X-Ray Investigation of Carbonate Apatites

Smith, Jesse; Lehr, James R.

doi:10.1021/jf60146a004

Cited by 74 publications

(32 citation statements)

References 7 publications

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“…The compositions of carbonate apatite in various RPs are highly correlated with a-axis spacing which is determined through X-ray diffraction analysis (XRD) of RP (Smith and Lehr, 1966;McClellan and Gremillion, 1980). Specifically, the a-axis spacing is related with molar ratio CO 3 :PO 4 as follows:…”

Section: Theoretical Calculationsmentioning

confidence: 99%

Potentiality of Indian rock phosphate as liming material in acid soil

Basak

Biswas

2016

Geoderma

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Section: Theoretical Calculationsmentioning

confidence: 99%

Potentiality of Indian rock phosphate as liming material in acid soil

Basak

Biswas

2016

Geoderma

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“…The higher amount of Olsen P obtained from the application of TSP compared to MPR and BPR is ascribed to the higher solubility of TSP compared to the PRs whose dissolution is usually slow (Chien et al 1980). The higher amount of Olsen P obtained as a result of application of MPR compared to BPR can be attributed to differences in their solubility arising from varying extents of carbonate substitution in the PRs (Smith and Lehr 1966). BPR is a low carbonate-substituted variety of igneous origin with low reactivity in acids solvents, with a neutral ammonium acetate (NAC) solubility of 10% compared to 23% for MPR (McClellan 1991;van Kauwenbergh 1991).…”

Section: Exchangeable Aluminummentioning

confidence: 99%

Effect of organic and inorganic phosphorus sources on maize yields in an acid soil in western Kenya

Opala

Okalebo

Othieno

et al. 2009

Nutr Cycl Agroecosyst

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Maize production in western Kenya is commonly limited by P deficiencies and aluminum phytotoxicity. Due to high costs of imported fertilizers and lime, focus is now shifting to solutions that utilize local resources. We tested the effect of three inorganic P sources i.e., triple superphosphate (TSP), Minjingu phosphate rock (MPR) and Busumbu phosphate rock (BPR), each applied in combination with two organic materials (OMs) i.e., farmyard manure (FYM) and Tithonia diversifolia green manure (tithonia), or with urea on soil chemical properties related to soil acidity, P availability and maize yields for three consecutive seasons in western Kenya. The OMs and inorganic P sources were applied to provide 20 and 40 kg P ha -1 respectively in their combination. Where urea was used, the inorganic P sources were applied at 60 kg P ha -1 . Maize did not respond to application of TSP, MPR or BPR with urea in the first two seasons. However, after three seasons, maize significantly responded to application of MPR with urea. FYM was more effective than tithonia in increasing the labile inorganic P pools but it gave lower maize yields than tithonia which was more effective in reducing the exchangeable Al. It appears that the ability of an OM to lower the exchangeable Al is more important in increasing maize yields than its ability to increase P availability. The effectiveness of the inorganic P sources in increasing maize yields followed the order of their effectiveness in increasing available P, i.e., TSP [ MPR [ BPR, once Al phytotoxicity was reduced by application of tithonia but the difference between TSP and MPR was not significant. The extra maize yield obtained by the additional 40 kg P ha -1 from the inorganic P sources was, however, in most cases not substantial enough to justify their use. Economic considerations may therefore favour the use of tithonia or FYM when applied alone at 20 kg P ha -1 than when combined with any of the inorganic P sources used in this study at a total P rate of 60 kg ha -1 .

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“…e North Carolina PR. f Nauru PR data fromSmith and Lehr (1966). was done on the same day as the fertilizers were applied in order to optimize plant competitiveness for P. Two or three maize seeds (variety TMV-2+145 for Nkundi and Sasanda and variety staha for Magadu and Mlingano) were sown. Thinning was carried out one week after emergence leaving one plant per hole giving 120 plants per plot.…”

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confidence: 99%

Hard Minjingu Phosphate Rock: an Alternative P Source for Maize Production on Acid Soils in Tanzania

Msolla

Semoka

Borggaard³

2005

Nutr Cycl Agroecosyst

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The phosphate rock (PR) deposit at Minjingu in northern Tanzania consists of two forms, locally called hard Minjingu phosphate rock, MPR (4.8 · 10 6 Mg with 10.6% P) and soft MPR (3.3 · 10 6 Mg with 13.3% P). Extensive chemical and instrumental analyses have shown that the two MPRs differ mainly in consistency, while their reactivities are comparable. Soft MPR in direct application has been extensively evaluated with good results under greenhouse and field conditions whereas hard MPR has only been tested in a greenhouse experiment. The agronomic value of directly applied hard MPR on maize growth was therefore tested under field conditions on four acidic soils low in available Ca and P at Magadu (Ultisol), Mlingano (Oxisol), Nkundi (Ultisol) and Sasanda (Andisol). The treatments tested were hard MPR, soft MPR, triple superphosphate (TSP) and a control. Each P source was applied at a rate of 80 kg ha À1 P at Magadu, Mlingano and Nkundi but 160 kg ha À1 P at Sasanda. Other nutrient deficiencies were corrected in each soil with appropriate fertilizers that were applied in all three years of experimentation. The soils gave significant positive responses to application of the three P sources but TSP application resulted in significantly higher P concentrations in leaves and grain yields than MPR addition in the first year. However, in the second and third years the performance of MPRs approached that of TSP and the relative agronomic effectiveness (RAE) of MPRs increased from 50 -70% in the first year to 80 -95% in year three. Moreover, crop performances on hard MPR-treated plots and soft MPR-treated plots were not significantly different. This important result suggests that hard MPR can replace soft MPR and even TSP on acidic soils low in available Ca and P. However, more testing is needed to ensure confident delineation of soils that respond to direct application of hard MPR from non-responding soils. The rather poor performance of MPR for the first year must also be improved.

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X-Ray Investigation of Carbonate Apatites

Cited by 74 publications

References 7 publications

Potentiality of Indian rock phosphate as liming material in acid soil

Potentiality of Indian rock phosphate as liming material in acid soil

Effect of organic and inorganic phosphorus sources on maize yields in an acid soil in western Kenya

Hard Minjingu Phosphate Rock: an Alternative P Source for Maize Production on Acid Soils in Tanzania

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