Interpretation of a single-point P buffering index for adjusting critical levels of the Colwell soil P test

Soil Research ◽  
2007 ◽  
Vol 45 (1) ◽  
pp. 55 ◽  
Author(s):  
P. W. Moody
Keyword(s):  
Buffer Capacity ◽  
Soil Phosphorus ◽  
Single Point ◽  
Maximum Yield ◽  
P Value ◽  
P Availability ◽  
Soil P ◽  
P Concentration ◽  
Soil P Test ◽  
Rate Of Increase

Soil phosphorus (P) buffer capacity is the change in the quantity of sorbed P required per unit change in solution P concentration. Because P availability to crops is mainly determined by solution P concentration, as P buffer capacity increases, so does the quantity of P required to maintain a solution P concentration that is adequate for crop demand. Bicarbonate-extractable P using the Colwell method is the most common soil P test used in Australia, and Colwell-P can be considered to estimate P quantity. Therefore, as P buffer capacity increases, the Colwell-P concentration required for maximum yield also increases. Data from several published and unpublished studies are used to derive relationships between the ‘critical’ Colwell-P value (Colwell-P at 90% maximum yield) and the single-point P buffer index (PBI) for annual medics, soybean, potato, wheat, and temperate pasture. The rate of increase in critical Colwell-P with increasing PBI increases in the order: temperate pasture < medics < wheat < potato. Indicative critical Colwell-P values are given for the 5 crops at each of the PBI categories used to describe soil P buffer capacity as it increases from extremely low to very high.

Soil phosphorus parameters affecting phosphorus availability to, and fertilizer requirements of, maize (Zea mays)

Soil Research ◽  
1988 ◽  
Vol 26 (4) ◽  
pp. 611 ◽  
Author(s):  
PW Moody ◽  
RL Aitken ◽  
BL Compton ◽  
S Hunt
Keyword(s):  
Zea Mays ◽  
Buffer Capacity ◽  
Single Point ◽  
Maximum Yield ◽  
P Uptake ◽  
Phosphorus Concentration ◽  
P Availability ◽  
Phosphorus Sorption ◽  
Soil P ◽  
Curvature Coefficient

The phosphorus status of each of 26 surface soils from Queensland was characterized by laboratory measurements and a glasshouse experiment. The glasshouse trial investigated the response between applied P in each soil and maize (Zea mays) dry matter yield. In the laboratory, the quantity of soil P was estimated by extraction with 0.5 M NaHCO3 (PB), and the intensity was estimated by soil solution P, 0.005 M CaCl2 extraction and equilibrium phosphorus concentration (EPC). Phosphorus-sorption curves were established for each soil and the data were used to derive the buffering index (BI) and equilibrium buffer capacity (EBC). Four single-point sorption indices were also determined. The desorption buffer capacity (dBC) of each soil was obtained in the laboratory by equilibrating soil samples with anion exchange resin for periods ranging from 0.1 to 18 h. This paper reports the relationships between the various P parameters and (i) the P uptake by maize (Zea mays) grown in untreated soil, and (ii) the amount of added P required for 90% maximum yield. Intensity, as estimated by EPC, was significantly (P < 0.001) correlated with P uptake. Any of the BI, EBC or the single-point sorption indices significantly improved the variation in P uptake accounted for by PB alone, but not to the same level as that obtained with EPC alone. When PB was combined with dBC, more variance was accounted for in P uptake than by using any of the adsorption buffer capacity measurements. The effects of quantity, intensity and buffer capacity on P availability are discussed in terms of their effects on P diffusion. For the suite of soils studied, it is concluded that intensity is the prime factor governing availability, and that the usefulness of adsorption buffer capacity measurements depends on their correlation with desorption buffer capacity. Variation in P requirement was best described by a combination of EPC and the Mitscherlich curvature coefficient, or EPC and one of the single-point sorption indices. As the single-point sorption indices were highly correlated with desorption buffer capacity, adsorption buffer capacity, and the curvature coefficient, they offer a convenient measure of the sorption properties of a soil.

