Browsing by Author "Nikkari, Saara"

A field experiment was conducted at Potato Reseach Institute during 1997-2002 in Lammi, Finland. The first aim of the work was to find out the suitability of three- and four-year crop rotation on potato production. The second aim was to investigate the effect of three different tilling methods and four different preceding crops on yield and quality of potato. The tilling methods were autumn and spring ploughing and light cultivation. The preceding crops were barley with straw left in the plots, barley with straw harvested, oat with straw harvested and two-year-grass. There were no differences on yield or quality of tubers between the studied crop rotations. The tuber yield did not differ between the tilling methods or the preciding crops. There was an interaction between all studied rotation and tilling methods. Three-year rotation resulted in approximately 5 % higher tuber yield and 14 % higher marketable yield following spring ploughing and light cultivation in comparison to autumn ploughing. However, four-year rotation resulted in an opposite result, since the tuber yield was 7 % and marketable yield 17 % higher following autumn ploughing in comparison to both spring ploughing and light cultivation. The most effecting factor on tuber quality was the two-year-grass as a preceding crop. Starch content was a little less than one percentage point higher following grass in comparison to all other preceding crops studied. Plant stand was also slightly sparser and tubers were slightly larger following grass in comparison to other preceding crops studied. This was due to grass lumps which caused problems in planting and resulted in uneven plant stand density. There were more green tubers following grass in comparison to other preceding crops studied. The starch content was a little less than one percentage point lower following spring ploughing in comparison to other tilling methods. Common scab was observed somewhat more following spring ploughing. The light cultivation resulted in the highest number of green tubers. Three- and four-year crop rotations seem to fit for potato cultivation, and oat and barley are suitable as preceding crops for potato. Yield is not affected when spring ploughing- and light cultivation is applied with cereals as preceding crops. The two-year-grass is also suitable preceding crop for potato. It increases the tuber starch content, even tough it can decrease the quality. Thus, autumn ploughing is the best option as a tilling method to be used for grass as a preceding crop in potato cultivation.