The agronomic value of products resulting from the partial acidulation of North Carolina phosphate rock with phosphoric acid

1985 ◽  
Vol 8 (1) ◽  
pp. 67-73 ◽  
Author(s):  
RC Stephen
Keyword(s):  
North Carolina ◽  
Phosphoric Acid ◽  
Phosphate Rock ◽  
Partial Acidulation ◽  
North Carolina Phosphate Rock

An isotope injection technique to measure agronomic effectiveness of different phosphate sources in undisturbed soils

1995 ◽  
Vol 35 (4) ◽  
pp. 489 ◽  
Author(s):  
HJ Di ◽  
R Harrison ◽  
AS Campbell
Keyword(s):  
North Carolina ◽  
Phosphate Rock ◽  
Specific Activity ◽  
P Uptake ◽  
Injection Technique ◽  
Agronomic Effectiveness ◽  
Single Superphosphate ◽  
Simple Method ◽  
North Carolina Phosphate Rock ◽  
Undisturbed Soils

This paper describes the use of an isotope injection technique for assessing the agronomic effectiveness of phosphate sources in undisturbed soils in field and glasshouse experiments. A special injection apparatus consisting of 20 syringe needles linked to a common reservoir was used to label soil cores 150 mm in diameter and 150 mm in height, without significantly disturbing the soil structure and established perennial ryegrass (Lolium perenne) root patterns. Variations in the amount of phosphorus (P) taken up by plants from single superphosphate (applied at 30, 60, and 100 kg P/ha), from 30% acidulated North Carolina phosphate rock (60 g P/ha), and from 'as received' North Carolina phosphate rock (60 kg P/ha) were indicated by the specific activity of the plant P. Percentages of plant P derived from the fertilisers were calculated on the basis of the specific activity of the fertilised treatments and the controls. The technique provides a simple method of comparing the agronomic effectiveness of phosphate sources in undisturbed soils and, unlike total dry matter yield and P uptake, is relatively unaffected by environmental factors.

The dissolution of North Carolina phosphate rock in some south-western Australian soils

1994 ◽  
Vol 38 (3) ◽  
pp. 249-253 ◽  
Author(s):  
J. C. Hughes ◽  
R. J. Gilkes
Keyword(s):  
North Carolina ◽  
Phosphate Rock ◽  
North Carolina Phosphate Rock ◽  
Western Australian

The agronomic effectiveness of reactive phosphate rocks 3. A comparison of application strategies for soluble phosphorus and reactive phosphate rock fertilisers

1997 ◽  
Vol 37 (8) ◽  
pp. 947 ◽  
Author(s):  
D. L. Garden ◽  
G. N. Ward ◽  
P. W. G. Sale ◽  
S. Tennakoon ◽  
R. P. Hindell ◽  
...  
Keyword(s):  
North Carolina ◽  
Phosphate Rock ◽  
Dry Matter ◽  
Early Years ◽  
Triple Superphosphate ◽  
Pasture Production ◽  
Soil P ◽  
North Carolina Phosphate Rock ◽  
Reactive Phosphate ◽  
Reactive Phosphate Rock

Summary. An investigation into the effectiveness of large (up to 80 kg P/ha), single dressings (capital applications) of different phosphorus (P) fertilisers, compared with smaller annual applications, was undertaken in the National Reactive Phosphate Rock Project. Yield comparisons were made at 23 permanent pasture sites across Australia using triple superphosphate, the highly reactive North Carolina phosphate rock and a partially acidulated form of North Carolina rock. Over 4 years, 19 of 23 sites showed no significant reduction in mean annual pasture yield with a single, large dressing applied in year 1 only, compared with an equivalent amount of total P applied in 4 annual applications. At a site in North Queensland, where the initial soil P level was very low, the large year-1 application of each fertiliser resulted in increased pasture production over that obtained from smaller annual applications because of increased pasture production in the early years. This amounted to an annual increase of between 1500 and 3000 kg dry matter/ha for the capital application strategy. The effectiveness of capital applications depended on soil, pasture and climatic conditions, and on the type of P fertiliser. Soil and environmental factors which appear to be important in determining the effect of capital applications are whether soils allow leaching of P (a function of rainfall and texture), whether they are P-sorbing (a function of clay content and soil mineralogy), the soil P content and how quickly it is being utilised by the pasture. Capital applications can be considered where P is not leached from the soil profile or where P sorption is low, and are most effective where soil P is low and there is a responsive pasture species present. Capital applications of water-soluble P fertiliser should not be considered on free-draining, low P-absorbing soils. Average annual pasture dry matter losses of about 2000 kg/ha occurred with a capital application of triple superphosphate compared with annual applications, at one such site in Tasmania. North Carolina phosphate rock was found to be the most effective P fertiliser for large capital applications, especially on free-draining, low P-absorbing soils.

