Soil Science Society of America Journal 66:2033-2039 (2002)
© 2002 Soil Science Society of America
DIVISION S-8—NUTRIENT MANAGEMENT & SOIL & PLANT ANALYSIS
Measuring Agronomic and Environmental Soil Phosphorus Saturation and Predicting Phosphorus Leaching with Mehlich 3
R. O. Maguire* and
J. T. Sims
Dep. Plant and Soil Sci., Univ. of Delaware, Newark, DE 19717-1303
* Corresponding author (rmaguire{at}udel.edu)
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ABSTRACT
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The role that soil testing can play in identifying agricultural soils with an increased potential for P loss is an important topic. Our research compared the Mehlich 3 P saturation ratio (M3-PSR) with the ammonium oxalate degree of P saturation (DPSox), and the M3-PSR was then evaluated for predicting agronomic and environmental soil P saturation thresholds. Intact soil columns (15-cm diam, 20 cm deep) and soil samples were collected from five soil series that ranged in soil texture, chemical properties, and Mehlich 3 P. The soils were analyzed for pH, organic matter (OM) and oxalate and Mehlich 3 extractable P, Al, and Fe. Each intact column was leached with the equivalent of 5 mm of rainfall and resulting leachate analyzed for P. Mehlich 3 extractable Al, Fe, and P were closely related to oxalate extractable Al, Fe, and P, although Mehlich 3 extracted only a small amount of Fe compared with oxalate. The M3-PSRs, calculated as the molar ratios of Mehlich 3 extractable P/[Al + Fe] (ratio I) and P/Al (ratio II), were well correlated to each other and to DPSox. All three P saturation measurements showed a threshold or change point above which the concentration of P in column leachate increased rapidly. Both the agronomic optimum M3-PSRs and the environmental limit suggested in the Netherlands for DPSox (25%) were below the observed change point. The M3-PSR measured in a single Mehlich 3 extraction shows excellent promise for identifying soils that represent an increased risk for P leaching losses.
Abbreviations: PM3, AlM3, and FeM3, Mehlich-3 extractable P, Al and Fe • M3-PSR, Mehlich 3 P saturation ratio I, P saturation calculated as PM3/[AlM3 + FeM3] • Mehlich 3 P saturation ratio II, P saturation calculated as PM3/AlM3 • Pox, Alox and Feox, acid ammonium oxalate extractable P, Al and Fe • DPSox, degree of P saturation calculated as (Pox,/0.5[Alox + Feox]) x 100 • OM, organic matter
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INTRODUCTION
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AN ADEQUATE SUPPLY OF P is essential for optimum crop growth and profitable agriculture. However, long-term manure applications from intensive animal feeding operations in certain geographic areas have led to increases in soil P concentrations, often above agronomic levels (Sims et al., 2000). Losses of P from agricultural soils have now been identified as one of the major causes of decreased surface water quality (USEPA, 2000; Boesch et al., 2001). There is an ongoing discussion within the scientific community as to the role that soil testing can play in the risk assessment for P losses from agricultural soils (Sims et al., 2000). Comprehensive risk assessment tools such as the "P Site Index," which take many site factors into account, such as slope, soil characteristics and P management factors, will almost certainly be more useful than soil testing alone, but soil testing still has an important role to play in evaluating the potential for P losses from agricultural soils (Gburek et al., 2000; Schoumans and Groenendijk, 2000; Sims et al., 2000).
The degree of P saturation (DPS) of soils, calculated from a single extraction with acid ammonium oxalate (DPSox), has been suggested as an indicator for the risk of P loss from agricultural soils (Breeuwsma et al., 1995; Hooda et al., 2000; Maguire et al., 2001b). The DPSox was first proposed for acidic sandy soils, but has also been shown to be a good predictor for P availability in acidic soils with high clay and OM contents in Ireland (Maguire et al., 2001a). It has been shown that only small amounts of P are weakly bound in soils below a certain DPS threshold, but weakly bound P increases rapidly above this threshold (Hooda et al., 2000; Pautler and Sims, 2000). The DPSox threshold is generally above agronomically optimum soil test P values and, therefore, if agricultural soils are below this DPSox threshold, then adequate crop P supply and environmental protection can both be achieved (Pautler and Sims, 2000). However, the oxalate extraction is not a routine soil test and thus DPSox values are not widely available. Therefore, Khiari et al. (2000) suggested using a soil P saturation index calculated from the Mehlich 3 soil test, which is the routine soil test in many U.S. states and elsewhere. Khiari et al. (2000) reported that the Mehlich 3 P/Al ratio was useful for predicting both potato crop P requirements and an environmental P threshold, above which excess P will be lost from a soil to surface or ground waters, in acidic coarse textured soils in Quebec, Canada.
