Unacidulated and Partially acidulated phosphate rock: Agronomic effectiveness and the rates of dissolution of phosphate rock

1992 ◽  
Vol 33 (3) ◽  
pp. 267-277 ◽  
Author(s):  
S. S. S. Rajan ◽  
J. H. Watkinson
Keyword(s):  
Phosphate Rock ◽  
Partially Acidulated Phosphate Rock ◽  
Agronomic Effectiveness

Agronomic effectiveness of partially acidulated phosphate rock as influenced by soil phosphorus-fixing capacity

1989 ◽  
Vol 120 (2) ◽  
pp. 159-164 ◽  
Author(s):  
S. H. Chien ◽  
L. L. Hammond
Keyword(s):  
Phosphate Rock ◽  
Soil Phosphorus ◽  
Partially Acidulated Phosphate Rock ◽  
Agronomic Effectiveness

Agronomic effectiveness of partially acidulated phosphate rock fertilisers in selected New Zealand soils

1995 ◽  
Vol 35 (3) ◽  
pp. 387 ◽  
Author(s):  
LM Condron ◽  
HJ Di ◽  
KM Goh ◽  
AS Campbell ◽  
R Harrison
Keyword(s):  
New Zealand ◽  
Phosphate Rock ◽  
Phosphorus Uptake ◽  
Partially Acidulated Phosphate Rock ◽  
Agronomic Effectiveness ◽  
Single Superphosphate ◽  
Relative Agronomic Effectiveness ◽  
Pot Trials ◽  
Highly Correlated ◽  
Manufacture Plant

The agronomic performances of some longlife superphosphate (LSP) and partially acidulated phosphate rock (PAPR) fertilizers were compared with single superphosphate in glasshouse pot trials over 9-10 months using a range of New Zealand soils. The fertilizers used differed in the type (origin) of phosphate rock (PR), the acid to rock ratio used in the production of LSP, percentage acidulation of PAPR, and incorporation of elemental sulfur into LSP. The agronomic effectiveness of the fertilizers studied was primarily influenced by the type of PR and percentage acidulation of PAPR, but not by the acid to rock ratio. Variations in the agronomic effectiveness of LSP and PAPR fertilizers made from different PRs did not reflect the relative solubilities of the original PRs. This was mainly attributed to alterations in the chemistry and consequent solubility of PR which occurred during fertilizer manufacture. Plant phosphorus uptake was highly correlated with fertilizer solubility in 2% citric and 2% formic acids. The relative agronomic effectiveness of LSP and PAPR fertilizers was not significantly related to any single soil property.

The agronomic effectiveness of reactive phosphate rocks 1. Effect of the pasture environment

1997 ◽  
Vol 37 (8) ◽  
pp. 921 ◽  
Author(s):  
P. W. G Sale ◽  
R. J. Gilkes ◽  
M. D. A. Bolland ◽  
P. G. Simpson ◽  
D. C. Lewis ◽  
...  
Keyword(s):  
North Carolina ◽  
Phosphate Rock ◽  
Surface Soil ◽  
Annual Rainfall ◽  
Triple Superphosphate ◽  
Agronomic Effectiveness ◽  
P Sorption ◽  
Reactive Phosphate ◽  
Reactive Phosphate Rock ◽  
Very High

Summary. The agronomic effectiveness of directly applied North Carolina reactive phosphate rock was determined for 4 years from annual dry matter responses at 26 permanent pasture sites across Australia as part of the National Reactive Phosphate Rock Project. Fertiliser comparisons were based on the substitution value of North Carolina reactive phosphate rock for triple superphosphate (the SV50). The SV50 was calculated from fitted response curves for both fertilisers at the 50% of maximum yield response level of triple superphosphate. The reactive phosphate rock was judged to be as effective as triple superphosphate in the 1st year (and every year thereafter) at 4 sites (SV50 >0.9), and was as effective by the 4th year at 5 sites. At another 9 sites the reactive phosphate rock was only moderately effective with SV50 values between 0.5 and 0.8 in the 4th year, and at the final 8 sites it performed poorly with the 4th year SV50 being less than 0.5. Pasture environments where the reactive phosphate rock was effective in the 1st year were: (i) those on sandy, humic or peaty podsols with an annual rainfall in excess of 850 mm; (ii) those on soils that experienced prolonged winter inundation and lateral surface flow; and (iii) tropical grass pastures in very high rainfall areas (>2300 mm) on the wet tropical coast on North Queensland. The highly reactive North Carolina phosphate rock became effective by the 4th year at sites in southern Australia where annual rainfall exceeded 700 mm, and where the surface soil was acidic [pH (CaCl2) <5.0] and not excessively sandy (sand fraction in the A1 horizon <67%) but had some phosphorus (P) sorption capacity. Sites that were unsuitable for reactive phosphate rock use in the medium term (up to 4 years at least) were on very high P-sorbing krasnozem soils or high P-sorbing lateritic or red earth soils supporting subterranean-clover-dominant pasture, or on lower rainfall (< 600 mm) pastures growing on soils with a sandy A1 horizon (sand component >84%). No single environmental feature adequately predicted reactive phosphate rock performance although the surface pH of the soil was most closely correlated with the year-4 SV50 (r = 0.67). Multiple linear regression analysis found that available soil P (0–10 cm) and the P sorption class of the surface soil (0–2 cm), together with annual rainfall and a measure of the surface soil"s ability to retain moisture, could explain about two-thirds of the variance in the year-4 SV50 . The results from this Project indicate that there are a number of specific pasture environments in the higher rainfall regions of Australia where North Carolina reactive phosphate rock can be considered as an effective substitute P fertiliser for improved pasture.

Reactions of Partially Acidulated Phosphate Rock with Soils from the Tropics

1980 ◽  
Vol 44 (3) ◽  
pp. 477-482 ◽  
Author(s):  
A. Uzo Mokwunye ◽  
S. H. Chien
Keyword(s):  
Phosphate Rock ◽  
Partially Acidulated Phosphate Rock ◽  
The Tropics

Long-term greenhouse evaluation of partially acidulated phosphate rock fertilizers

1987 ◽  
Vol 13 (1) ◽  
pp. 31-44 ◽  
Author(s):  
D. K. Friesen ◽  
P. W. G. Sale ◽  
G. J. Blair
Keyword(s):  
Phosphate Rock ◽  
Partially Acidulated Phosphate Rock ◽  
Greenhouse Evaluation
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