Charles Karemangingo 1 , Jacques Lavoie 2 and Chuck Everett 1
Partner: New Brunswick Soil and Crop Improvement Association
Abstract: This study had to reevaluate the response of Shepody and Russet Burbank potatoes to phosphate fertilization in soils having very high P values in order to adjust the New Brunswick P fertilizer recommendations on potato. Two field experiments were carried out in Drummond (for Shepody) and Saint-André (for Russet Burbank) in the North-west of New Brunswick, on soils (humo-ferric Podzols) testing more than 250ppm Mehlich-III phosphorus. Six phosphate fertilizer rates (as diammonium phosphate) varying from 0 to 165 kg P2O5 ha-1 in 33 kg of increments were tested. The total tuber yields of Shepody varied from 33 to above 37 tonnes ha-1. The marketable yields varied from 84 to 89% of the total tuber yields. No differences were detected with regards to the six P rates. Also, the different P rates did not have any significant effect neither on the soil P status nor on the potato petiole phosphorus over the Shepody growth. The variation of the applied P fertilizer rate did not effect neither the tuber specific gravity nor the French fry color reflectance after 150 days of storage in controlled conditions. No conclusion can be made, at this time, from the results obtained with Russet Burbank as this late variety was planted late and harvested early. In general, the results on Shepody tend to confirm that, in soils very high in phosphorus, optimum potato tuber yields and quality can be obtained from the application of reduced phosphate fertilizer rates.
1 Land Development Branch, New Brunswick Department of Agriculture, Fisheries and Aquaculture, P.O. Box 6000, Fredericton, NB, E3B 5H1
2 Potato Development Center, New Brunswick Dept. of Agriculture, Fisheries and Aquaculture, 39 Barker Lane, Wicklow, NB, E7L 3S4