Until recently, it was considered that P losses from soils through subsurface flow–leaching were not significant compared with losses via surface pathways. However, recent research has demonstrated that P losses from agricultural soils through subsurface pathways can be substantial. For example, Sims et al. (1998) suggested that subsurface flow on the Delmarva Peninsula in the USA can play an important role in P losses from agriculture. In the UK, monolith lysimeter studies showed that subsurface losses of P from agricultural soils can occur at concentrations sufficient to cause eutrophication in surface waters (Turner and Haygarth, 2000). Despite the ability of subsoils to retain P leached from topsoils, and the important role of preferential flow pathways in subsurface P movement, significant relationships have been found between soil test P values and subsurface P losses. For example, Schoumans and Groenendijk (2000) recognized the importance of P losses in subsurface flow in noncalcareous sandy Dutch soils and reported an exponential increase in solution P concentration with increasing DPS. Leinweber et al. (1999) also showed that P concentrations in leachate were well correlated to the soil DPS.
As it is unlikely that DPSox values will ever be widely available for agricultural soils, the first objective of this study was to evaluate the Mehlich 3 soil test for measuring soil saturation with P, in comparison with DPSox. As Mehlich 3 is already a widely used soil test, reporting the Mehlich 3 soil saturation with P would be a relatively easy step for soil testing laboratories already using the Mehlich 3 extraction. For P loss assessments with the M3-PSR, it is critical that the relationship between soil test values and potential P losses is well understood. Therefore, the second objective was to determine the ability of the M3-PSR to predict P losses from soils, in leaching. The third objective was to convert agronomic optimum Mehlich 3 P into M3-PSRs for selected soil series and compare these with suggested M3-PSR thresholds for environmental protection.
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MATERIALS AND METHODS
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Soil Selection and Sample Collection
Five Delaware soil series with a range of chemical and physical properties, representing the dominant agricultural soil groups in Delaware, were selected for this study: Butlerstown (fine-silty, mixed, mesic, Typic Fragiudults), Evesboro (mesic, coated, Typic Quartzipsamments), Matapeake (fine-silty, mixed, mesic, Typic Hapludults), Pocomoke (coarse-loamy, siliceous, thermic, Typic Umbraquults), and Sassafras (fine-loamy, siliceous, mesic, Typic Hapludults) (Table 1). For each soil series, soil test data provided by farmers were used to select soils with a range in soil test P values. Undisturbed soil columns were collected on the basis of the method of McDowell and Sharpley (2001b). For each soil type, 21 columns were sampled by driving 15-cm-diam polyvinylchloride (PVC) pipes, coated on the inside with paraffin wax to seal between the soil and the pipe, 20 cm into the ground. Each of the 21 columns represented a different soil test P. Before the undisturbed columns were removed from the soil, six soil cores (2-cm diam) were collected to a depth of 20 cm from immediately outside the columns and aggregated. To collect leachate water from the columns, holes were drilled into 15-cm-diam PVC endcaps and a short tube filled with glass wool was glued into this hole. The columns were inserted into the endcaps, with sand placed in the space between the soil and the endcap. The capped columns were placed in racks in a greenhouse, prewet by adding excess water and left to drain to field capacity for 2 d. The equivalent of 5 mm rainfall (as deionized water) was then added to the top of the lysimeters and leachate was collected for the following 24-h period. Four leaching events were carried out on successive days with each column. The first leaching event produced unequal amounts of leachate from the columns, probably because of incomplete soil saturation in some cases, but leachate volume became stable after this (data not shown). Therefore the concentration of P in leachate water from the second leaching event is presented in this paper, as it represented the first stable leaching event after the soils were sampled. Leachate P concentrations were similar in leaching events 2, 3, and 4, as described by Maguire and Sims (2002). The number of columns used for each soil series varied slightly because (i) a few columns deteriorated during the leaching process and leachate could not be collected and (ii) additional columns were collected from some soil series where there was not a good range in soil test P (Table 1).
