Soil testing for phosphorus: comparing the Mehlich 3 and Colwell procedures for soils of south-western Australia

Soil Research ◽  
2003 ◽  
Vol 41 (6) ◽  
pp. 1185 ◽  
Author(s):  
M. D. A. Bolland ◽  
D. G. Allen ◽  
K. S. Walton

Soil samples were collected from 14 long-term field experiments in south-western Australia to which several amounts of superphosphate or phosphate rock had been applied in a previous year. The samples were analysed for phosphorus (P) by the Colwell sodium bicarbonate procedure, presently used in Western Australia, and the Mehlich 3 procedure, being assessed as a new multi-element test for the region. For the Mehlich procedure, the concentration of total and inorganic P in the extract solution was measured. The soil test values were related to yields of crops and pasture measured later on in the year in which the soil samples were collected.The Mehlich 3 procedures (Mehlich 3 total and Mehlich 3 inorganic soil test P values) were similar, with the total values mostly being slightly larger. For soil treated with superphosphate, for each year of each experiment: (i) Mehlich 3 values were closely correlated with Colwell values; and (ii) the relationship between plant yield and soil test P (the soil P test calibration) was similar for the Colwell and Mehlich 3 procedures. However, for soil treated with phosphate rock, the Colwell procedure consistently produced lower soil test P values than the Mehlich 3 procedure, and the calibration relating plant yield to soil test P was different for the Colwell and Mehlich 3 procedures, indicating, for soils treated with phosphate rock, separate calibrations are required for the 2 procedures. We conclude that for soils of south-western Australia treated with superphosphate (most of the soils), the Mehlich 3 procedure can be used instead of the Colwell procedure to measure soil test P, providing support for the Mehlich 3 procedure to be developed as the multi-element soil test for the region.


Soil Research ◽  
2010 ◽  
Vol 48 (8) ◽  
pp. 682 ◽  
Author(s):  
M. D. A. Bolland ◽  
W. K. Russell

Soil testing was conducted during 1999–2009 to determine lime and fertiliser phosphorus (P), potassium (K), and sulfur (S) requirements of intensively grazed, rain-fed, ryegrass dairy pastures in 48 paddocks on sand to sandy loam soils in the Mediterranean-type climate of south-western Australia. The study demonstrated that tissue testing was required in conjunction with soil testing to confirm decisions based on soil testing, and to assess management decisions for elements not covered by soil testing. Soil testing for pH was reliable for indicating paddocks requiring lime to ameliorate soil acidity, and to monitor progress of liming. Soil P testing proved reliable for indicating when P fertiliser applications were required, with no P being required when soil-test P was above the critical value for that soil, and when no P was applied, tissue testing indicated that P remained adequate for ryegrass production. Soil testing could not be used to determine paddocks requiring fertiliser K and S, because both elements can leach below the root-zone, with rainfall determining the extent of leaching and magnitude of the decrease in pasture production resulting from deficiency, which cannot be predicted. The solution is to apply fertiliser K and S each year, and use tissue testing to improve fertiliser K and S management. Research has shown that, for dairy and other grazing industries in the region, laboratories need measure and report every year soil pH and soil-test P only, together with measuring every 3–5 years the P-buffering index (estimating P sorption of soil), organic carbon content, and electrical conductivity.



2018 ◽  
Vol 102 (4) ◽  
pp. 11-13
Author(s):  
Florencia Sucunza ◽  
Flavio Gutiérrez Boem ◽  
Fernando García ◽  
Miguel Boxler ◽  
Gerardo Rubio

Data from long-term crop rotation study sites were combined to evaluate the effect of long-term application (and omission) of P fertilizers. The impact of maintaining either a negative or positive P balances on soil test P at five distinct sites was described by single response functions despite a range of differences in soil properties.



2008 ◽  
Vol 13 (3) ◽  
pp. 276 ◽  
Author(s):  
I. SAARELA ◽  
A. JÄRVI ◽  
H. HAKKOLA

Fertilising with phosphorus (P) ensures continuous supply of an essential growth factor as necessary for productive and sustainable agriculture. The amounts of P required to attain and maintain an adequate P status in the soil were investigated in field experiments at 22 sites in Finland on soils containing large amounts of residual fertiliser P. The effects of five rates (0, 15, 30, 45 and 60 kg ha-1) of annual P application were measured in the soil by chemical methods after 9 to 15 experimental years, and the changes in soil test P values (STP) were compared with P balances. Stratification of P in ley soil by broadcast application of fertilisers was assessed at four sites. The mean changes of STP in the whole topsoil caused by P fertilisation expressed as per cent of the balance difference were 3.5% (0.0159 mg dm-3)/(kg ha-1) in the acid ammonium acetate test (PAc), 4.7% (0.0214 mg dm-3)/(kg ha-1) in water extraction (Pw) and 9.7% (0.058 mg kg-1)/(kg ha-1) in sodium bicarbonate extraction (modified Olsen P). Initially high PAc values tended to slowly decrease at zero P balance, while low values did not change without some particular reason, such as soil acidification or mixing of the topsoil with some of the less fertile subsurface soil. A thin layer of the uppermost soil was quickly enriched by broadcast application of P fertiliser.;



