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

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.


2013 ◽  
Vol 64 (5) ◽  
pp. 469 ◽  
Author(s):  
Simon D. Speirs ◽  
Brendan J. Scott ◽  
Philip W. Moody ◽  
Sean D. Mason

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.



Soil Research ◽  
2007 ◽  
Vol 45 (1) ◽  
pp. 55 ◽  
Author(s):  
P. W. Moody

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.



1995 ◽  
Vol 35 (7) ◽  
pp. 979 ◽  
Author(s):  
DJ Reuter ◽  
CB Dyson ◽  
DE Elliott ◽  
DC Lewis ◽  
CL Rudd

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.



1999 ◽  
Vol 79 (1) ◽  
pp. 71-83 ◽  
Author(s):  
W. J. Bullied ◽  
M. H. Entz ◽  
S. R. Smith Jr.

Crop rotations involving perennial alfalfa (Medicago sativa L.) present the unique problem of terminating the alfalfa stand. Intensive tillage currently used to terminate alfalfa increases the risk of soil erosion and reduces many of the rotational benefits from alfalfa. Inadequate alfalfa termination results in severe competition to the following crop by surviving alfalfa plants. Field experiments were conducted in Manitoba between 1991 and 1993 with the following objectives: 1) to investigate no-till vs. tillage management systems for successful alfalfa termination, 2) to compare fall vs. spring alfalfa termination, 3) to compare the performance of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) seeded into alfalfa residue, and 4) to determine the relationship between alfalfa escapes and grain yield. Fall termination produced higher grain yields than spring termination, however this advantage was only achieved with the better termination treatments capable of lowering alfalfa regrowth below a critical level. The best herbicide treatment tested here was glyphosate at 1.78 kg a.i. ha−1. Successful treatments would have to reduce residual alfalfa basal crown area (a measure of alfalfa regrowth potential) after cereal grain harvest to below 2%. Alfalfa escapes reduced yield of following wheat and barley crops similarly (P > 0.05). When alfalfa termination treatment method allowed some regrowth, in-crop herbicide treatments significantly reduced alfalfa basal crown area. Results of this study indicate that it is feasible to terminate alfalfa with herbicides in the absence of tillage, however an overall cropping strategy, including adequate consideration of weeds present in alfalfa fields at time of termination, must be considered. Key words: Herbicides, competition, recropping, no-till, alfalfa regrowth, soil conservation, sustainable cropping



2002 ◽  
Vol 51 (1-2) ◽  
pp. 167-176 ◽  
Author(s):  
Marianna Magyar ◽  
P. Csathó ◽  
K. Debreczeni ◽  

Five soil P-test methods were compared on the soils of the network of unified Hungarian P fertilization long-term field trials. The effect of P application on the soil P-test values was significant on the different P levels and sites. The average effect of the sites varied between 1.5-fold (H 2 O method) and 3.7- fold (AL-method). The amounts of extracted P increased in the order of H 2 O-P < Olsen-P < Pi-P < AERM-P < AL-P < Corrected AL-P. For studying the relationships between the P values extracted by the different methods, acidic, calcareous and all soils groups were taken into account as a basis. A good correlation was found between the Pi- and AERM-methods in each soil group. Within the acidic soil group, pH has a much less expressed effect on AL-P values, presumably this was the reason why the strongest correlation in this soil group was found between the AL- and the Corr. AL-P methods  The next step in our research will be to calibrate these soil-P tests with plant P uptake and yield responses.



