Chemical effects in the assessment of phosphate rock residues extracted from multicomponent fertilisers

1992 ◽  
Vol 32 (3) ◽  
pp. 343-350
Author(s):  
A. C. Braithwaite ◽  
A. C. Eaton ◽  
P. S. Groom
Keyword(s):  
Phosphate Rock ◽  
Chemical Effects ◽  
Phosphate Rock Residues

scholarly journals Utilisation of inorganic and organic soil phosphorus in a hill country soil

1992 ◽  
pp. 65-69 ◽  
Author(s):  
K.W. Perrott
Keyword(s):  
Phosphate Rock ◽  
Organic Phosphorus ◽  
Soil Phosphorus ◽  
Organic Soil ◽  
Inorganic Phosphorus ◽  
P Fractions ◽  
Inorganic P ◽  
Soil P ◽  
Hill Country ◽  
Phosphate Rock Residues

Changes in phosphorus (P) fractions of unfertilised and fertilised (superphosphate) soil were investigated over five years at a hill country site near Te Kuiti. Only soil inorganic P (Pi) reserves were utilised for plant uptake when superphosphate was withheld at the site. Immobilisation of P as soil organic P (PO) contributed to depletion of the soil Pi reserves during the first two years of this trial. Where superphosphate was applied, immobilisation of P as PO amounted to about 25% of applied P during the five years measurements were made. Changes in soil P fractions indicated that all forms of soil Pi were utilised when superphosphate was withheld. These included readily available Pi, Al- Pi, Fe-Pi, and residual phosphate rock from previous fertiliser applications. Depletion of the phosphate rock residues in the soil also occurred where superphosphate was applied and appears to have been completed within about two years. The phosphate rock residues had probably accumulated because of the relatively high amounts of unacidulated phosphate rock in superphosphate manufactured before 1983. Accumulation of Po associated with humic acid, or adsorbed on surfaces of hy drous oxides of Al and Fe, occurred in both fertilised and unfertilised soils. The more labile forms of PO also increased in the fertilised soil. Keywords inorganic phosphorus, organic phosphorus, phosphorus immobilisation, soil phosphorus, soil phosphorus fractions, soil phosphorus utilisation.

CHEMICAL EFFECTS IN MULTIELECTRON PROCESSES IN THE FLUORIDE ANION

1987 ◽  
Vol 48 (C9) ◽  
pp. C9-777-C9-780
Author(s):  
R. HESSABI ◽  
D. URCH
Keyword(s):  
Fluoride Anion ◽  
Chemical Effects

ALTERNATIVE P-FERTILISERS FOR NORTHLAND SOILS

1986 ◽  
pp. 229-232
Author(s):  
P.W. Shannon
Keyword(s):  
Phosphate Rock ◽  
Growth Responses ◽  
Triple Superphosphate ◽  
Rock Phosphates ◽  
Distribution Costs ◽  
Phosphate Retention ◽  
Sechura Phosphate Rock ◽  
Local Product ◽  
Application Frequency ◽  
Chatham Rise Phosphorite

Increasing material, processing, and distribution costs have raised superphosphate prices to a point where many farms cannot support the costs of meeting maintenance phosphate requires men& Alternatives to superphosphate, particularly those that have lower processing costs and contain more P, may offer a solution to the problem provided they are agronomically as effective. Phosphate rock may indeed be such an alternative. Preliminary results from a series of five trials in Northland show that on soils of moderate P fertility, with low phosphate retention (PR) and high pH (5.9.6.0), initial pasture growth responses to rock phosphates are smaller than those from single or triple superphosphate. On one soil of higher PR and lower pH, the differences in yield between the rock-phosphates and the super. phosphates were smaller. Of the rock phosphates tested, Sechura and North Carolina (unground and ungranulated) tended to be more effective than ground and granulated Chatham Rise phosphorite. The effect on production of applying fertilisers once every three years, as opposed to annual applications is being investigated using triple superphosphate and Sechura phosphate rock. After two years, production levels appear largely unaffected by differences in application frequency. A comparison of locally-produced superphosphate with a reference standard showed that both performed similarly, indicating that the local product was of satisfactory quality.

Uranium in phosphate rock

1975 ◽  
Author(s):  
James Bachelder Cathcart
Keyword(s):  
Phosphate Rock

A summary of phosphate-rock resources of the United States; an analysis of past estimates

1981 ◽  
Author(s):  
James Bachelder Cathcart ◽  
Richard Porter Sheldon ◽  
Robert A. Gulbrandsen
Keyword(s):  
United States ◽  
Phosphate Rock ◽  
The United States
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