2006 ◽  
Vol 46 (8) ◽  
pp. 1051 ◽  
Author(s):  
M. D. A. Bolland ◽  
R. F. Brennan

Plant testing of wheat crops in south-western Australia, sown using no-till for >7 years, often indicates marginal to deficient levels of the soil immobile elements phosphorus (P), copper (Cu) and zinc (Zn). In this region, P, Cu and Zn fertilisers are usually placed (drilled) with the seed while sowing crops. However, in no-till cropping, because the fertilisers are placed in the same rows as the seed during sowing, in the years after application the 3 elements are no longer mixed through the top 10 cm of soil. It may be more effective to deep band fertiliser below seed while sowing no-till crops. Alternatively, cultivating the top 10 cm of soil every 5–7 years would mix previously applied fertiliser P, Cu and Zn through the topsoil, which should improve the effectiveness of the fertiliser residues for the current and subsequent no-till crops. In field experiments in paddocks in south-western Australia sown using no-till for 7–11 years, we compared these 2 alternative methods to the standard no-till practice of drilling fertiliser with the seed in the same crop rows. No shoot or grain yield responses of wheat were obtained. The exception was that in 1 experiment cultivating the topsoil before drilling P with seed was more effective than drilling or deep banding P. Concentrations of P, Cu and Zn measured in wheat shoots or grain were either unaffected by treatment, or, compared with drilling fertiliser with seed, were larger for the other 2 methods, indicating these 2 methods were more effective at increasing the concentrations of the elements in plant parts. The 3 elements have been shown to have good residual values for crop production in the region. Therefore, we recommend that experiments should not be performed in existing no-till paddocks until the residual value of P, Cu and Zn applied in the old cropping system has become negligible, which could, for Cu and Zn in particular, take many years. In the second year, the experiments were used to compare 4 different ways of collecting soil samples from the top 10 cm of soil (standard soil sampling depth used in south-western Australia) to measure soil test P (Colwell), Cu (ammonium oxalate) and Zn (DTPA). The samples were either collected randomly within the plots (present method), always in the rows used to sow seed and apply fertiliser, always between the rows, or half in and half between the rows. Soil test values for P, Cu and Zn were unaffected by amount of element applied and method of application when samples were collected between rows, at random, or from all banded treatments where fertiliser was placed below the 0–10 cm sampling depth. Soil test values for samples collected in rows increased as the amount of fertiliser applied increased and were about double the values for samples collected half in and half between rows.



HortScience ◽  
2019 ◽  
Vol 54 (7) ◽  
pp. 1237-1242 ◽  
Author(s):  
Michael F. Polozola ◽  
Daniel E. Wells ◽  
J. Raymond Kessler ◽  
Wheeler G. Foshee ◽  
Amy N. Wright ◽  
...  

An experiment was conducted to determine the effects of banded phosphorus (P) applications at differing rates in irrigated and nonirrigated pecan (Carya illinoinensis) plots on P movement within the soil, P uptake and movement within pecan trees, and the yield and quality of nuts. On 20 Mar. 2015, P applications of 0 kg·ha−1 (0×), 19.6 kg·ha−1 (1×), 39.2 kg·ha−1 (2×), and 78.5 kg·ha−1 (4×) were administered to bands of triple superphosphate to randomly selected trees in nonirrigated and irrigated plots of a ‘Desirable’ orchard bordered by ‘Elliot’ trees. When P was applied at the 2× and 4× rates, the total soil test P decreased linearly by 35% and 54%, respectively, in nonirrigated plots and by 41% and 59%, respectively, in irrigated plots over the course of the experiment. There was no change in soil test P over time at the 0× rate for either irrigation regimen; however, at the 1× rate, soil test P decreased 44% in the irrigated plot but did not change in the nonirrigated plot. The largest linear decrease of the soil test P from the start of the experiment to the end of the experiment occurred in the top 0 to 7.6 cm. In contrast, soil test P at a depth of 15.2 to 22.9 cm decreased linearly by 23% in the nonirrigated plot, but it did not decrease over time in the irrigated plot. Increasing the P application rate increased foliar P quadratically in the nonirrigated plot, but only the 4× application rate increased foliar P compared with the 0× control. In the irrigated plot, foliar P concentrations decreased linearly from 2015 to 2017, and foliar P concentrations were not influenced by the P application rate. No differences in pecan yield or quality were observed in either irrigated or nonirrigated plots. Overall, P banding may not be the most sustainable way to increase foliar concentrations of P quickly or to maintain concentrations of the nutrient in the long term.



