Charles Karemangingo1, Jacques Lavoie2 , Charles Everett1 and Brian Sanderson3
Partner: New Brunswick Potato Agency and New Brunswick Soil and Crop Improvement Association
Abstract: This study re-evaluates the potato response to P fertilizer in soils containing very high P levels. Two experiments, one with Shepody and another with Russet Burbank, were carried out in Fredericton on soils testing about 110 ppm P (Mehlich-III). Six P fertilizer rates (as diammonium phosphate) varying from 0 to 200 kg P2O5 ha-1 in 40 kg of increments were tested. The total tuber yields of 30 and 26 tonnes ha-1 were harvested for Shepody and Russet Burbank, respectively. The marketable yields represented 93 and 69% of the total yields of the two respective varieties. No differences were detected in relation to the P rates with regards to the yields, the specific gravity, the size, and the fry color over the winter period. At the early steps of the growth, petiole P content increased with the increase of P rates for the two varieties. No differences were observed 10 weeks after planting. Similarly, residual soil P content in the fall increased with the increase of P rates regardless of the potato variety. These results support those obtained in 2000 which indicated that Shepody and Russet Burbank do not respond to P fertilizer in P-saturated soils. It is therefore recommended that soil P saturation be considered a valid factor for P management in potato soils.
1Land Development Branch, Department of Agriculture, Fisheries and Aquaculture, P.O.Box 6000, Fredericton; NB, E3B 5H1
2Potato Development Center, Department of Agriculture, Fisheries and Aquaculture, Wicklow, NB, E7L 3S4
3Potato Management, Research Branch, Agriculture and Agri-Food Canada, Charlottetown, C1A 7M8 PEI