Soil phosphorus tests II: A comparison of soil test–crop response relationships for different soil tests and wheat

2013 ◽  
Vol 64 (5) ◽  
pp. 469 ◽  
Author(s):  
Simon D. Speirs ◽  
Brendan J. Scott ◽  
Philip W. Moody ◽  
Sean D. Mason
Keyword(s):  
Grain Yield ◽  
Confidence Intervals ◽  
Buffer Capacity ◽  
Soil Phosphorus ◽  
Soil Test ◽  
Soil Tests ◽  
P Values ◽  
Soil P ◽  
Soil P Test ◽  
R Value

The performance of a wide range of soil phosphorus (P) testing methods that included established (Colwell-P, Olsen-P, BSES-P, and CaCl2-P) and more recently introduced methods (DGT-P and Mehlich 3-P) was evaluated on 164 archived soil samples corresponding to P fertiliser response experiments with wheat (Triticum aestivum) conducted in south-eastern Australia between 1968 and 2008. Soil test calibration relationships were developed for relative grain yield v. soil test using (i) all soils, (ii) Calcarosols, and (iii) all ‘soils other than Calcarosols’. Colwell-P and DGT-P calibration relationships were also derived for Calcarosols and Vertosols containing measureable CaCO3. The effect of soil P buffer capacity (measured as the single-point P buffer index corrected for Colwell-P, PBICol) on critical Colwell-P values was assessed by segregating field sites based on their PBICol class: very very low (15–35), very low (36–70), low (71–140), and moderate (141–280). All soil P tests, except Mehlich 3-P, showed moderate correlations with relative grain yield (R-value ≥0.43, P < 0.001) and DGT-P exhibited the largest R-value (0.55). Where soil test calibrations were derived for Calcarosols, Colwell-P had the smallest R-value (0.36), whereas DGT-P had an R-value of 0.66. For ‘soils other than Calcarosols’, R-values >0.45 decreased in the order: DGT-P (r = 0.55), Colwell-P (r = 0.49), CaCl2-P (r = 0.48), and BSES-P (r = 0.46). These results support the potential of DGT-P as a predictive soil P test, but indicate that Mehlich 3-P has little predictive use in these soils. Colwell-P had tighter critical confidence intervals than any other soil test for all calibrations except for soils classified as Calcarosols. Critical Colwell-P values, and confidence intervals, for the very very low, very low, and low P buffer capacity categories were within the range of other published data that indicate critical Colwell-P value increases as PBICol increases. Colwell-P is the current benchmark soil P test used in Australia and for the field trials in this study. With the exception of Calcarosols, no alternative soil P testing method was shown to provide a statistically superior prediction of response by wheat. Although having slightly lower R-values (i.e. <0.1 difference) for some calibration relationships, Colwell-P yielded tighter confidence intervals than did any of the other soil tests. The apparent advantage of DGT-P over Colwell-P on soils classified as Calcarosols was not due to the effects of calcium carbonate content of the analysed surface soils.

The systematic effect of soil P buffer capacity on Colwell soil P test v. plant response calibration exists only when field experiments are adjacent

Soil Research ◽  
2004 ◽  
Vol 42 (7) ◽  
pp. 763 ◽  
Author(s):  
M. D. A. Bolland ◽  
R. J. Gilkes
Keyword(s):  
Buffer Capacity ◽  
Field Experiments ◽  
Soil Phosphorus ◽  
Triticum Aestivum L ◽  
Systematic Effect ◽  
Calibration Data ◽  
P Values ◽  
Soil P ◽  
Soil P Test ◽  
The Relationship

Thirteen field experiments distributed throughout south-western Australia examined the relationship between percentage of maximum grain yield of wheat (Triticum aestivum L. cv. Aroona) and Colwell soil phosphorus (P) values. These calibration data were fitted to a linear equation, and the slope values for the 13 sites were compared with the P buffer capacity (PBC) of the soils. There was no systematic relationship between these variables except for 3 adjacent sites at Badgingarra and for 3 adjacent sites at Newdegate. We conclude that differences in climate and site conditions have a greater effect than PBC on Colwell soil P test calibration when widely separated sites are compared.

An appraisal of soil phosphorus testing data for crops and pastures in South Australia

1995 ◽  
Vol 35 (7) ◽  
pp. 979 ◽  
Author(s):  
DJ Reuter ◽  
CB Dyson ◽  
DE Elliott ◽  
DC Lewis ◽  
CL Rudd
Keyword(s):  
Soil Properties ◽  
Soil Phosphorus ◽  
South Australia ◽  
Soil Types ◽  
Soil P ◽  
P Concentration ◽  
Soil P Test ◽  
Wide Range ◽  
The Relationship ◽  
Proportional Yield