2003 ◽  
Vol 12 (2) ◽  
pp. 117-132 ◽  
Author(s):  
I. SAARELA ◽  
A. JÄRVI ◽  
H. HAKKOLA

The native reserves of phosphorus (P) in Finnish soils are sizeable but poorly available to plants. The P status has been generally poor, but large rates of P applied since the 1940s have substantially enhanced the supply of P from the soil. As a means of optimising P fertilisation of crops grown in the improved soils and promoting agro-environmental sustainability of agriculture, long-term field experiments were established in 1977-1981 on various soil types around Finland, between the latitudes of 60 and 65 N. The experimental sites (8 Cambisols, 9 Regosols, 6 Histosols, 1 Podsol) were moderately acidic (pH w 5.6, range 4.6-6.6) and contained 1.6-31.2% organic C, and (mineral soils) 3-74% clay. The concentration of total P was 1.22 (0.66-1.87) g kg -1 , and the inorganic fraction separated with fluoride and hydroxide extractions (Al,Fe-P) was 8.2% (4.5-12.4%) of oxalate extractable Al+Fe (P saturation index). In mineral topsoil the pool of Al,Fe-P was 850 kg ha -1 , which is 300 kg ha -1 larger than was obtained in the early 1960s and 600 kg ha -1 larger than found in virgin soils. The soil test P value was 13.1 (3.7-60) mg dm -3 by the acid ammonium acetate method, 11.5 (1.6-42) mg dm -3 by a water extraction method (1:60 v/v) and 61 (23-131) mg kg -1 with a modified Olsen method. The intensity factor of soil P status has remained at a relatively low level in a major part of the cultivated area.;



Soil Research ◽  
2003 ◽  
Vol 41 (7) ◽  
pp. 1369 ◽  
Author(s):  
M. D. A. Bolland ◽  
D. G. Allen

Soil samples collected from 8 field experiments in Western Australia to which 5–8 amounts of superphosphate had been applied once only 13–23 years previously were used to measure the phosphorus (P) buffer capacity of soil (PBC) and P sorption by several single-point indices. PBC was estimated from well-defined P sorption curves when several levels of P were added to soil suspensions, and was the amount of P sorbed when the concentration of P in the final solution was raised from 0.25 to 0.35 mg P/L. The single-point P sorption indices were measured by adding one amount of P (10 mg P/L) to soil suspensions (1 : 20, soil : 0.02 M KCl or 0.01 M CaCl2). Three indices were calculated from the amount of P sorbed by soil (S, mg P/kg soil) and the amount of P in solution (c, mg P/L)—(1) the phosphorus retention index (PRI, S/c [L/kg]), (2) the Freundlich retention index (FRI, S/c0.35 [dimensionless]), and (3) the phosphorus sorption index (PSI, S/log10 [c × 1000] [dimensionless])—to provide PRI K & Ca, FRI K & Ca, and PSI K & Ca values. P sorption was also measured by the P buffer index (PBI), the new single-point P sorption index recommended for national use, to provide PBICa values. To estimate the previous P sorbed by soil (native soil P is negligible for these soils, so previously sorbed P originates from fertiliser P applied in a previous year), the amount of P extracted by 0.5 M sodium bicarbonate from soil (Colwell soil test P) was added to the amount of P sorbed by soil to calculate PRI*K & Ca, FRI*K & Ca, PSI*K & Ca, and PBI*Ca values. In addition, previously sorbed P was estimated using the q coefficient of the Freundlich equation; q was added to P sorption to calculate PSI**, FRI**, PSI** and PBI** values to take account of previously sorbed P.For the 8 experiments, PBC values significantly decreased where more fertiliser P had been applied to the soils 13–23 years previously. This indicated that the capacity of the 8 soils to sorb P decreased as more P was applied in a previous year, and a single-point P sorption index would need to reflect this decrease. As the amount of P applied to soil in the field plots increased, the following trends occurred : (1) Colwell soil test P always increased; (2) PRIK & Ca, FRIK & Ca, PSIK & Ca, and PBICa consistently decreased; (3) PRI*K & Ca, FRI*K & Ca, PSI*K & Ca, and PBI*Ca mostly increased, but with some values being unaffected or decreasing; (4) PRI**, FRI**, PSI**, and PBI** values were largely unaffected by the amount of P applied in a previous year. Evidently, either adding Colwell soil test P or q to P sorption to calculate the single-point P sorption indices mostly overestimated P sorption by the sandy, low P sorbing soils used, but the overestimate was larger for Colwell soil test P than for q.



