Glasshouse comparison of North Carolina phosphate rock, alkali-treated Christmas Island phosphate rock and single superphosphate as P fertilizers on an acidic soil

1992 ◽  
Vol 43 (7) ◽  
pp. 1667 ◽  
Author(s):  
MJ McLaughlin ◽  
PR Dann ◽  
TR James ◽  
DL Garden
Keyword(s):  
North Carolina ◽  
Phosphate Rock ◽  
Acidic Soil ◽  
Ammonium Citrate ◽  
Residual Value ◽  
Single Superphosphate ◽  
Christmas Island ◽  
Fertilizer Application Rate ◽  
Significant Difference ◽  
P Recycling

Three fertilizers were compared for their P release to pasture species growing on an acidic soil under glasshouse conditions. The fertilizers were a reactive apatitic phosphate rock (North Carolina, NCPR), a KOH-treated crandallite/millisite/goethite phosphate rock (Christmas Island C-grade ore, KC) and single superphosphate (SSP). Four successive crops were grown after an initial application of five rates of each fertilizer. The effect of P recycling on the yield responses to fertilizers was assessed in one set of treatments by replacing P removed in successive herbage harvests with P in sheep dung. NCPR and KC were not as effective as SSP for the first crop, and effectiveness decreased as fertilizer application rate increased. With subsequent crops (24) and for total dry matter production data (crops 1-4 combined) the relative effectiveness of NCPR depended on P recycling treatment. When P was removed at each harvest, NCPR was just as effective as SSP, but KC was less than one third as effective as SSP. When P was recycled after each harvest, NCPR was less effective than SSP, and KC was at best only one-third as effective as SSP. After three crops, the residual value of the three fertilizers was assessed against crop response to a fresh application of SSP. Residual value of all fertilizers was significantly increased by recycling P to the pots. KC had a significantly lower residual value than the other fertilizers, but there was no significant difference between the residual value of initially applied SSP and NCPR. Solubility of P in the SSP and KC fertilizers as measured by water and neutral ammonium citrate was well correlated with plant response to the fertilizers, while the performance of NCPR was underestimated by these methods.

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.

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.

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.

Causes for the reduced reactivity of phosphate rock residues in partially acidulated phosphate rocks

Soil Research ◽  
1994 ◽  
Vol 32 (1) ◽  
pp. 95 ◽  
Author(s):  
HJ Di ◽  
LM Condron ◽  
AS Campbell ◽  
KM Goh ◽  
IS Cornforth
Keyword(s):  
North Carolina ◽  
Phosphate Rock ◽  
Water Soluble ◽  
Partially Acidulated Phosphate Rock ◽  
Ammonium Citrate ◽  
Insoluble Residue ◽  
Partial Acidulation ◽  
C:P Ratio ◽  
Fluoride Complexes ◽  
Acid Solubility

The agronomic effectiveness of partially acidulated phosphate rock (PAPR) fertilizers depends on the proportion of water soluble P present and the long-term release of P from the unacidulated residual phosphate rock (water-insoluble residue) in the soil environment. The relative reactivity of water-insoluble residues in a range of partially acidulated phosphate rock (PAPR) fertilizers was assessed according to chemical solubility, and was found to be lower than the corresponding original PRs. Two causes were identified for the reduced formic acid solubility of water-insoluble residues: (i) some preferential dissolution of more reactive apatite components (i.e. higher carbonate substituted apatite) during partial acidulation as indicated by reductions in the molar apatite C:P ratio of the residual PRs compared with the corresponding original PRs, and (ii) acid-insoluble metal (Fe-Al-Mg)phosphate and/or fluoride complexes formed on the surface of residual PRs during partial acidulation with commercial-grade phosphoric acid, which were partially soluble in alkaline ammonium citrate. These two mechanisms accounted for most of the solubility differences observed for 'medium' reactive PRs (Khouribga, Arad), compared with only half for more reactive PRs (North Carolina, Gafsa). The conclusion from this study is that partial acidulation may not be an ideal method for the manufacture of fertilizers containing fast and slow release (i.e. PR) components, particularly when highly reactive PRs such as North Carolina are used.

