yield assessments and soil analyses are used to evaluate these systems and treatments. The suitability of several cultivars is also being assessed, quality and disease resistance being important parameters. These experiments are being conducted in organic rotations at Jyndevad and Foulum Research stations, respectively, and with organic producers.


Summary
Publications


Project title
II.3 Potatoes - quality aspects

Project leader
Jens Peter Mølgaard, Danish Institute of Agricultural Science, Department of Plant Growth and Soil Science, Research Centre Foulum, P.O. Box 50, DK 8830 Tjele
Tel: +45 8999 1840, Fax: +45 8999 1839
E-mail: JensP.Molgaard@agrsci.dk

Project participants
Gunnar Mikkelsen and Søren Holm, Danish Institute of Agricultural Science