Data from more than 580 field experiments conducted in South Australia over the past 30 years have been re-examined to estimate extractable soil phosphorus (P) levels related to 90% maximum yield (C90) for 7 crop species (wheat, barley, oilseed rape, sunflower, field peas, faba beans, potato) and 3 types of legume-based pasture (subterranean clover, strawberry clover, annual medics). Data from both single-year and longer term experiments were evaluated. The C90 value for each species was derived from the relationship between proportional yield responsiveness to applied P fertiliser rates (determined as grain yield in crops and herbage yield in ungrazed pastures) and extractable P concentrations in surface soils sampled before sowing. Most data assessments involved the Colwell soil P test and soils sampled in autumn to 10 cm depth. When all data for a species were considered together, the relationship between proportional yield response to applied P and soil P status was typically variable, particularly where Colwell soil P concentration was around C90. When data could be grouped according to common soil types, soil surface texture, or P sorption indices (selected sites), better relationships were discerned. From such segregated data sets, different C90 estimates were derived for either different soil types or soil properties. We recommend that site descriptors associated with the supply of soil P to plant roots be determined as a matter of course in future P fertiliser experiments in South Australia. Given the above, we also contend that the Colwell soil P test is reasonably robust for estimating P fertiliser requirements for the diverse range of soils in the agricultural regions of the State. In medium- and longer term experiments, changes in Colwell soil P concentration were measured in the absence or presence of newly applied P fertiliser. The rate of change (mg soil P/kg per kg applied P/ha) appeared to vary with soil type (or soil properties) and, perhaps, cropping frequency. Relatively minor changes in soil P status were observed due to different tillage practices. In developing P fertiliser budgets, we conclude that a major knowledge gap exists for estimating the residual effectiveness of P fertiliser applied to diverse soil types under a wide range of South Australian farming systems.

Soil phosphorus buffering measures should not be adjusted for current phosphorus fertility

Soil Research ◽  
2008 ◽  
Vol 46 (8) ◽  
pp. 676 ◽  
Author(s):  
L. L. Burkitt ◽  
P. W. G. Sale ◽  
C. J. P. Gourley
Keyword(s):  
Agricultural Soils ◽  
Soil Phosphorus ◽  
Single Point ◽  
Sorption Isotherms ◽  
Phosphorus Sorption ◽  
Soil P ◽  
P Sorption ◽  
P Concentration ◽  
Extractable P ◽  
Fertiliser Application

Soil phosphorus (P) sorption is an important and relatively stable soil property which dictates the equilibrium between sorbed and solution P. Soil P sorption measures are commonly adjusted for the effect of current P fertility on the amount of P a soil sorbs. In the case of highly fertilised agricultural soils, however, this adjustment is likely to be inappropriate as it may mask changes in a soil’s capacity to sorb P, which could affect future P fertiliser applications. A study was undertaken to compare adjusted or unadjusted methods of measuring P sorption using 9 pasture soils sampled from southern Victoria which had previously received P fertiliser and lime. The P sorption assessment methods included: P sorption isotherms, P-buffering capacity (PBC) measures (slope between equilibrium P concentration of 0.25 and 0.35 mg P/L), and single-point P-buffering indices (PBI), with methods either adjusted or unadjusted for current P fertility. A single application of 280 kg P/ha, 6 months before sampling, resulted in a general negative displacement of unadjusted P sorption isotherm curves, indicating reduced P sorption on 8 of the 9 soils. Adding the Colwell extractable P concentration to the amount of P sorbed before calculating the slope (PBC+ColP), tended to negate this fertiliser effect and, in 2 of the 9 soils, resulted in a significant increase in PBC+ColP values. Increasing rates of P fertiliser application (up to 280 kg P/ha) resulted in a consistent trend to decreasing PBI values (unadjusted for Colwell P), which was significant at 4 of the 9 sites after 6 months. However, only minimal changes in PBI values were determined when PBI was adjusted for current P fertility (PBI+ColP). Phosphorus sorption properties appeared reasonably stable over time, although 2 soils, both Ferrosols, indicated significant linear increases in PBI values when these sites remained unfertilised for 30 months. Lime significantly increased both PBI and PBI+ColP values at all sites 6 months after application, but the effect generally diminished after 30 months, suggesting PBI measurements should not be taken immediately after liming. These results demonstrate that unadjusted measures of P sorption are more likely to accurately reflect changes in soil P sorption capacity following P fertiliser applications and suggest that the unadjusted PBI be used in commercial soil testing rather that the currently adjusted PBI+ColP.