An economic analysis of the field performance of North Carolina reactive phosphate rock compared with single superphosphate for selected sites from the National Reactive Phosphate Rock Project

1997 ◽  
Vol 37 (8) ◽  
pp. 1061 ◽  
Author(s):  
P. G. Simpson ◽  
P. W. G. Sale ◽  
S. B. Tennakoon
Keyword(s):  
North Carolina ◽  
Economic Analysis ◽  
Phosphate Rock ◽  
Financial Benefit ◽  
Single Superphosphate ◽  
Lag Effects ◽  
Soil P ◽  
North Carolina Phosphate Rock ◽  
Reactive Phosphate ◽  
Reactive Phosphate Rock

Summary. An economic analysis was undertaken using pasture yield data from 8 selected sites from the National Reactive Phosphate Rock Project, that encompassed 7 different performance scenarios for North Carolina phosphate rock. The aims were to determine whether the use of North Carolina phosphate rock in place of single superphosphate might result in a positive financial benefit in the 4th year, and after 4 years of annual applications of fertiliser. The analysis was carried out using annual P applications of North Carolina phosphate rock and single superphosphate, that resulted in pasture yields equivalent to 50, 70 or 90% of the maximum yield response of single superphosphate in the 4th year. Annual pasture dry matter yields, produced by these fertiliser applications, were converted to stocking rates, and dollar incomes were derived by applying appropriate gross margins. The analysis was also undertaken to determine the financial benefit from large, year-1 applications of North Carolina phosphate rock. Single superphosphate was priced at $168/t while North Carolina phosphate rock plus sulfur was priced at $180/t. The economic analysis found that a positive financial benefit with North Carolina phosphate rock occurred for only one scenario where the agronomic performance of North Carolina phosphate rock and single superphosphate were equivalent in the 4th year of annual fertiliser application. For 3 other scenarios where the performance of North Carolina phosphate rock and single superphosphate were also equivalent in the 4th year, the economic performance of North Carolina phosphate rock was poor due to (i) a ‘lag’ effect where pasture yield with North Carolina phosphate rock was generally less than that with single superphosphate in years 1–3, and/or to (ii) a seasonal effect where the autumn–early winter pasture responses with North Carolina phosphate rock were less than those with single superphosphate, necessitating a reduction in annual stocking rates on the North Carolina phosphate rock-fertilised pasture. A key finding was that large, single, year-1 applications of North Carolina phosphate rock generally overcame these seasonal and/or yearly lag effects, and led to positive financial benefits from North Carolina phosphate rock applied in this way. Annual applications of North Carolina phosphate rock were economically viable at sandy, high rainfall sites where water-soluble P from single superphosphate would be readily leached from the root zone, provided that the soil P status was adequate and conditions were conducive to reactive phosphate rock dissolution. However, North Carolina phosphate rock was not an economically viable fertiliser to apply annually at (i) non-leaching sites where the soil P status was low and marked yield penalties occurred in the first few years of North Carolina phosphate rock use, (ii) where the soil had a very high P-sorption capacity, and (iii) where North Carolina phosphate rock dissolution was restricted by low rainfall or high pH. The inclusion of estimated residual P value had only a small impact on the economic outcome for scenarios which had not already performed poorly due to seasonal or lag effects.

The effect of soil texture on the dissolution of North Carolina phosphate rock

1988 ◽  
Vol 39 (2) ◽  
pp. 191-198 ◽  
Author(s):  
I. A. K. KANABO ◽  
R. J. GILKES
Keyword(s):  
North Carolina ◽  
Soil Texture ◽  
Phosphate Rock ◽  
North Carolina Phosphate Rock

National Reactive Phosphate Rock Project —aims, experimental approach and site characteristics

1997 ◽  
Vol 37 (8) ◽  
pp. 885 ◽  
Author(s):  
M. J. McLaughlin ◽  
N. K. Fleming ◽  
P. G. Simpson ◽  
M. D. A. Bolland ◽  
R. J. Gilkes ◽  
...  
Keyword(s):  
North Carolina ◽  
Formic Acid ◽  
Phosphate Rock ◽  
Soil Phosphorus ◽  
Triple Superphosphate ◽  
Phosphate Rocks ◽  
Agronomic Effectiveness ◽  
North Carolina Phosphate Rock ◽  
Reactive Phosphate ◽  
Reactive Phosphate Rock

