scholarly journals The long-term effectiveness of reactive phosphate rock as a phosphate fertiliser for New Zealand pastures

1990 ◽  
pp. 101-104 ◽  
Author(s):  
A.G. Sinclair ◽  
C.B. Dyson ◽  
P.W. Shannon
Keyword(s):  
New Zealand ◽  
Phosphate Rock ◽  
Field Trials ◽  
Superior Performance ◽  
Single Superphosphate ◽  
Reactive Phosphate ◽  
Application Rates ◽  
Phosphate Retention ◽  
Reactive Phosphate Rock ◽  
Sechura Phosphate Rock

Sechura reactive phosphate rock (SPR) and triple superphosphate (TSP) have been compared as phosphate fertihsers for pastures in a series of 19 field trials dispersed throughout New Zealand, each continuing for 3-6 years. Both fertilisers were applied annuaIly at 4 rates. In the first 2 years SPR was much less effective at increasing dry matter yields than TSP, but its performance improved markedly with time. In year 6 SPR outyielded TSP at alI application rates for all sites combined. The relative performance of SPR and TSP differed markedly at different sites. Very high soil phosphate retention and a combination of low moisture and high pH appeared to be unfavourable for SPR performance. In most sites SPR was equal or superior to TSP by year 6. SPR substantially raised molybdenum concentration in clovers, and this may have contributed to its superior performance at some sites. As TSP and single superphosphate were equally effective, the good performauce of SPR and the relative cheapness of reactive phosphate rocks suggest an important role for the latter on New Zealand pastures. Keywords Sechura phosphate rock, reactive phosphate rock, RPR, superphosphates, phosphate fertilisers

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

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

RPR revisited (1): Research, recommendations, promotion and use in New Zealand

2012 ◽  
pp. 255-268
Author(s):  
B.F. Quin ◽  
M. Zaman
Keyword(s):  
New Zealand ◽  
Phosphate Rock ◽  
Field Trials ◽  
Laboratory Research ◽  
Reactive Phosphate ◽  
Run Off ◽  
Specific Advice ◽  
Reactive Phosphate Rock ◽  
Research Recommendations

Reactive phosphate rock (RPR) has been studied extensively in field trials and laboratory research in New Zealand since the 1930s. This paper looks at the different approaches to research over the decades, at what conclusions were drawn, at the recommendations made to farmers, and at the commercial promotion and sales of RPR. It is not an exhaustive literature review, but sufficiently comprehensive to demonstrate the large amount of research conducted, and to document the important issues that have arisen, particularly with respect to advice being given to farmers. RPR research has suffered from a series of mishaps which have hindered, in one way or another, the results being accurately interpreted and passed on clearly to farmers. There is a need for specific advice for farmers regarding managing or minimising any lag in production following a switch to RPR. New Zealand's grazed pastures, water quality and "clean and green" image internationally are closely interlinked. Given the proven significant reduction in P losses in run-off to waterways with RPR, the conditions in which RPR can be successfully used in New Zealand's pastoral agriculture have been reassessed. Key words: reactive phosphate rock, RPR, superphosphate, SSP, TSP, PAPR, long-term comparisons, plot trials, grazing trials, fertiliser recommendations, history

scholarly journals Phosphorus status of pastoral soils where reactive phosphate rock fertilisers have been used

1995 ◽  
pp. 133-137
Author(s):  
K.W. Perrott ◽  
B.E. Kerr ◽  
J.H. Watkinson ◽  
J.E. Waller
Keyword(s):  
Dissolution Rate ◽  
Phosphate Rock ◽  
Linear Regression Analysis ◽  
Soil Test ◽  
Site Factors ◽  
Soil P ◽  
Reactive Phosphate ◽  
Reactive Phosphate Rock ◽  
Sechura Phosphate Rock ◽  
Fertiliser Application

The dissolution rate of Sechura phosphate rock (particle size 75-150 pm) was determined at 95 New Zealand sites with a range of soil and environmental properties. Rates ranged from 0 to 70% of the phosphate rock dissolved per year with an average dissolution rate of 3 1 %/year. An initial model based on stepwise linear regression analysis indicated that the rate of dissolution was negatively associated with soil pH and positively associated with rainfall and exchangeable soil magnesium. There was also an effect of soil type and drainage. The amount of residual RPR accumulated from previous fertiliser application can be determined by a new soil test. This, together with the dissolution rate estimated from the nature of the RF'R and the soil and site factors, can be used to indicate likely soil P status. Keywords: dissolution, fertiliser, phosphorus, reactive phosphate rock, soil test

scholarly journals Response to re-application of phosphate fertilisers on hill pasture where fertiliser had been withheld for seven years

1993 ◽  
pp. 67-71
Author(s):  
S.F. Ledgard ◽  
G.J. Brier
Keyword(s):  
Phosphate Rock ◽  
Nitrogen Availability ◽  
Research Area ◽  
N Fixation ◽  
Single Superphosphate ◽  
Pasture Production ◽  
Hill Country ◽  
Reactive Phosphate ◽  
Reactive Phosphate Rock ◽  
P Rate