Improved Plant Diversity as a Strategy to Increase Available Soil Phosphorus

2019 ◽  
Vol 103 (1) ◽  
pp. 43-45 ◽  
Author(s):  
Carlos Crusciol ◽  
João Rigon ◽  
Juliano Calonego ◽  
Rogério Soratto
Keyword(s):  
Crop Yields ◽  
Soil Phosphorus ◽  
Cropping System ◽  
P Availability ◽  
P Fractions ◽  
Crop Species ◽  
Soil P ◽  
Residue Decomposition ◽  
Available Soil Phosphorus ◽  
Crop Residue Decomposition

Some crop species could be used inside a cropping system as part of a strategy to increase soil P availability due to their capacity to recycle P and shift the equilibrium between soil P fractions to benefit the main crop. The release of P by crop residue decomposition, and mobilization and uptake of otherwise recalcitrant P are important mechanisms capable of increasing P availability and crop yields.

scholarly journals Soil phosphorus bioavailability as influenced by long-term management and applied phosphorus source

2019 ◽  
Vol 99 (3) ◽  
pp. 292-304
Author(s):  
Tandra D. Fraser ◽  
Derek H. Lynch ◽  
Ivan P. O’Halloran ◽  
R. Paul Voroney ◽  
Martin H. Entz ◽  
...  
Keyword(s):  
Management Practices ◽  
Soil Phosphorus ◽  
P Uptake ◽  
Italian Ryegrass ◽  
P Availability ◽  
P Fractionation ◽  
Soil P ◽  
Plant P Uptake ◽  
Term Management

Soil phosphorus (P) availability may be impacted by management practices, thereby affecting plant P uptake and plant response to P amendments. The aim of this study was to determine the effects of long-term management on soil P pools and to assess the response of P bioavailability, plant growth, and P uptake to mineral versus manure P treatments. Soils were collected from plots under organic (ORG), organic with composted manure (ORG + M), conventional (CONV), and restored prairie (PRA) management. Italian ryegrass (Lolium multiflorum L.) seedlings were grown in the greenhouse for 106 d in soils amended with various rates of manure or mineral P. The ORG soil had lower concentrations of labile P (resin-P and NaHCO3-P) compared with the CONV and PRA soils, as determined by sequential P fractionation prior to planting. Ryegrass biomass (root + shoot) and shoot P uptake from soils receiving no P were significantly lower for the ORG than all other management systems. Although apparent P use efficiency of the whole plant was increased by low P rate in the ORG management system, the source of applied P, manure > mineral, only influenced Olsen test P.

Response by sugar beet to superphosphate, particularly in relation to soils containing little available phosphorus

1976 ◽  
Vol 86 (1) ◽  
pp. 181-187 ◽  
Author(s):  
A. P. Draycott ◽  
M. J. Durrant
Keyword(s):  
Sugar Beet ◽  
Soil Phosphorus ◽  
Maximum Yield ◽  
P Uptake ◽  
Available Phosphorus ◽  
Triple Superphosphate ◽  
Phosphorus Fertilizer ◽  
Average Yield ◽  
Soil P ◽  
The Cost

SUMMARYTwenty experiments between 1970 and 1974 tested the effect of five amounts of triple superphosphate (0–110 kg P/ha) on sugar-beet yield in fields where soil contained little sodium bicarbonate-soluble phosphorus. The average yield without phosphorus fertilizer was 6·69 t/ha sugar and the increase from the optimum dressing 0·46 t/ha; the average soil concentration was 12 mg P/l. The fertilizer increased yield by 0·77 t/ha sugar on fields with 0–9 mg/l soil phosphorus, by 0·31 t/ha when soil phosphorus was 10–15 mg/l and had little effect on soils containing larger amounts.The concentration of phosphorus in plants harvested in mid-summer contained on average 0·29% P in dried tops and 0·13% in roots when given no phosphorus fertilizer, representing a total of 19·3 kg/ha P uptake. Giving superphosphate increased the phosphorus in both dried tops and roots by up to 0·03% and there was 3·7 and 1·7 kg/ha more phosphorus in tops and roots respectively. On the most responsive fields (0–9 mg/l soil P), the fertilizer increased the phosphorus in tops and roots by 0·05% and total uptake by 7 kg P/ha. The increase in uptake (or recovery) of fertilizer varied from 15% when 14 kg P/ha was given to less than 5% when 110 kg P/ha was used.A dressing of 27 kg P/ha was adequate for maximum yield on 19 of the 20 fields. When fields were grouped, 0–9, 10–15, 16–25 and > 26 mg/l NaHCO3-soluble soil phosphorus, and taking into account the value of the increased sugar yield, the cost of the fertilizer and its residual value, 60, 30, 20 and 10 kg P/ha respectively were the most profitable dressings. These experiments provide evidence, however, that the fertilizer would be used more efficiently if fields containing 0–9 mg soil phosphorus were subdivided into those with 0–4·5 and those with 4·6–9·0 mg/l and the groups given 80 and 40 kg P/ha respectively. These recommendations are substantially less than those used at present; they are adequate for sugar beet but other crops in the rotation would need similar close examination to ensure maximum yield and maintain adequate soil reserves of phosphorus.

