The effect of cultivation methods on the yield and biological quality of potato

The effect of organic and conventional methods on the yield and biological quality of potato m two field crop rotations was identified. The field trials were performed m Central-Estonia in Olustvere (58° 33' N, 25° 34' E) during two years and in North-Estonia in Saku (59° 18' N, 24° 39' E) during three years. In Olustvere the following cultivation methods were compared: organic I - without manure, organic II - with cattle manure (at the rate 60 t ha -1 ), and conventional (manure, mineral fertilizers and pesticides were used). In organic cultivation the fertilization with manure increased the potato yield on average 36.5%. At that, the dry matter content in tubers decreased and the nitrate content increased. In conventional farming the yield was 127% higher than in the variant organic II. In organic cultivation the tubers' content of dry matter, starch and minerals was higher than in conventional cultivation. As to the content of reducing sugars, crude protein and nitrates no significant differences were found between the cultivation methods. In Saku, the yields and biochemical composition of potato were compared in trial areas fertilized with plant compost and mineral fertilizers. Equivalent rates of NPK to both trial variants were applied during three years. With compost the yield of potato was on average 32.1% lower than with mineral fertilizers. There were no significant differences in the effect of compost and mineral fertilizers on the biological quality of potato tubers.