Leachate and Soil Preparation and Analysis
Before analysis, all soil samples were dried and ground to pass through a 2-mm sieve and all column leachate was filtered through 0.45-µm membranes (Millipore Corp., Bedford, MA). All soils were analyzed for pH at a soil to water ratio of 1:1 and OM by loss on ignition, following the standard methods of the University of Delaware Soil Testing Laboratory (Sims and Heckendorn, 1991). Mehlich-3 P, Al and Fe (PM3, AlM3, and FeM3) were extracted at a soil:0.2M CH3COOH + 0.25M NH4NO3 + 0.015M NH4F + 0.013M HNO3 + 0.001M EDTA ratio of 1:10, and filtered through Whatman #2 filter paper (Mehlich, 1984). Acid ammonium oxalate P, Al and Fe (Pox, Alox, and Feox) were extracted at a 1:40 soil: 0.2M acid ammonium oxalate (pH 3) ratio in the dark (McKeague and Day, 1966). The oxalate and Mehlich-3 extracts were analyzed for P, Al and Fe by inductively coupled plasma atomic emission spectroscopy (ICP-AES); the filtered leachate was analyzed for P colorimetrically by the molybdate blue method of Murphy and Riley (1962).
The DPSox was calculated from the acid ammonium oxalate extractable P, Al, and Fe as described by Breeuwsma et al. (1995) as follows:
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where Pox, Alox, and Feox were in mmol kg-1. The M3-PSR was calculated from a single Mehlich 3 extraction in two ways, with PM3, AlM3, and FeM3 in mmol kg-1. First, by including PM3, AlM3, and FeM3:
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and second, by including PM3 and AlM3 in the DPS ratio calculation, but not FeM3 (Khiari et al., 2000):
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The agronomic optimum Mehlich 3 P value for most crops in Delaware is 50 mg P kg-1 (Sims et al., 2001), equivalent to 50/31 mmol P kg-1. The agronomic optimum M3-PSR I for each soil series was calculated from this agronomic optimum value and the average [Al + Fe] for each soil series by means of Eq. [2], as follows (all values expressed in mmol kg-1):
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The agronomic optimum M3-PSR II could be calculated by simply removing FeM3 from Eq. [4].
Statistical Analyses
For the relationships between leachate P concentration and DPSox or M3-PSR, a split line model was used to determine change points, as described by McDowell and Sharpley (2001a), with the Statistical Analysis System, Version 8 (SAS Institute, 1998). The split line model describes separate linear relationships on either side of a change point. All other statistical analyses were carried out with the Data Analysis tool pack in Microsoft Excel 2000 (Microsoft, Seattle, WA).
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RESULTS AND DISCUSSION
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Soil pH and Organic Matter Contents
The pH values of the soils were slightly acidic as is common in the mid-Atlanic region of the USA (Table 1). The Pocomoke soil had a mean pH of 5.2, which was lower than the mean pH values of the other four soils that ranged from 5.7 to 6.3. In Delaware, so called "black" soils with an OM content >60 g OM kg-1 are assigned a lower target pH for most crops than that assigned for comparable soils with a lower OM content (Sims and Gartley, 1996). The Pocomoke series was the only black soil in this study, and the mean OM content of the Pocomoke soils in this study was 61 g OM kg-1. This lower target pH is due to OM ameliorating some of the negative effects of excessive soil acidity, such as Al toxicity (Pierzynski et al., 2000).
