Blueberry response to NPK fertilizers
Plain language summary
La culture du bleuet est peu exigeante mais elle réagit bien aux engrais complets mais nous avons peu d'information sur l'importance de chacun des éléments qui composent l'engrais, soit l'azote, le phosphore et le potassium. Cette étude a permis de démontrer les bienfaits d'appliquer de l'azote à tous les deux ans sur la productivité de la culture tandis que le phosphore et le potassium pourraient être mis au besoin, selon les analyses des feuilles du plant de bleuet.
Abstract
Several studies have shown that the wild lowbush blueberry responded positively to N fertilization. The crop response to P and K is divergent and poorly documented. The objectives of this project were to determine the impact of NPK fertilization on soil chemical properties, leaf nutrient concentrations and fruit yield. The treatments consisted of four rates of N, two rates of P and four rates of K, applied in the spring of the sprout year. Soil pH decreased significantly with increasing N rates, from 4.44 to 4.31 in the soil surface layer and from 4.85 to 4.64 in the 5-20 cm soil layer. Accumulation of P and K were measured in the soil surface. Fruit yield increased significantly (43%) with N fertilization. When N rate was over 60 kg ha-1, fruit yields were limited if no P was added. High K rates limited fruit yield when N rate was over 60 kg ha-1. The leaf N, P and K concentrations increased significantly with NPK rates. Soil P and K content were not significantly related to crop response. Leaf nutrient concentrations were better indicators to reach optimal fruit yield. These results suggest that N fertilization should be applied to each production cycle while P and K fertilizer should be applied according leaf nutrient analysis to maximize fruit yield.