Growth and yield of sugarcane as a function of phosphorus doses and forms of application

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.

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Effects of Combinations of Triple Superphosphate and a Reactive Phosphate Rock on Yield and Phosphorus Uptake by Corn

Soil Science Society of America Journal ◽

10.2136/sssaj1987.03615995005100060045x ◽

1987 ◽

Vol 51 (6) ◽

pp. 1656-1658 ◽

Cited By ~ 32

Author(s):

S. H. Chien ◽

F. Adams ◽

F. E. Khasawneh ◽

J. Henao

Keyword(s):

Phosphate Rock ◽

Phosphorus Uptake ◽

Triple Superphosphate ◽

Reactive Phosphate ◽

Reactive Phosphate Rock

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An appraisal of the National Reactive Phosphate Rock Project

Australian Journal of Experimental Agriculture ◽

10.1071/ea96122 ◽

1997 ◽

Vol 37 (8) ◽

pp. 1085

Author(s):

D. J. Reuter

Keyword(s):

Expert System ◽

Phosphate Rock ◽

Field Experiments ◽

Water Soluble ◽

Annual Rainfall ◽

Yield Response ◽

Triple Superphosphate ◽

Reactive Phosphate ◽

Independent Field ◽

Reactive Phosphate Rock

Summary. An expert system has been developed, using the results from the National Reactive Phosphate Rock Project, to determine whether reactive phosphate rock is likely to be an effective substitute for water-soluble superphosphate fertiliser for a given pasture environment. The evaluation is made from site information [annual rainfall, pasture composition and the likelihood of phosphorus (P) leaching], and soil information (pH, Colwell P, soil colour and field texture). The expert system can determine the effectiveness of both highly reactive and moderately reactive phosphate rocks. Observed substitution values of triple superphosphate for the highly reactive North Carolina phosphate rock (ratio of the respective P levels required to produce 50% of the maximum observed yield response to triple superphosphate) were closely related to values predicted by the expert system (r = 0.92); the relationship between observed and predicted substitution values of single superphosphate for the moderately reactive Hemrawein phosphate rock was also close (r= 0.86). The expert system gives one of 4 different recommendations for reactive phosphate rock based on the magnitude of the predicted substitution values. These are ‘immediately effective’, ‘effective in the medium term’, ‘marginally effective’, and ‘not effective’. The system was validated using the results from independent field experiments that provided measures of the effectiveness of reactive phosphate rock at different pasture sites.

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

Australian Journal of Experimental Agriculture ◽

10.1071/ea96110 ◽

1997 ◽

Vol 37 (8) ◽

pp. 947 ◽

Cited By ~ 2

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.

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Building an expert system to advise on the use of reactive phosphate rock on Australian pastures

Australian Journal of Experimental Agriculture ◽

10.1071/ea96121 ◽

1997 ◽

Vol 37 (8) ◽

pp. 1077 ◽

Cited By ~ 4

Author(s):

P. Gillard ◽

P. W. G. Sale ◽

S. B. Tennakoon

Keyword(s):

Expert System ◽

Phosphate Rock ◽

Field Experiments ◽

Water Soluble ◽

Annual Rainfall ◽

Yield Response ◽

Triple Superphosphate ◽

Reactive Phosphate ◽

Independent Field ◽

Reactive Phosphate Rock

Summary. An expert system has been developed, using the results from the National Reactive Phosphate Rock Project, to determine whether reactive phosphate rock is likely to be an effective substitute for water-soluble superphosphate fertiliser for a given pasture environment. The evaluation is made from site information [annual rainfall, pasture composition and the likelihood of phosphorus (P) leaching], and soil information (pH, Colwell P, soil colour and field texture). The expert system can determine the effectiveness of both highly reactive and moderately reactive phosphate rocks. Observed substitution values of triple superphosphate for the highly reactive North Carolina phosphate rock (ratio of the respective P levels required to produce 50% of the maximum observed yield response to triple superphosphate) were closely related to values predicted by the expert system (r = 0.92); the relationship between observed and predicted substitution values of single superphosphate for the moderately reactive Hemrawein phosphate rock was also close (r= 0.86). The expert system gives one of 4 different recommendations for reactive phosphate rock based on the magnitude of the predicted substitution values. These are ‘immediately effective’, ‘effective in the medium term’, ‘marginally effective’, and ‘not effective’. The system was validated using the results from independent field experiments that provided measures of the effectiveness of reactive phosphate rock at different pasture sites.

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Summary of eleven long-term field trials with 'Longlife' phosphatic fertiliser

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.1992.54.2041 ◽

1992 ◽

pp. 35-40

Author(s):

S.F. Ledgard ◽

B.S. Thorrold ◽

A.G. Sinclair ◽

S.S.S. Rajan ◽

D.C. Edmeades

Keyword(s):

New Zealand ◽

Phosphate Rock ◽

Field Trials ◽

Triple Superphosphate ◽

Single Superphosphate ◽

The North ◽

Reactive Phosphate ◽

Reactive Phosphate Rock ◽

Term Field

Longlife' phosphatic fertiliser is manufactured in New Zealand by mixing reactive phosphate rock (RPR) with single superphosphate (SSP) when the SSP is at an ex-den stage. Commercially produced Longlife (70:30 SSP:RPR) was evaluated in 6 field mowing trials in the North Island over 3 or4 years. Also, a 5050 (SSP:RPR) Longlife-type product was examined in 5 field trials throughout New Zealand over 5 or 6 years. Longlife was compared against SSP and/or triple superphosphate (TSP) in all trials, and RPR treatments were included in 7 trials. In all trials with commercially produced Longlife, the pasture response to Longlife tended to be less than that to SSP or TSP in the first 2 years and was significantly different (P 6.0 and/or rainfall ~800 mm/year). Keywords field trials, Longlife, phosphate, reactive phosphate rock, superphosphate

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

Australian Journal of Experimental Agriculture ◽

10.1071/ea96105 ◽

1997 ◽

Vol 37 (8) ◽

pp. 885 ◽

Cited By ~ 5

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.

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