Phosphorus, Aluminum and Iron Contents of the Soils
The agronomic optimum Mehlich 3 P value for most crops grown in Delaware, USA, is 50 mg Mehlich 3 P kg-1 (Sims et al., 2001). Although the Mehlich 3 extracts were analyzed by ICP-AES, which is routine in Delaware and elsewhere, it should be noted that some areas use colorimetric analysis of Mehlich 3 extracts. Colorimetric analysis of extracts generally results in lower P values than ICP analysis (Eliason et al., 2001). For each soil type, columns were collected that ranged in Mehlich 3 P concentration from below this agronomic optimum to far above it, indicating the buildup of soil P above agronomic levels in many cases. Only the Sassafras soil, for which the lowest Mehlich 3 P was 79 mg kg-1, had no sample below the agronomic optimum (Table 2). The mean Mehlich 3 P of the Butlerstown series was less than half the mean Mehlich 3 P of any of the other soil series, despite efforts to collect soils with high P levels for all series. Butlerstown soils with P levels as high as those from the other series were rare on the farms studied, probably due to the Evesboro, Matapeake, Pocomoke, and Sassafras soils coming from areas of intensive animal agriculture, while the Butlerstown soil came from an arable farm. Arable farms can balance nutrient inputs through fertilizers, with nutrient outputs in crops, while the increasing trend towards intensive animal operations on relatively small areas of land can lead to nutrient applications to agricultural land in excess of crop requirements and the subsequent buildup of P in the soils (Beegle et al., 2000; Sims et al., 2000). Oxalate extractable P was greater than Mehlich 3 P, but followed the same pattern among the soils (Pocomoke > Matapeake > Sassafras > Evesboro > Butlerstown).
The mean Mehlich 3 and oxalate extractable Al were greatest in the Pocomoke soil (1718 mg Al kg-1 and 2952 mg Al kg-1, respectively) and smallest in the Evesboro soil (683 mg Al kg-1 and 604 mg Al kg-1, respectively) (Table 2). The high value of extractable Al in the Pocomoke soil may be due to its high OM content, as OM can increase the amorphous nature, and hence extractability, of Al (Maguire et al., 2000). Mehlich 3 and oxalate extractable Fe in the two silt loam soils (Butlerstown and Matapeake) were at least twice that in the three sandy loam soils.
Relationships between Mehlich 3 and Acid Ammonium Oxalate Extractable Aluminum, Iron, and Phosphorus
Extractable AlM3, FeM3 and PM3 were closely related to Alox, Feox and Pox with the coefficient of determination for Al (r2 = 0.93***) slightly higher than those for Fe (r2 = 0.87***) and P (r2 = 0.80***; Fig. 1)
. The greatest coefficient of determination in the relationship between AlM3 and Alox was for a power regression (r2 = 0.93***), rather than a linear regression (r2 = 0.89***), which suggests that the ability of Mehlich 3 to extract Al, relative to oxalate, decreased at higher values of extractable Al. However, for the relationship between FeM3 and Feox, the greatest coefficient of determination was for a linear regression (r2 = 0.87***), rather than a power regression (r2 = 0.82***), and the same was true for P with coefficients of r2 = 0.80*** and r2 = 0.73***, respectively. Oxalate was able to extract greater amounts of Al and Fe from the soils than Mehlich 3, especially at higher Al and Fe soil concentrations, and extracted about twice as much P (Fig. 1). Compared with oxalate, Mehlich 3 was a poor extractant for Fe relative to Al and P, as when averaged for all soils, the mean FeM3: mean Feox ratio was only 0.26, while the ratio of mean AlM3: Alox was 0.80 and mean PM3:Pox was 0.54. Regression analysis of P sorption versus oxalate extractable Fe and Al has shown that it is important to include both Al and Fe when the oxalate extract is used to measure the DPSox of a soil (van Riemsdijk et al., 1984; Maguire et al., 2001a). However, on average for all soils, FeM3 made up only 9 ± 16% of mean (AlM3 + FeM3). This is similar to the results of Khiari et al. (2000), who found that mean FeM3 made up 11.6 ± 6.3% of mean (AlM3 + FeM3) in acidic coarse-textured Canadian soils.
Comparison of the Mehlich 3 Phosphorus Saturation Ratio I and II
Although FeM3 made up only 9 ± 16% of mean [AlM3 + FeM3], we plotted the M3-PSR I, calculated using PM3, AlM3, and FeM3 (Eq. [2]), against the M3-PSR II, calculated using PM3 and AlM3, but not FeM3 (Eq. [3]), to test if the relatively small proportion of FeM3 compared with [AlM3 + FeM3] was consistent across the soils (Fig. 2)
. There was a highly significant regression (r2 = 0.99***) between the M3-PSR I and the M3-PSR II (Fig. 2), confirming that the relationship between the two M3-PSRs was consistent across the range in soil textures and properties used in this study (Tables 1 and 2). The regression equation in Fig. 2 (y = 1.21x - 0.015) is almost identical to the regression equation y = 1.17x obtained by Khiari et al. (2000), for sandy soils only which had a greater range in organic matter, and that of y = 1.13x - 0.003 reported by Sims et al. (2002). Maguire et al. (2001a) showed that the DPSox was applicable to acidic Irish soils with a range of textures, not just acidic coarse textured soils which were used in early work on the DPSox by van Riemsdijk et al. (1984). The U.S. soils used in this study ranged in texture from silt loams to sandy loams, indicating that the M3-PSR extracts similar proportions of Al and Fe from soils with a wider range in textures than the coarse textured soils used by Khiari et al. (2000). However, as Mehlich 3 was a poor extractant for Fe relative to Al, in comparison with the oxalate extract, Mehlich 3 may not be useful for measuring the P saturation ratio in high pH soils, or other soils where Fe oxides play a more important role in P sorption than Al (Solis and Torrent, 1989).
