Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Assessment of methods for studying the dissolution of phosphate fertilizers of differing solubility in soil (1994)
    Springer
    Nutrient cycling in agroecosystems 38 (1994), S. 11-18 
    Details
    ISSN: 1573-0867
    Keywords: chemical extraction ; monocalcium phosphate ; partially acidulated phosphate rock ; phosphate dissolution ; phosphate rock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dissolution of three phosphate fertilizers, ground (〈150µm) North Carolina phosphate rock (NCPR), NCPR 30% acidulated with phosphoric acid (NCPAPR), and monocalcium phosphate (MCP) were studied using six chemical extraction methods, 0.5M NaOH followed by 1M HCl extractable P, 0.5M BaCl2 (buffered at pH = 8.1 with triethanolamine, BaCl2/TEA) extractable Ca, Olsen P, Bray I P and water extractable P. Two soils were used, Tekapo fine sandy loam and Craigieburn silt loam. Extractions were made after the fertilizers were incubated with the soils at the rates of 75,150 and 750µg P g−1 soil for 1, 8, 24, 51 and 111 days. Percentage dissolution of the PR-containing fertilizers was found to differ significantly between the extractants, 0.5M NaOH, 1M HCl and 0.5M BaCl2/TEA. These differences in estimated dissolution rates between methods were attributed to differences in the recovery rates of P or Ca between methods, which depended on the type of the extractant, soil P-retention capacity or Ca-saturation, and on the fertilizer application rate. No one method was found to be clearly better than others in studying PR dissolution in soils. The 0.5M NaOH extractable P was poorly related to water extractable P (R2 = 0.55 and 0.13 in Tekapo and Craigieburn soils respectively), Olsen P (R2 = 0.88 and 0.78) and Bray I P (R2= 0.88 and 0.78). The average rates of PR dissolution measured by the isotopic method (Fin) were higher than those measured by 0.5M NaOH, 1M HCl and 0.5M BaCl2/TEA methods for the periods of 1–50 and 50–111 days of soil-fertilizer contact. The descrepancy was attributed to a plant effect on PR dissolution and to a recycling effect of fertilizer P (i.e. fertilizer P which had been transformed to slowly exchangeable forms, during incubation, fluxing back to exchangeable P pool, during the labelling trial) both accounted for by Fin values but not by extraction-derived values. The changes of water extractable P, Bray I P and Olsen P with incubation time were in agreement with those predicted by Fin and Fout values. This suggests that Fin and Fout are two important parameters indicating the rates of phosphate release to and retention from plant available P pool.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750058
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Assessment of methods for studying the dissolution of phosphate fertilizers of differing solubility in soil (1994)
    Springer
    Nutrient cycling in agroecosystems 38 (1994), S. 19-27 
    Details
    ISSN: 1573-0867
    Keywords: chemical extraction ; isotopic exchange ; monocalcium phosphate ; partially acidulated phosphate rock ; phosphate dissolution ; phosphate rock ; plant response ; RAE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Relationships between plant response and rates of dissolution of ground (〈 150µm) North Carolina phosphate rock (NCPR), NCPR 30% acidulated with phosphoric acid (NCPAPR) and monocalcium phosphate (MCP) were assessed in pot experiments. The three fertilizers were incubated for 1, 50 and 111 days, at the rates of 75, 150 and 750µg P g−1 soil, using two soils with different P-retention capacity. After each period of incubation, four pots were set up from each treatment, and perennial ryegrass (Lolium perenne) was grown in a growth chamber for about six weeks to assess the agronomic effectiveness of the fertilizers. Results in dry matter yield and P uptake showed that immediately following application (1 day incubation), the MCP (solution) was supplying more P to plants than either the NCPR or the NCPAPR applied at the same rate. After 50 and 111 days of incubation, the NCPR and NCPAPR were just as effective in the lower P-retention Tekapo soil. The relative agronomic effectiveness (RAE) of the NCPR and NCPAPR compared with MCP was generally poorer in the higher P-retention Craigieburn soil than in the Tekapo soil shortly after application, but improved with time of incubation. Ryegrass responses to the application of the three fertilizers corresponded to the changing trends of exchangeable P in the soils, measured by the isotopic method. Regressions were made between plant P uptake and indices describing the intensity factor (water extractable P), quantity factor (Bray I P, Olsen P, 0.5M NaOH extractable P and isotopic exchangeable P) and the kinetic factor (Fin) of soil P supply to plants in the Tekapo soil. The percentage of variation in plant P uptake explained by individual indices was generally less than 80%, no matter which of the three single variable models, the Mitscherlich, the quadratic or the power function was fitted. However, more than 96% of the variation in plant P uptake in the Tekapo soil could be explained by the power function models involving two variables. The rate of P dissolution (Fin) determined by the isotopic dilution method was included in all the two variable models. The results suggest that assessment of soil P supply to plants should consider the kinetic factor in addition to the intensity and quantity factors, particularly where P fertilizers with differing solubility are applied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750059
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Assessment of methods for studying the dissolution of phosphate fertilizers of differing solubility in soil (1994)
    Springer
    Nutrient cycling in agroecosystems 38 (1994), S. 1-9 
    Details
    ISSN: 1573-0867
    Keywords: isotopic exchange ; monocalcium phosphate ; 32P ; partially acidulated phosphate rock ; phosphate release ; phosphate retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An isotopic exchange method, based on tracer kinetic theory, was used to study the dissolution (Fin) and retention (Fout) of Phosphate (P) fertilizers in the soil. This method involves labelling of the soil with carrier-free32P-phosphate ions, and monitoring changes with time of specific activity of isotopically exchangeable phosphate in the soil as extracted by plants, and of the amounts of readily exchangeable P. To assess this method, experiments were carried out to determine the rates of release and retention of phosphate from three fertilizers, monocalcium phosphate (MCP), ground North Carolina phosphate rock (NCPR 〈 150µm), and 30% acidulated (with phosphoric acid) NCPR (NCPAPR), in two soils, Tekapo fine sandy loam and Craigieburn silt loam. MCP was applied at 75 and 150µg g−1 soil; NCPR was applied at 150 and 750µg g−1 soil; and NCPAPR was applied at 150µg g−1 soil. After 1, 50 and 111 days of incubation, the treated soil samples were labelled with carrier-free32P-phosphate ions, and perennial ryegrass (Lolium perenne) was grown to sample specific activity in these samples. Results showed that the changing patterns of exchangeable P in the soils as affected by fertilizer solubility and application rate could be clearly explained by the values of Fin and Fout. With increasing period of soil-fertilizer contact, the P added in the form of MCP solution was rapidly transformed into non-exchangeable forms (high Fout value). Exchangeable P in the NCPR and NCPAPR treated soils were maintained at steady concentrations for extended periods due to the continued release of P from the fertilizer material (steady Fin) and lower rates of P retention by the soil (smaller Fout). The dissolution rate of NCPR at the lower application rate was smaller in absolute terms, but greater in relative terms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750057
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...