Agronomic and environmental soil phosphorus tests for predicting potential phosphorus loss from Ontario soils
Introduction
Intensification of livestock operations in developed countries over the last few decades has led to the production of large and localized volumes of manure (Sharpley et al., 2004, Maguire et al., 2007, Sims et al., 2000). Application of animal manures to meet the nitrogen requirements for crop growth is a practice that has resulted in excess phosphorus (P) applications and build-up in soils (Leytem et al., 2006). In Ontario, it has been estimated that over 70% of agricultural soils contain adequate to excessive levels of soil test P (Fixen et al., 2010). Elevations in soil P levels can be directly related to the increased potential of soil P loss and thus contributing to eutrophication of surface water (Sims et al., 2000, Sharpley et al., 1996). As a result, there has been an increased research effort worldwide towards developing appropriate environmental soil P tests for identifying soils that are at risk of P losses causing concerns to water quality.
Some agronomic soil P tests (e.g., Olsen-P, Mehlich-3 P, and Bray-1 P), either alone or as an important component of a P index, have been recommended for assessing the risk for soil P loss (Sims et al., 2000). Such P tests, however, were developed to determine the amounts of P that would be available to a crop during the growing season, and may not adequately reflect soil P losses during an episodic events such as rainfall or snowmelt (Allen et al., 2006, Torbert et al., 2002). Soil water extractable P (WEP), Fe-oxide coated filter paper strip P (FeO-P) and various soil P saturation estimations have been proposed to represent the potential for soil P losses due to their strong theoretical foundations for fulfilling risk evaluation (Sharpley, 1993, Breeuwsma and Silva, 1992, Pote et al., 1999).
Selection of an appropriate environmental soil P test for a region should rely on a variety of field experiments (i.e., watershed monitoring and field runoff plots) and/or indoor rainfall simulations with runoff boxes and intact soil columns (Guidry et al., 2006, Kleinman et al., 2004). However, such experimental techniques are time-consuming and labor intensive. Of the various STP methods available, studies conducted in Ontario and beyond have shown that soil WEP is most consistently and highly correlated with dissolved reactive P (DRP) concentrations in surface runoff (Pote et al., 1999, Penn et al., 2006, Wang et al., 2010). This is probably due to the fact that the extracting solution for WEP is the closest to the rainfall water in terms of the ability of releasing P from soil components (Penn et al., 2006). Therefore, the strength of the relationships between agronomic STP or the derived DPS and WEP may to some degree reflect the suitability of these soil P measures as indicators of soil P loss. In fact, many researchers use soil WEP as a surrogate of soil P losses to evaluate the suitability of various STPs and DPSs as indicators of soil P losses (Khiari et al., 2000, Nair et al., 2004, Ige et al., 2005). In order to cost effectively identify a scientifically sound environmental soil P test for a given jurisdictional region, the relationship between various STPs or DPSs and soil WEP should be evaluated across a sufficiently large population of soils from the area in question. The most promising methods should then be further assessed with field and/or indoor simulation studies at a relative small scale. Such analyses would improve our understanding of the relationships between various STP or DPS and soil P loss into surface water at a regional level. A comparison between analyses of a large population of soils and results from field and/or indoor studies of a relatively small scale may show how suitable various STPs and DPSs are for predicting potential soil P losses across this region. Moreover, the comparison would indicate if there is a need to conduct further field/indoor rainfall simulation studies with a wider range of soils. Implicit in the above is the understanding that estimation of a soil's capability to release P to runoff or leaching waters is primarily only the assessment of the source component of a typical P index unless specific P loss relationships are observed for soil types (i.e. say based on textural differences) that would also potentially affect transport mechanisms of P as well.
Ideally, a soil P test method would identify both the soil P status for risk of loss as well as provide an agronomic basis for P application under local conditions. Some forms of STP and DPS may therefore be preferred when assessing the risk of P loss from soils, if they also provide relevant agronomic information. Alternatively, some predominantly environmental soil P tests may also be suitable agronomic tests. However, often little information is available regarding the suitability of predominantly environmental STPs and DPSs for identifying crop requirements for P fertilization. There have been some reports on close relationships between soil P extracted by Mehlich-3, Olsen, Bray-1, and FeO extractants (Menon et al., 1997, Kleinman et al., 2001, Wolf and Baker, 1985, Atia and Mallarino, 2002). Bates (1990) found that soil Olsen P was significantly correlated with other STPs following the order of Mehlich-3 P, Bray-2 P, and Bray-1 P for 88 Ontario soils, although Olsen P was superior for predicting P uptake by test plants. In addition, continuous manure additions not only increase P levels in surface soils but may also change soil P chemistry (i.e. increasing pH and changes in P forms present in soils), which suggests a need to re-evaluate the suitability of various soil P testing methods and their relationships in soils following long periods of manure application (Sharpley et al., 2004).
The objectives of this study were (i) to evaluate the relationships between various STPs (i.e., soil Olsen P, Mehlich-3 P, Bray-1 P, and FeO-P), and (ii) to assess the suitability of these STPs and the derived DPSs as indicators of soil P losses based on their relationships with soil soluble P (WEP) as a preliminary step for identifying potential environmental indices that could be applicable to Ontario soils.