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Fig. 2. Relationship between the Mehlich 3 P saturation ratio I, calculated as the molar ratio P/[Al + Fe], and the Mehlich 3 P saturation ratio II, calculated as the molar ratio P/Al.
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The Mehlich 3 Phosphorus Saturation Ratio Versus the Oxalate Degree of Phosphorus Saturation
Much research has been conducted on the value of DPSox as an environmental soil test (van Riemsdijk et al., 1984; Breeuwsma et al., 1995; Hooda et al., 2000; Pautler and Sims, 2000; Maguire et al., 2001a, b). As noted earlier, we hypothesized that the M3-PSR may be a more convenient method that could be widely adopted by routine soil testing labs. Therefore we compared the M3-PSR I and M3-PSR II with DPSox for all soils (Fig. 3a and b) . A power regression produced significantly greater coefficients of determination for the M3-PSR I and M3-PSR II versus DPSox (r2 = 0.94*** and 0.94***, respectively), compared to a linear regression (r2 = 0.87*** and 0.82***, respectively). Breeuwsma et al. (1995) reported a DPSox limit of 25% in the soil profile above the mean high water table in the Netherlands should be used to prevent excessive losses of P by leaching (0.10 mg P L-1). It should be noted that the mean high water table will be site specific and the soils for our study were taken from the top 20 cm. This suggested DPSox limit of 25% is equivalent to 0.062 M3-PSR I and 0.068 M3-PSR II (Fig. 3a and b, respectively). Khiari et al. (2000) calculated a M3-PSR II limit equivalent to 0.15 on the basis of the DPSox limit of 25%. The limit of 25% was based on DPS(%) = Pox/
[Alox + Feox] where = 0.5; however, Khiari et al. (2000) used an value of 0.66. If Khiari et al. (2000) had used = 0.5, then they would have calculated a M3-PSR II limit equivalent to 0.10, closer to our value of 0.068. Our value is also similar to the M3-PSR ratio of 0.086, that can be calculated for a DPSox value of 25% from the work of Sims et al. (2002).
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Fig. 3. Relationship between the oxalate degree of P saturation, calculated on a molar basis as DPSox = (P/0.5[Al + Fe]) x 100% and (a) the Mehlich 3 P saturation ratio I, calculated as the molar ratio P/[Al + Fe] and (b) the Mehlich 3 P saturation ratio II, calculated as the molar ratio P/Al. Conversion of the oxalate environmental limit, suggested in the Netherlands, of 25% into both Mehlich 3 P saturation ratios is shown.
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Relating the Oxalate Degree of Phosphorus Saturation and Mehlich 3 Phosphorus Saturation
Ratios to Phosphorus Losses in Leachate
To evaluate the potential of DPSox, M3-PSR I, and M3-PSR II as environmental soil tests, the concentration of P in leachate water from undisturbed soil cores was compared with both the DPSox (as this has been evaluated in other studies) and to the M3-PSR II (Fig. 4a and b
, respectively). The M3-PSR I would give almost identical results to the M3-PSR II, as they were so well correlated to each other (Fig. 2). The concentration of P in the leachate water frequently exceeded concentrations required to cause eutrophication in surface waters. It should be noted that high P concentrations in the leachate do not necessarily mean that this concentration of P will reach surface waters, as interactions with subsoils and connectivity to surface waters will play an important role (Gburek et al., 2000; Maguire et al., 2001b). However, if the M3-PSR can successfully quantify soil characteristics that increase the potential for P loss, then it may be possible to incorporate it into a P loss assessment tool, such as the P site index reported by Gburek et al. (2000).