A field experiment at the AgResearch Te Kuiti Research Area examined effects of re-application of phosphorus (P) fertilisers on production and composition of hill pastures (1520% slope) which had received no P for 7 years. Treatments were 0, 20, 40 and 80 kg P/ha/year as single superphosphate (SSP) or North Carolina reactive phosphate rock (RPR). The soil was a yellowbrown earth/yellow-brown loam intergrade with Olsen P 9. Re-application of P produced a rapid and large increase in pasture production of up to 42 and 61% in years 1 and 2, respectively, and brought production up to 95% of that measured in neighbouring regularly fertilised paddocks. The pasture response to RPR was less (PcO.01) than that to SSP in both years, particularly at the highest rate. This indicated that RPR was less suitable for capital application. The P response was due almost entirely to an increase in white clover growth, and N, fixation was estimated to increase from 30 to 130 kg N/ha/year. In year 2, there was an increase in ryegrass content of pasture receiving the high P rate and this was attributed to increased nitrogen availability due to increased N, fixation. Keywords: hill country, phosphorus, reactive phosphate rock, superphosphate

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 use of substitution values for characterising fertiliser performance

1997 ◽  
Vol 37 (8) ◽  
pp. 913
Author(s):  
D. A. Ratkowsky ◽  
S. B. Tennakoon ◽  
P. W. G. Sale ◽  
P. G. Simpson
Keyword(s):  
Phosphate Rock ◽  
Statistical Tests ◽  
Effective Means ◽  
Field Trials ◽  
Water Soluble ◽  
Soluble Phosphate ◽  
Phosphate Rocks ◽  
High Performing ◽  
Reactive Phosphate ◽  
Reactive Phosphate Rock

Summary. The substitution value, or horizontal comparison between a fertiliser and some high-performing reference fertiliser, is shown to be a powerful and effective means of ranking the performance of various reactive phosphate rock fertilisers relative to a water-soluble phosphate such as a superphosphate. To take account of the variability due to random error in fertiliser field trials, the use of a standardised score, one measuring the relative departure of the substitution value from that expected for the standard fertiliser, is shown to be a suitable statistic for general use. Cluster analyses using these z-scores as input data can lead to appropriate decision making such as, for example, grouping experimental sites into: (i) those which perform as well as water-soluble phosphate, (ii) those which are somewhat worse than water-soluble phosphate, and (iii) those which are much worse than water-soluble phosphate. Substitution values obtained for different reactive phosphate rocks were compared both within and between sites, using appropriate statistical tests of significance. This approach assisted in ranking the performance of the 5 reactive phosphate rocks and the partially acidulated phosphate rock studied in the National Reactive Phosphate Rock Project, and helped predict which ones are likely to be suitable for use in differing environments.

Effect of fertiliser type on cadmium and fluorine concentrations in clover herbage

1997 ◽  
Vol 37 (8) ◽  
pp. 1019 ◽  
Author(s):  
M. J. McLaughlin ◽  
P. G. Simpson ◽  
M. K. Smart ◽  
N. Fleming ◽  
D. P. Stevens ◽  
...  
Keyword(s):  
North Carolina ◽  
Phosphate Rock ◽  
Partially Acidulated Phosphate Rock ◽  
Single Superphosphate ◽  
North Carolina Phosphate Rock ◽  
Reactive Phosphate ◽  
Reactive Phosphate Rock

Summary. This study investigated whether changing phosphatic fertiliser type affects the accumulation of cadmium (Cd) and fluorine (F) in pasture herbage. North Carolina phosphate rock, and partially acidulated fertilisers derived from this rock, generally have higher Cd and F concentrations compared with single superphosphate currently manufactured in Australia. Clover herbage from sites of the National Reactive Phosphate Rock trial was collected and analysed for concentrations of Cd (11 sites) and F (4 sites). A comparison was made between pastures fertilised with 4 rates of single superphosphate, North Carolina phosphate rock, and partially acidulated phosphate rock having Cd concentrations of 283, 481 and 420 mg/kg P respectively, and F concentrations of 170, 271 and 274 g/kg P respectively. One site used Hamrawein (Egypt) phosphate rock (HRP) having a Cd and F concentration of 78 mg Cd/kg P and 256 g F/kg P respectively. To help identify differences in herbage Cd concentrations between sites, unfertilised soils from each site were analysed for total and extractable Cd contents. At one site Cd concentrations in bulk herbage (clover, grasses and weeds) were related to infestation of the pasture by capeweed (Arctotheca calendula L. Levyns). There were no significant differences between F in herbage from plots fertilised with either single superphosphate, partially acidulated phosphate rock or North Carolina phosphate rock, or between sites. Concentrations of F in herbage were low, generally less than 10 mg/kg. However, there were large differences in Cd concentrations in herbage between sites, while differences between fertiliser treatments were small in comparison. The site differences were only weakly related to total or extractable (0.01 mol CaCl2/L) Cd concentrations in soil. Significant differences in Cd concentrations in clover due to fertiliser type were found at 5 sites. North Carolina phosphate rock treatments had significantly higher Cd concentrations in clover compared with single superphosphate at 2 sites. Partially acidulated phosphate rock treatments had significantly higher Cd concentrations in clover compared with single superphosphate at 4 sites. At the site where Hamrawein was tested, this treatment had significantly lower Cd concentrations in clover compared with both single superphosphate and North Carolina phosphate rock treatments.

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