Summary. Field-based cutting trials, which formed part of the National Reactive Phosphate Rock Project, were established across Australia in a range of environments to evaluate the agronomic effectiveness of 5 phosphate rocks, and 1 partially acidulated phosphate rock, relative to either single superphosphate or triple superphosphate. The phosphate rocks differed in reactivity. Sechura (Bayovar) and North Carolina phosphate rocks were highly reactive (>70% solubility in 2% formic acid), whilst Khouribja (Moroccan) and Hamrawein (Egypt) phosphate rock were moderately reactive. Duchess phosphate rock from Queensland was relatively unreactive (<45% solubility in 2% formic acid). Phosphate rock effectiveness was assessed by measuring pasture production over a range of phosphorus levels, and by monitoring bicarbonate-soluble phosphorus extracted from soil samples collected before the start of each growing season. Other treatments included single large applications of triple superphosphate, partially acidulated phosphate rock and North Carolina phosphate rock applied at 2 rates, and the application of monocalcium phosphate and North Carolina phosphate rock sources without sulfur to evaluate the importance of sulfur in the potential use of phosphate rock fertilisers at each site. A broad range of environments were represented over the 30 sites which were based on pastures using annual and/or perennial legumes and perennial grasses. Rainfall across the network of sites ranged from 560 to 4320 mm, soil pH (CaCl2) from 4.0 to 5.1, and Colwell-extractable phosphorus ranged from 3 to 47 µg/g before fertiliser application. Two core experiments were established at each site. The first measured the effects of phosphate rock reactivity on agronomic effectiveness, while the second measured the effects of the degree of water solubility of the phosphorus source on agronomic effectiveness. The National Reactive Phosphate Rock Project trials gave the opportunity to confirm the suitability of accepted procedures to model fertiliser response and to develop new approaches for comparing different fertiliser responses. The Project also provided the framework for subsidiary studies such as the effect of fertiliser source on soil phosphorus extractability, cadmium and fluorine concentrations in herbage, evaluation of soil phosphorus tests, and the influence of particle size on phosphate rock effectiveness. The National Reactive Phosphate Rock Project presents a valuable model for a large, Australia-wide, collaborative team approach to an important agricultural issue. The use of standard and consistent experimental methodologies at every site ensured that maximum benefit was obtained from data generated. The aims, rationale and methods used for the experiments across the network are presented and discussed.

The influence of the addition of goethite to soil on the dissolution of North Carolina phosphate rock

Soil Research ◽  
1987 ◽  
Vol 25 (3) ◽  
pp. 313 ◽  
Author(s):  
IAK Kanabo ◽  
RJ Gilkes
Keyword(s):  
North Carolina ◽  
Laboratory Experiment ◽  
Phosphate Rock ◽  
Contact Period ◽  
North Carolina Phosphate Rock ◽  
Exchangeable Ca ◽  
Soluble P ◽  
P Retention

This laboratory experiment investigated changes in the dissolution of North Carolina phosphate rock and NaHCO3-soluble P arising from the addition of goethite (�-FeOOH) to soil. Increasing goethite in the soil increased the amount of phosphate rock (PR) dissolution as measured by the increase in exchangeable Ca (�Ca) values. Increased dissolution was, however, associated with decreased NaHCO3- soluble P due to P retention by goethite. The proportion of P dissolved from PR that was soluble in 0.5 M NaHCO3 solution decreased with contact period and with increased goethite. The increase in exchangeable Ca (�Ca) was a better indicator of the extent of PR dissolution in goethite-containing soils than NaHCO3-soluble P.

Agronomic effectiveness of a partially acidulated reactive phosphate rock fertiliser

1997 ◽  
Vol 37 (8) ◽  
pp. 985 ◽  
Author(s):  
D. C. Lewis ◽  
P. W. G. Sale ◽  
D. Johnson
Keyword(s):  
North Carolina ◽  
Phosphate Rock ◽  
Agronomic Effectiveness ◽  
Permanent Pasture ◽  
North Carolina Phosphate Rock ◽  
Reactive Phosphate ◽  
Reactive Phosphate Rock ◽  
Papr Performance ◽  
Yield Responses ◽  
Very High

Summary. The agronomic effectiveness of a partially acidulated phosphate rock (PAPR), produced by the 50% acidulation of North Carolina phosphate rock with sulfuric acid, was compared over 4 growing seasons with triple superphosphate (TSP) and the highly reactive North Carolina phosphate rock at 22 permanent pasture sites in the National Reactive Phosphate Rock Project. The performance of PAPR as a phosphorus (P) fertiliser for permanent pasture was determined by calculating the substitution value of TSP for PAPR at 50% of the maximum yield response for TSP from the fitted annual dry matter response curves. PAPR performance varied both between sites, and between years at individual sites. Annual yield responses with PAPR were larger than those with TSP at 1 high rainfall site where water-soluble P from TSP was thought to leach from the root zone. PAPR was superior to TSP at another site and generally similar in effectiveness to TSP at 4 sites with light-textured, low or medium P-sorbing soils with a moderate annual rainfall (500–750 mm). The mean substitution value over the 4 years for these sites was >0.9. PAPR performance at other sites where highly reactive phosphate rocks were effective in the short or medium term was variable: there were equivalent yield responses to TSP in some years but much smaller yield responses in other years. PAPR performed very poorly in a third group of sites where the soil had a high to very high P sorption capacity or where there was a very high demand for fertiliser P due to large legume responses on a P-deficient soil. Although generally inferior to TSP, the PAPR was more effective than North Carolina phosphate rock at the majority of sites during the 4-year study.

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