Effect of lime stabilisation of enhanced biological phosphorus removal sludges on the phosphorus availability to plants

2003 ◽  
Vol 48 (1) ◽  
pp. 155-162 ◽  
Author(s):  
D. Seyhan ◽  
A. Erdincler
Keyword(s):  
Phosphorus Removal ◽  
Maximum Yield ◽  
P Availability ◽  
Alkaline Soil ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Soil P ◽  
Pot Experiments ◽  
Application Rates ◽  
Biological Phosphorus

This study investigates the phosphorus (P) availability in lime stabilised biological phosphorus removal sludges. Lime-stabilised sludge amendments (LS), non-stabilised sludge amendments (S) and amendments with a chemical fertiliser (TSP) were compared through plant uptake of P and Olsen-extractable P for this purpose. In the first part of the study, pot experiments were performed, where a dewatered biological phosphorus removal sludge was applied to pots at increasing rates of P. A P-deficient, alkaline soil was used in the experiments and Lollium perenne was the testing plant. In the second part (incubation tests), the waste activated sludge from an Enhanced Biological Phosphorus Removal (EBPR) process was mixed with the same soil at a pre-determined P-based rate. The pot experiments showed that, the efficiency of the fertilising materials, based on the minimum P applied to reach the maximum yield, was in the following order: S∼LS&gt;TSP. However, the P concentration in the plant tissue was in the order of TSP&gt;S&gt;LS for all P application rates. In the incubation tests, the EBPR sludge raised the soil P-level from the low range to the medium range. The P-availability in TSP decreased rapidly with time whereas that in S and LS remained almost constant.

Responses of herbage yield and soil phosphorus fractions to phosphorus fertilisation on a degraded arid steppe

2018 ◽  
Vol 69 (8) ◽  
pp. 846 ◽  
Author(s):  
Dangjun Wang ◽  
Zhibin He ◽  
Zhen Zhang ◽  
Qingfeng Du ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Soil Phosphorus ◽  
Pot Experiment ◽  
Available Phosphorus ◽  
P Availability ◽  
Organic P ◽  
Soil P ◽  
Sheep Manure ◽  
Arid Steppe ◽  
Plant Yields ◽  
Phosphorus Fertilisation

Low plant-available phosphorus (P) in degraded arid steppes greatly limits plant yields. However, whether exterior P addition will improve the soil P availability and thus increase plant yield in these degraded arid steppes is still not certain. In the current study, a severely degraded arid steppe in Inner Mongolia, China, with soil-available P <5 mg/kg, was fertilised annually with chemical or manure P for two years (2014, dry year; 2015, wet year). There were six fertilisation treatments: 0, 30 kg P/ha, 60 kg P/ha, 90 kg P/ha, 4000 kg sheep manure/ha (equalling 16.4 kg P/ha) and 8000 kg sheep manure/ha (32.8 kg P/ha). A pot experiment with Stipa krylovii (the dominant plant species in the tested steppe) and five P application rates (0, 30, 60, 90 and 120 kg P/ha) was also conducted, under well-watered and nitrogen-fertilised conditions, using surface soils from unfertilised plots in the field. Results indicated that the tested soils had strong P adsorption capacity and weaker desorption capacity, and that the labile P fractions were quickly transformed into less labile fractions, reducing P availabilities. Overall, chemical P fertiliser resulted in the accumulation of Ca10-P and occluded P, whereas sheep manure resulted in the accumulation of moderately resistant organic P and highly resistant organic P. Phosphorus fertilisation was associated with an increase in plant P concentrations in both 2014 and 2015, and a low P rate (30 kg P/ha in the current study) was able to improve the aboveground biomass in both the field experiment in the wet year and the pot experiment under well-watered conditions. Thus, in degraded arid steppes, P fertilisation may be unnecessary in dry years. A low rate of P fertilisation is recommended in wet years to improve soil P status and steppe plant productivity.

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