Soil nitrogen and phosphorus bioavailability to wild lowbush blueberry produced in Quebec.

Lafond, J. and Ziadi, N. (2013). "Soil nitrogen and phosphorus bioavailability to wild lowbush blueberry produced in Quebec.", Canadian Journal of Soil Science, 93(1), pp. 33-44. doi : 10.4141/CJSS2011-106  Access to full text

Abstract

A better understanding of nitrogen (N) and phosphorus (P) bioavailability in blueberry soils is essential to establish fertilizer recommendations. The objectives of this study were: (i) to evaluate different methods to determine soil ammonium and phosphorus bioavailability to the crop, (ii) to determine the best N and P bio-indicator for blueberry fruit yields and nutrient leave concentrations, and (iii) to establish soil fertility classes. The treatments consisted of four N rates (0, 30, 60 and 90 kg N ha-1) and four P rates (0, 30, 60 and 90 kg P2O5 ha-1). Ammonium in soil was extracted with KCl (N-NH4KCl) and water (N-NP{SUB}4W{/SUB}) and also determined using cation exchange membrane (N-NH4KCl). The soil phosphorus was extracted with Mehlich 3 (P{SUB}M3{/SUB}) and water (P{SUB}W{/SUB}) and using anion exchange membrane (P{SUB}MEA{/SUB}). Soil N and P concentrations decreased during the season with an accumulation of available soil P in the soil surface layer. Soluble fractions of soil N (N-NP{SUB}4W{/SUB} and N-NH{SUB}4MEC{/SUB}) were significantly correlated with leaf N concentration (0.28<r< 0.78) and fruit yields (0.38<r<0.48). The bioavailable P fraction (P{SUB}M3{/SUB}) was significantly correlated with leaf P concentration (r=0.30) and fruit yield (r=0.36). Soil water extractable ammonium and P{SUB}M3{/SUB} are the best indicators of the availability of soil N and P to blueberry crops. From these indicators, critical values beyond which fertilization is no longer required were established at 3.1 mg kg-1 for the N-NP{SUB}4W{/SUB}, 52 mg kg-1 for P{SUB}M3{/SUB} and 0.028 for the molar ratio P{SUB}M3{/SUB}/(Fe+Al) {SUB}M3{/SUB}.

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