2013 ◽  
Vol 22 (2) ◽  
pp. 139
Author(s):  
L Izhar ◽  
A D Susila ◽  
B S Puswoko ◽  
A Sutandi ◽  
I W Mangku

ABSTRAK.  Fosfor merupakan salah satu hara penting tanah dan aplikasi hara tersebut pada konsentrasi yang sesuai sangat berpengaruh terhadap pertumbuhan tomat. Penelitian tentang studi analisis fosfor tanah dan aplikasi pupuk fosfor pada budidaya tomat pada tanah Inceptisols dilakukan di Kebun Percobaan dan Rumah Kaca di Cikabayan, Institut Pertanian Bogor, dari bulan Maret sampai dengan November 2010. Tujuan penelitian ialah untuk mendapatkan  metode  ekstraksi  fosfor tanah yang terbaik guna menentukan dosis pupuk fosfor pada budidaya tomat  pada tanah Inceptisols. Penelitian menggunakan rancangan acak kelompok dengan perlakuan pemberian pupuk fosfor pada beberapa tingkat dosis yaitu  0X, ¼ X, ½ X, ¾ X, dan 1X, di mana nilai X ialah 368,5 kg/ha P2O5 dengan empat ulangan. Perlakuan pemupukan fosfor diterapkan pada 6 bulan sebelum penanaman tomat. Analisis korelasi dilakukan antara kandungan P tanah dan pertumbuhan tanaman yang ditanam di dalam rumah kaca menggunakan media inkubasi berasal dari tanah yang diberi perlakuan dan dianalisis. Uji  fosfor  tanah menggunakan lima metode ekstraksi, yaitu metode Bray I (NH4F 0,03 N + HCl 0,025 N, nisbah 1:7); Bray II (NH4F 0,03 N + HCl 0,10 N ); Mehlich I (HCl 0,05 N + H2SO4 0,025 N); Morgan Wolf (NaC2H2H3O2.3H2O; pH 4,8); dan Truogh [HCl 0,10 N + (NH4)2SO4; pH 3]. Hasil penelitian menunjukkan adanya perbedaan yang nyata antara pengaruh perlakuan pupuk P terhadap parameter  tinggi tanaman,  jumlah daun, dan diameter batang tomat. Bobot segar biomassa dan bobot kering tomat juga menunjukkan  perbedaan pengaruh yang signifikan antarperlakuan. Nilai korelasi terbaik ditunjukkan oleh metode pengekstrak Mehlich I melalui parameter bobot kering dan bobot basah relatif tanaman. Dengan demikian, metode uji P tanah yang menggunakan Mehlich I dapat digunakan sebagai metode ekstraksi yang paling tepat untuk menganalisis unsur hara fosfor dengan koefisien korelasi 0,88, sehingga metode Mehlich I dapat diusulkan sebagai rekomendasi pemupukan P pada budidaya tomat pada tanah Inceptisols (nilai r = 0,89).  <br /><br />ABSTRACT. Izhar, L, Susila, AD, Purwoko, BS, Sutandi, A,  and  Mangku, IW. 2012. Determination of the Best Method of Soil P Test for Tomato (Lycopersicon esculentum Mill. L) on Inceptisols Soil. Phosphorus is one of important soil elements and application of the element in suitable concentration give high effect on tomato growth. A study on phosphorus analysis and its application for recommendation of soil fertilization of tomato cultivation on Inceptisols soil was conducted at the field and Greenhouse of Cikabayan, Bogor Agricultural University, from March to November 2010. The objective of this research was to obtain the best extraction method of soil-P test for determining phosphorus nutrient required for tomato cultivation on Inceptisol soil. Rate of phosphorus of 0X, ¼ X, ½ X, ¾ X, and 1X, where X was 368.5 kg/ha P2O5 with four replications, was applied in the study. The treatments were applied 6 months before planting date. The research was arranged in randomized complete block design. Analysis of correlation between soil-P and plant growth based on data collected from the plants grown in the greenhouse using incubation media in treated-soil was  analyzed. Soil-P test was carried out by using five extraction methods i.e. Bray I (HCl 0,025 N + NH4F 0.03), Bray II (NH4F 0.03 N + HCl 0.10 N), Mehlich I (HCl 0.05 N + H2SO4 0.025 N), Morgan Wolf (NaC2H2H3O2.3H2O; pH 4.8), and Truogh [HCl 0.10 N + (NH4)2SO4; pH 3]. The results showed that there were significant differences among the treatments of P fertilizer on the variables of plant height, leaf number, and stem diameter of tomato. Biomass fresh and dry weight of tomato also showed significantly different between the treatments applied. The highest correlation was shown on Mehlich I extraction reagent between plant dry and fresh weight. It means that, this P-nutrient extraction method was the most appropriate in determining phosphorus nutrient for tomatoes on Inceptisols soil with a coefficient correlation of 0.88. Mehlich I can also be used to develop a comprehensive phosphorus fertilizer recommendation for tomato cultivation on Inceptisols soil (r value = 0.89).<br /><br />