Kinetics of Phosphate Rock Dissolution in Acidic Soil Amended with Liming Materials and Cellulose

1996 ◽  
Vol 60 (6) ◽  
pp. 1589-1595 ◽  
Author(s):  
Z. L. He ◽  
V. C. Baligar ◽  
K. D. Ritchey ◽  
D. C. Martens ◽  
W. D. Kemper
Keyword(s):  
Phosphate Rock ◽  
Acidic Soil ◽  
Phosphate Rock Dissolution ◽  
Kinetics Of

An Investigation into the Impact of Environmental Education Certification on Perceptions of Personal Teaching Efficacy

2017 ◽  
Vol 22 (2) ◽  
pp. 5-17
Author(s):  
Mandy Harrison ◽  
Lisa Gross ◽  
Jennifer McGee
Keyword(s):  
North Carolina ◽  
Environmental Education ◽  
Self Efficacy ◽  
Teaching Efficacy ◽  
School Teachers ◽  
The North ◽  
Significant Difference ◽  
Personal Teaching Efficacy ◽  
Environmental Educators ◽  
The Impact

The purpose of this study is to examine how participation in the North Carolina Environmental Educator (NCEE) program influences the individual's perceived self-efficacy. Specifically, this study examines the impact of NCEE certification on participants’ perceived personal teaching self-efficacy. This study compared personal teaching efficacy scores of certified environmental educators, non-certified environmental educators, and licensed schoolteachers. The study found significant differences in teaching efficacy between certified and non-certified environmental educators, as well as certified environmental educators and licensed school teachers. In addition, the study found no significant difference in efficacy scores between NCEE certified licensed school teachers and NCEE certified environmental educators. Results of this study indicate a link between environmental education certification and higher personal teaching efficacy.

Kinetics of Phosphate Rock Dissolution in Acidic Soil Amended with Liming Materials and Cellulose

1996 ◽  
Vol 60 (5) ◽  
pp. 1589-1595 ◽  
Author(s):  
Z. L. He ◽  
V. C. Baligar ◽  
K. D. Ritchey ◽  
D. C. Martens ◽  
W. D. Kemper
Keyword(s):  
Phosphate Rock ◽  
Acidic Soil ◽  
Phosphate Rock Dissolution ◽  
Kinetics Of

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.

scholarly journals Field evaluation of water or citrate soluble phosphorus in modified phosphate rocks for soybean

2001 ◽  
Vol 58 (1) ◽  
pp. 165-170 ◽  
Author(s):  
Luís Ignácio Prochnow ◽  
José Francisco da Cunha ◽  
Ariel Francisco Candiotti Ventimiglia
Keyword(s):  
Field Evaluation ◽  
Water Soluble ◽  
Ammonium Citrate ◽  
Low Grade ◽  
Triple Superphosphate ◽  
Single Superphosphate ◽  
Standard Source ◽  
Extractable P ◽  
P Fertilizers ◽  
P Sources

Ten P fertilizers were collected (commercial fertilizers) or synthesized (experimental sources) in order to obtain single superphosphates varying in water and citrate solubility. A standard source of P was also produced by crystallization of the water-soluble fraction of a triple superphosphate. Eleven P sources were band applied to a medium textured Xanthic Hapludox, in Bahia, Brazil (low content of resin-extractable P) at a rate of 80 kg ha-1 of NAC + H2O (neutral ammonium citrate plus water) soluble P2O5, with soybean as the crop which was grown to maturity. A check plot (control) was included in the study. Three of the P sources [single superphosphate produced from Araxa phosphate rock (PR), low-grade single superphosphate produced from Lagamar PR and the standard source of P] were also applied at rates to provide 40 and 120 kg ha-1 of NAC + H2O soluble P2O5. Yield of soybean was evaluated by analysis of variance with mean comparison performed utilizing LSD lines, considering the P sources applied at a rate of 80 kg ha-1 of P2O5 + control. Regression procedures were used to study the relation between yield of soybean and rates of P2O5. The fertilizers tested performed equally well as a source of P for soybean. The level of water-soluble P did not influence fertilizer performance.

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