2007 ◽  
Vol 87 (1) ◽  
pp. 73-83 ◽  
Author(s):  
D. Kimaragamage ◽  
O O Akinremi ◽  
D. Flaten ◽  
J. Heard

Quantitative relationships between soil test phosphorus (STP) methods are needed to guide P management especially in manured soils with high P. Our objectives were: (i) to compare amounts of P extracted by different methods; (ii) to develop and verify regression equations to convert results among methods; and (iii) to establish environmental P thresholds for different methods, in manured and non-manured soils of Manitoba. We analyzed 214 surface soil samples (0–15 cm), of which 51 had previous manure application. Agronomic STP methods were Olsen (O-P), Mehlich-3 (M3-P), Kelowna-1 (original; K1-P), Kelowna-2 (modified; K2-P), Kelowna-3 (modified; K3-P), Bray-1 (B1-P) and Miller and Axley (MA-P), while environmental STP methods were water extractable (W-P), Ca Cl2 extractable (Ca-P) and iron oxide impregnated filter paper (FeO-P) methods. The different methods extracted different amounts of P, but were linearly correlated. For an O-P range of 0–30 mg kg-1, relationships between O-P and other STP were similar for manured and nonmanured soils, but the relationships diverged at higher O-P levels, indicating that one STP cannot be reliably converted to another using a single equation for manured and non-manured soils at environmentally critical P levels (0–100 mg kg-1 O-P). Suggested environmental soil P threshold ranges, in mg P kg-1, were 88–118 for O-P, 138–184 for K1-P, 108–143 for K2-P, 103–137 for K3-P, 96–128 for B1-P, 84–111 for MA-P, 15–20 for W-P, 5–8 for Ca-P and 85–111 for FeO-P. Key words: Phosphorus, soil test phosphorus, manured soils, non-manured soils, environmental threshold



2018 ◽  
Vol 218 ◽  
pp. 158-170 ◽  
Author(s):  
Theresa Zicker ◽  
Sabine von Tucher ◽  
Mareike Kavka ◽  
Bettina Eichler-Löbermann


2002 ◽  
Vol 42 (2) ◽  
pp. 149 ◽  
Author(s):  
M. D. A. Bolland ◽  
W. J. Cox ◽  
B. J. Codling

Dairy and beef pastures in the high (>800 mm annual average) rainfall areas of south-western Australia, based on subterranean clover (Trifolium subterraneum) and annual ryegrass (Lolium rigidum), grow on acidic to neutral deep (>40 cm) sands, up to 40 cm sand over loam or clay, or where loam or clay occur at the surface. Potassium deficiency is common, particularly for the sandy soils, requiring regular applications of fertiliser potassium for profitable pasture production. A large study was undertaken to assess 6 soil-test procedures, and tissue testing of dried herbage, as predictors of when fertiliser potassium was required for these pastures. The 100 field experiments, each conducted for 1 year, measured dried-herbage production separately for clover and ryegrass in response to applied fertiliser potassium (potassium chloride). Significant (P<0.05) increases in yield to applied potassium (yield response) were obtained in 42 experiments for clover and 6 experiments for ryegrass, indicating that grass roots were more able to access potassium from the soil than clover roots. When percentage of the maximum (relative) yield was related to soil-test potassium values for the top 10 cm of soil, the best relationships were obtained for the exchangeable (1 mol/L NH4Cl) and Colwell (0.5 mol/L NaHCO3-extracted) soil-test procedures for potassium. Both procedures accounted for about 42% of the variation for clover, 15% for ryegrass, and 32% for clover + grass. The Colwell procedure for the top 10 cm of soil is now the standard soil-test method for potassium used in Western Australia. No increases in clover yields to applied potassium were obtained for Colwell potassium at >100 mg/kg soil. There was always a clover-yield increase to applied potassium for Colwell potassium at <30 mg/kg soil. Corresponding potassium concentrations for ryegrass were >50 and <30 mg/kg soil. At potassium concentrations 30–100 mg/kg soil for clover and 30–50 mg/kg soil for ryegrass, the Colwell procedure did not reliably predict yield response, because from nil to large yield responses to applied potassium occurred. The Colwell procedure appears to extract the most labile potassium in the soil, including soluble potassium in soil solution and potassium balancing negative charge sites on soil constituents. In some soils, Colwell potassium was low indicating deficiency, yet plant roots may have accessed potassum deeper in the soil profile. Where the Colwell procedure does not reliably predict soil potassium status, tissue testing may help. The relationship between relative yield and tissue-test potassium varied markedly for different harvests in each year of the experiments, and for different experiments. For clover, the concentration of potassium in dried herbage that was related to 90% of the maximum, potassium non-limiting yield (critical potassium) was at the concentration of about 15 g/kg dried herbage for plants up to 8 weeks old, and at <10 g/kg dried herbage for plants older than 10–12 weeks. For ryegrass, there were insufficient data to provide reliable estimates of critical potassium.



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