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Fig. 4. Relationship between the concentration of P in leachate water and (a) the oxalate degree of P saturation, calculated as DPSox = (P/0.5[Al + Fe]) x 100%, where P, Al and Fe are in mmol kg-1 (including the environmental limit suggested in the Netherlands) and (b) the Mehlich 3 P saturation ratio I (reproduced from Maguire and Sims, 2002), calculated as the molar ratio P/[Al + Fe] (including the equivalent environmental limit suggested in the Netherlands from Fig. 3a and the highest and lowest agronomic optimum Mehlich 3 P saturation ratios, which were for the Evesboro and Pocomoke series respectively. The equations for the lines above and below the change point exclude the two outliers).
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On the basis of a split line model, the P concentration in leachate remained low for almost all samples below a DPSox change point of 
56%, but above this DPSox, leachate P concentration increased rapidly (Fig. 4a). This is analogous to the "change point" first reported by Heckrath et al. (1995), who found a rapid increase in P in tile drains above a threshold Olsen soil test P value of 60 mg kg-1. This value of 56% is similar to the range of change points, equivalent to DPSox ( = 0.5) values of 36 to 56%, for the relationship between DPSox and leachate P reported by McDowell and Sharpley (2001b) for several Pennsylvania (USA) soils. Research in the Netherlands provided a value of 25% DPSox in soils above the mean high water table to maintain the P concentration in leachate water below 0.10 mg P L-1, and this limit was well below this change point (Schoumans and Groenendijk, 2000). This indicates that environmentally significant leaching can occur well below the change point.
A similar pattern of higher P concentrations in leachate water above a change point was observed for the M3-PSR I (Fig. 4b). However, the coefficient of determination was much greater for the relationship between leachate P and the M3-PSR I (r2 = 0.78*** or 0.87*** without two outliers), than between leachate P and DPSox (r2 = 0.46***), indicating that the M3-PSR I was better at predicting P losses in leachate. The two outliers were from the Pocomoke series, as the Pocomoke soils retained P more strongly than the other soil series, probably because of their high Al and OM contents and low pH (Tables 1 and 2), as described for these soils by Maguire and Sims (2002). It should also be noted that apart from the Pocomoke series, only the Matapeake and Evesboro series had soils with P saturation above the change point, so further research is required before extrapolating these results to a wide range of soils. Phosphorus concentrations in leachate tended to increase rapidly above a M3-PSR I change point of 0.23 (excluding the two Pocomoke outliers), but tended to remain low below this ratio.
The agronomic optimum soil test P can be converted into an agronomic optimum M3-PSR I for each soil series (Eq. [4]). The agronomic optimum M3-PSR I is different for each soil series, depending on the mean [AlM3 + FeM3] for the series, with greater mean [AlM3 + FeM3] leading to a lower agronomic optimum M3-PSR I for that series. The agronomic optimum Mehlich 3 P value for Delaware is 50 mg kg-1 for most crops in all soils, and the agronomic optimum M3-PSR is a way of showing how the saturation of soils at agronomic optimum Mehlich 3 P, varies in soils with different contents of [AlM3 + FeM3]. As the Evesboro soil had the lowest and the Pocomoke soil had the highest [AlM3 + FeM3] concentrations on a molar basis (Table 2), the Evesboro and Pocomoke soils had the lowest (0.024) and greatest (0.058) optimum M3-PSR Is, respectively (Fig. 4b). Thus, the agronomic optimum M3-PSR I for both the Pocomoke and Evesboro soils, and therefore the rest of the soils studied here, is below the M3-PSR that is equivalent to the DPSox limit of 25% proposed for the Netherlands (equivalent Mehlich P saturation ratio = 0.062) and well below the change point of 0.23 above which P concentrations in leachate start to increase rapidly.