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 ◽  
2011 ◽  
Vol 49 (6) ◽  
pp. 523 ◽  
Author(s):  
W. J. Dougherty ◽  
S. D. Mason ◽  
L. L. Burkitt ◽  
P. J. Milham

There is a need to be able to identify soils with the potential to generate high concentrations of phosphorus (P) in runoff, and a need to predict these concentrations for modelling and risk-assessment purposes. Attempts to use agronomic soil tests such as Colwell P for such purposes have met with limited success. In this research, we examined the relationships between a novel soil P test (diffuse gradients in thin films, DGT), Colwell P, P buffering index (PBI), and runoff P concentrations. Soils were collected from six sites with a diverse range of soil P buffering properties, incubated for 9 months with a wide range of P additions, and then subjected to rainfall simulation in repacked trays growing pasture. For all soil and P treatment combinations, the relationship between DGT (0–10 mm) and runoff P was highly significant (P < 0.001, r2 = 0.84). Although there were significant curvilinear relationships between Colwell P and runoff P for individual soils, there were large differences in these relationships between soils. However, the inclusion of a P buffering measure (PBI) as an explanatory variable resulted in a highly significant model (P < 0.001, R2 = 0.82) that explained between-soil variability. We conclude that either DGT, or Colwell P and PBI, can be used to provide a relative measure of runoff P concentration.



Soil Research ◽  
2006 ◽  
Vol 44 (3) ◽  
pp. 277 ◽  
Author(s):  
W. J. Dougherty ◽  
D. M. Nash ◽  
D. J. Chittleborough ◽  
J. W. Cox ◽  
N. K. Fleming

The forms and stratification of soil phosphorus (P) and their relationship to mobile forms of P were investigated in soils collected from a subcatchment used for grazing of dairy cattle in the Adelaide Hills, South Australia. Phosphorus in the soils was highly stratified. The concentration of calcium chloride extractable P in the 0–0.01 m increment was, on average, 5.7 times greater than in the 0.05–0.10 m increment. Organic P (% of total P) in the top 0.01 m was significantly (P < 0.001) related to soil P content such that low P soils (total P of ~600 mg/kg) had high proportions of Po (~65%), whereas high P soils (total P of ~2000 mg/kg) had low proportions (~25%) of Po. Runoff P from these soils was predominantly (86%) dissolved (i.e. <0.45 μm). There was a significant (P < 0.001) exponential relationship between Olsen P in the top 0.01 m and dissolved P concentration in runoff. The form of dissolved P in runoff from soil in repacked trays was also significantly (P < 0.001) related to soil P. Runoff from low P soils (high Po) had high proportions (>50%) of dissolved unreactive P (DUP), whereas runoff from high P soils (low Po) had low proportions of DUP (<10%). Ultrafiltration of runoff samples revealed that 94 and 65% of the dissolved reactive P and DUP, respectively, was subcolloidal (i.e. <1 nm). These results highlight the relationship between soil fertility, the forms of soil P, and the concentrations and forms of P mobilised in runoff. Such relationships need to be considered in further studies of P mobilisation and the subsequent development of strategies designed to reduce runoff P concentrations.



2019 ◽  
Vol 103 (1) ◽  
pp. 43-45 ◽  
Author(s):  
Carlos Crusciol ◽  
João Rigon ◽  
Juliano Calonego ◽  
Rogério Soratto

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.



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