Section snippets
Soil collection
A total of 391 soil samples (0–20 cm) collected across the province of Ontario were analyzed in this study. Among them, 60 soil samples representing six major soil types in the livestock production areas of Ontario were used for the runoff rainfall simulations and leaching studies, as described by Wang et al., 2010, Wang et al., 2012. An additional 138 soil samples collected by Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) and the A&L Canada Laboratories Inc. came from 30 of
General soil properties
The soils selected for the study had a wide range of chemical and physical properties (Table 1). Particle size distributions of these soils ranged from 79 to 902 g kg− 1, from 10 to 626 g kg− 1, and from 25 to 624 g kg− 1 for the contents of sand, silt, and clay, respectively. The organic carbon contents ranged from 10 to 66 g kg− 1. The soil pH ranged from 4.2 to 7.6, although most of the soils were in the neutral or slightly acid range. The levels of soil Olsen P varied from 2 to 269 mg P kg− 1 soil, with
Conclusions
Across all the Ontario soils tested, the strength of the correlations between various STPs followed the order of Mehlich-3 P versus Bray-1 P (r2 = 0.95) > Mehlich-3 P versus FeO-P (r2 = 0.85) > Olsen P versus FeO-P (r2 = 0.80) > Mehlich-3 P versus Olsen P (r2 = 0.77) > FeO-P versus Bray-1 P (r2 = 0.76) > Olsen P versus Bray-1 P (r2 = 0.68). Significant relationships were observed between soil WEP concentrations and various STPs and DPS estimations. Soil FeO-P showed promising potential (r2 = 0.88) as an indicator of P
Acknowledgments
We thank M. Reeb and B. Hohner from the Greenhouse and Processing Crops Research Center, Agriculture and Agri-Food Canada and A&L Canada Laboratories Inc. for their technical assistance; selected Ontario farmers for their collaboration on soil site determination and sampling; and the Nutrient Management Joint Research Program of the Ontario Ministry of Agriculture, Food and Rural Affairs — Ontario Ministry of Environment (Project number: NM8002) for financial assistance.
References (55)
- et al.
A modified single solution method for the determination of phosphorus in natural waters
Anal. Chim. Acta
(1962) - et al.
Relationships between extractable soil phosphorus and phosphorus saturation after long-term fertilizer or manure application
Soil Sci. Soc. Am. J.
(2006) - et al.
Soil and surface runoff phosphorus relationships for five typical USA midwest soils
J. Environ. Qual.
(2006) - et al.
Agronomic and environmental soil phosphorus testing in soils receiving liquid swine manure
Soil Sci. Soc. Am. J.
(2002) - et al.
A phosphate sorption index for soils
J. Soil Sci.
(1971) Prediction of phosphorus availability from 88 Ontario soils using five phosphorus soil tests
Commun. Soil Sci. Plant Anal.
(1990)- et al.
Phosphate fertilization and environmental effects in the Netherlands and the Po region (Italy)
Rep. 57
(1992) Phosphorus extraction with iron oxide-impregnated filter paper (Pi) test
- et al.
Evaluating the Bray P1 test on alkaline, calcareous soils
Soil Sci. Soc. Am. J.
(2008) - et al.
The fertility of North American Soils, 2010
Better Crops Plant Food
(2010)
Using simulated rainfall to evaluate field and indoor surface runoff phosphorus relationships
J. Environ. Qual.
Environmental index for estimating the risk of phosphorus loss in calcareous soils of Manitoba
J. Environ. Qual.
Comparison of Bray-1 and Mehlich-3 tests in high phosphorus soils
Soil Sci.
An agri-environmental phosphorus saturation index for acid coarse-textured soils
J. Environ. Qual.
Interlaboratory comparison of soil phosphorus extracted by various soil test methods
Commun. Soil Sci. Plant Anal.
Evaluation of phosphorus transport in surface runoff from packed boxes
J. Environ. Qual.
Particle size distribution
Phosphorus
The influence of manure phytic acid on P solubility in calcareous soils
Soil Sci. Soc. Am. J.
Chemical Equilibria in Soils
Comparison of Mehlich 3- and Bray 1-extractable phosphorus levels in a Starr clay loam amended with poultry litter
Commun. Soil Sci. Plant Anal.
Soil testing to predict phosphorus leaching
J. Environ. Qual.
Measuring agronomic and environmental soil phosphorus saturation and predicting phosphorus leaching with Mehlich 3
Soil Sci. Soc. Am. J.
Diet modification to reduce phosphorus surpluses: a mass balance approach
J. Environ. Qual.
Correlation of a resin membrane soil phosphorus test with corn yield and routine soil tests
Soil Sci. Soc. Am. J.
Prediction of fertilizer phosphate requirement using the Langmuir adsorption maximum
Plant Soil
Iron-oxide impregnated filter paper (Pi test): II. A review of its applications
Nutr. Cycl. Agroecosyst.
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