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CONCLUSIONS
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As concerns in the USA, Europe, and elsewhere about excessive losses of P from agricultural land continue to intensify, there is a need for science-based evaluations of P loss from agricultural and other soils. Research on the soil DPSox, based on a single extraction with acid ammonium oxalate for P, Al, and Fe, has shown that DPSox is a useful aid in estimating the potential for P losses from soils to surface waters. However, the oxalate extraction is not a routine procedure in most soil testing laboratories, so it is unlikely to be used outside research on a large scale. The Mehlich 3 soil test is a common procedure carried out in many soil test laboratories and represents a possible alternative to the oxalate extraction for estimating soil saturation with P. Including Al and Fe analyses on the Mehlich 3 extract for calculation of the M3-PSR I, would be a relatively small extra step for many soil testing laboratories. Our results showed that the M3-PSR I and II, calculated from only Mehlich 3 extractable P and Al (and Fe for ratio I), were closely related to DPSox for five acidic soils with a wide range of textures, OM and extractable P, Al, and Fe. Both DPSox and the M3-PSR I were able to identify a change point above which P losses in leachate increased rapidly, although the coefficients of determination indicated that the M3-PSR I was better than DPSox at predicting losses of P in leachate. However, the Pocomoke soil did not show increased leaching above the change point, possibly because of the high Al and OM contents and low pH of these soils. Translating the DPSox, suggested for environmental protection in the Netherlands, into M3-PSR I, showed that agronomic optimum Mehlich 3 extractable P was below this environmental limit for all soils. Past research has shown that the Mehlich 3P II is useful for predicting crop P requirements. Our research shows that the M3-PSRs I and II also have great potential as indicators for soil P loss potential, that can possibly be incorporated into a more comprehensive P loss assessment tool such as the P site index.
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NOTES
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Published as Paper No. 1709 in the Journal Series of the Delaware Agricultural Experiment Station.
Received for publication November 12, 2001.
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REFERENCES
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- Beegle, D.B., O.T. Carton, and J.S. Bailey. 2000. Nutrient management planning: Justification, theory, practice. J. Environ. Qual. 29:72–79.[Abstract/Free Full Text]
- Boesch, D.F., R.B. Brinsfield, and R.E. Magnien. 2001. Chesapeake Bay eutrophication: Scientific understanding, ecosystem restoration, and challenges for agriculture. J. Environ. Qual. 30:303–320.[Abstract/Free Full Text]
- Breeuwsma, A., J.G.A. Rijerink, and O.F. Schoumans. 1995. Impact of manure on accumulation and leaching of phosphate in areas of intensive livestock farming. p. 239–249. In K. Steele (ed.) Animal waste and the land-water interface. Lewis Publishers-CRC Press, New York.
- Eliason, R., J.L. Lamb, and G.W. Rehm. 2001. Colorimetric and ICP measurement of P extracted by the Mehlich-3 procedure. Agron. Abstr. CD-ROM, ASA, CSSA, and SSSA, Madison, WI.
- Gburek, W.J., A.N. Sharpley, L Heathwaite, and G.J. Folmar. 2000. Phosphorus management at the watershed scale: A modification of the phosphorus index. J. Environ. Qual. 29:130–144.
- Heckrath, G., P.C. Brookes, P.R. Poulton, and K.W.T. Goulding. 1995. Phosphorus leaching from soils containing different phosphorus concentrations in the Broadbalk experiment. J. Environ. Qual. 24:904–910.[Abstract/Free Full Text]
- Hooda, P.S., A.R. Rendell, A.C. Edwards, P.J.A. Withers, M.N. Aitken, and V.W. Truesdale. 2000. Relating soil phosphorus indices to potential phosphorus release to water. J. Environ. Qual. 29:1166–1171.[Abstract/Free Full Text]
- Khiari, L., L.E. Parent, A. Pellerin, A.R.A. Alimi, C. Tremblay, R.R. Simard, and J. Fortin. 2000. An agri-environmental phosphorus saturation index for acid coarse-textured soils. J. Environ. Qual. 29:1561–1567.[Abstract/Free Full Text]
- Leinweber, P., R. Meissner, K.U. Eckhardt, and J. Seeger. 1999. Management effects on forms of phosphorus in soil and leaching losses. Eur. J. Soil Sci. 50:413–424.
- Maguire, R.O., R.H. Foy, J.S. Bailey, and J.T. Sims. 2001a. Estimation of the phosphorus sorption capacity of acidic soils in Ireland. Eur. J. Soil Sci. 52:479–488.
- Maguire, R.O., and J.T. Sims. 2002. Soil testing to predict phosphorus leaching. J. Environ. Qual. 31:1601–1609.[Abstract/Free Full Text]
- Maguire, R.O., J.T. Sims, and R.H. Foy. 2001b. Long term kinetics for phosphorus sorption-desorption by high phosphorus soils from Ireland and the Delmarva Peninsula, USA. Soil Sci. 166:557–565.
