Organic potato cultivation Thomas F. Döring, Humboldt-Universität zu Berlin and University of Bonn, Germany; and Derek H. Lynch, Dalhousie University, Canada

1 Introduction

2 Rotation and diversification

3 Breeding, seed potatoes and planting

4 Tillage and weed control

5 Nutrient management and soil fertility

6 Irrigation

7 Regulation of diseases and pests

8 Conclusion

9 Where to look for further information

10 References

1.1 An introductory example At the Wiesengut farm in Germany’s Midwest, an experimental organic farm run by the University of Bonn, the crop rotation plan schedules potatoes to be grown after a ley of red clover (Trifolium pratense) and grass (Haas and Köpke, 2002; Dahn, 2013). The ley leaves a relatively large amount of plant residues and contributes to a good soil structure. Further, because the ley is cut several times to provide feed for the farm’s Limousin cattle, it helps in suppressing annual weeds. The red clover fixes nitrogen which can then be used by the potato crop. In order to prevent nitrate losses through leaching the ley is kept over winter and incorporated into the soil in spring just before planting the potato. The farm uses pre-sprouting of the seed potatoes to optimize the crop’s growth period before the fungal pathogen late blight (Phytophthora infestans) occurs in the summer. When moist and warm weather conditions coincide with the main growth period of the crop, copper preparations are applied at a maximum of 3 kg ha−1 to limit spreading of late blight infections. In cases of mass occurrence of Colorado potato beetle (CPB) (Leptinotarsa decemlineata), the crop is treated with the biological insecticide neem which affects larvae and can reduce defoliation (Kühne, 2010).