Articles
EVALUATION OF SIX DIFFERENT SOIL TEST PHOSPHORUS EXTRACTION METHODS FOR RELATIONSHIP WITH CRANBERRY
Article number
810_83
Pages
627 – 632
Language
English
Abstract
As with other perennial fruit crops, plant tissue analysis is the standard technique used for assessing nutrient status in cranberry (Vaccinium macrocarpon Ait.). Additionally, the low pH and high iron and aluminum environment in cranberry soils are unlike the chemical conditions for which routinely used soil phosphorus (P) extracts were developed.
There is increasing pressure to base farm nutrient management plans on soil test P, although past studies have shown poor relationships between soil test P and cranberry P response.
Field trials to study cranberry yield response to P fertilizer between 0-34 kg/ha were established on two fields each in Massachusetts and Wisconsin.
From 2004 through 2007, soil samples were collected from replicated plots in each of these four fields.
Four replicates of each soil sample were extracted with six methods: dilute acid, dilute acid plus fluoride (Bray P, current cranberry standard), sodium bicarbonate, ammonium acetate, calcium chloride extraction, and an iron hydroxide impregnated strip (Fe strip). The first four methods are routinely used in soil test laboratories, the fifth has been used less frequently and the sixth uses iron oxide as a sink for P and has shown promise in acid soils.
Sample extraction and analysis for the Fe strip method was only complete for 1 year versus the other five methods where analysis was complete for all years except 2007. Soils from one site were highly organic and there were no statistical differences in soil test P based on P fertilizer rates in this soil.
Of the five extraction methods, only two, the calcium chloride and sodium bicarbonate showed statistically significant relationships between soil test P and P fertilizer application rates for multiple sites in multiple years.
Additionally, when there were significant relationships with these methods, soil test P increases showed good consistency with P fertilizer rate increments.
The soil test P concentrations with these methods were consistently lower than with the Bray method, the current cranberry standard and an acidic extraction, suggesting that the calcium chloride and sodium bicarbonate methods do not over extract plant unavailable P in acidic cranberry soils.
However, there were differences related to the fertilizer trial site and year with these two methods, suggesting that there may not be one best universal extractant for all cranberry soils.
There is increasing pressure to base farm nutrient management plans on soil test P, although past studies have shown poor relationships between soil test P and cranberry P response.
Field trials to study cranberry yield response to P fertilizer between 0-34 kg/ha were established on two fields each in Massachusetts and Wisconsin.
From 2004 through 2007, soil samples were collected from replicated plots in each of these four fields.
Four replicates of each soil sample were extracted with six methods: dilute acid, dilute acid plus fluoride (Bray P, current cranberry standard), sodium bicarbonate, ammonium acetate, calcium chloride extraction, and an iron hydroxide impregnated strip (Fe strip). The first four methods are routinely used in soil test laboratories, the fifth has been used less frequently and the sixth uses iron oxide as a sink for P and has shown promise in acid soils.
Sample extraction and analysis for the Fe strip method was only complete for 1 year versus the other five methods where analysis was complete for all years except 2007. Soils from one site were highly organic and there were no statistical differences in soil test P based on P fertilizer rates in this soil.
Of the five extraction methods, only two, the calcium chloride and sodium bicarbonate showed statistically significant relationships between soil test P and P fertilizer application rates for multiple sites in multiple years.
Additionally, when there were significant relationships with these methods, soil test P increases showed good consistency with P fertilizer rate increments.
The soil test P concentrations with these methods were consistently lower than with the Bray method, the current cranberry standard and an acidic extraction, suggesting that the calcium chloride and sodium bicarbonate methods do not over extract plant unavailable P in acidic cranberry soils.
However, there were differences related to the fertilizer trial site and year with these two methods, suggesting that there may not be one best universal extractant for all cranberry soils.
Publication
Authors
J.R. Davenport, C. DeMoranville, T. Roper
Keywords
Vaccinium macrocarpon, acid soils, iron, aluminum
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