- Maguire, R.O., J.T. Sims, and F.C. Coale. 2000. Phosphorus solubility in biosolids amended farm soils in the mid-Atlantic region of the USA. J. Environ. Qual. 29:1225–1233.[Abstract/Free Full Text]
- McDowell, R.W., and A.N. Sharpley. 2001a. Approximating phosphorus release from soils to surface runoff and subsurface drainage. J. Environ. Qual. 30:508–520.[Abstract/Free Full Text]
- McDowell, R.W., and A.N. Sharpley. 2001b. Phosphorus losses in subsurface flow before and after manure application to intensively farmed land. Sci. Tot. Environ. 278:113–125.
- McKeague, J., and J.H. Day. 1966. Dithionite and oxalate-extractable Fe and Al as aids in differentiating various classes of soils. Can. J. Soil Sci. 46:13–22.
- Mehlich, A. 1984. Mehlich 3 soil test extractant: A modification of Mehlich 2 extractant. Commun. Soil Sci. Plant Anal. 15:1409–1416.
- Murphy, J., and J.P. Riley. 1962. A modified single solution method for the determination of phosphate in natural waters. Anal. Chim. Acta. 27:31–36.
- Pautler, M.C., and J.T. Sims. 2000. Relationships between soil test phosphorus, soluble phosphorus and phosphorus saturation in Delaware soils. Soil Sci. Soc. Am. J. 64:765–773.[Abstract/Free Full Text]
- Pierzynski, G.M., J.T. Sims, and G.F. Vance. 2000. Soils and environmental quality. 2nd ed. CRC Press, Boca Raton, FL.
- SAS Institute. 1998. SAS user's guide: Statistics. Version 8.0 ed. SAS Inst. Cary, NC.
- Schoumans, O.F., and P. Groenendijk. 2000. Modeling soil phosphorus levels and phosphorus leaching from agricultural land in the Netherlands. J. Environ. Qual. 29:111–116.
- Sims, J.T., A.C. Edwards, O.F. Schoumans, and R.R. Simard. 2000. Integrating soil phosphorus testing into environmentally based agricultural management practices. J. Environ. Qual. 29:60–71.
- Sims, J.T., A.B. Leytem, and K.L. Gartley. 2001. Interpreting soil phosphorus tests. NM-04. College of Agric. and Natural Resour., Univ. of Delaware, Newark.
- Sims, J.T., R.O. Maguire, A.B. Leytem, K.L. Gartley, and M.C. Pautler. 2002. Evaluation of Mehlich 3 as an agri-environmental soil phosphorus test for the mid-Atlantic United States. Soil Sci. Soc. Am. J. 66:2016–2032.[Abstract/Free Full Text]
- Sims, J.T., and K.L. Gartley. 1996. Nutrient management handbook for Delaware. Univ. Delaware, Newark, Delaware. Coop. Bull. No. 59.
- Sims, J.T., and S.E. Heckendorn. 1991. Methods of analysis of the University of Delaware soil testing laboratory. Coop. Bull. No. 10. University of Delaware, Newark.
- Sims, J.T., R.R. Simard, and B.C. Joern. 1998. Phosphorus loss in agricultural drainage: Historical perspective and current research. J. Environ. Qual. 27:277–293.[Abstract/Free Full Text]
- Solis, P., and J. Torrent. 1989. Phosphate sorption by calcareous Vertisols and Inceptisols of Spain. Soil Sci. Soc. Am. J. 53:456–459.[Abstract/Free Full Text]
- Turner, B.L., and P.M. Haygarth. 2000. Phosphorus forms and concentrations in leachate under four grassland soil types. Soil Sci. Soc. Am. J. 64:1090–1099.[Abstract/Free Full Text]
- U.S. Environmental Protection Agency. 2000. The quality of our nation's water. A summary of the National Water Quality Inventory: 1998 Report to Congress. EPA841-S-00-001.
- van Riemsdijk, W.H., L.J.M. Boumans, and F.A.M. De Haan. 1984. Phosphate sorption by soils: I. A model for phosphate reaction with metal oxides in soil. Soil Sci. Soc. Am. J. 48:537–541.[Abstract/Free Full Text]
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