The role of soil pH in the dissolution of phosphate rock fertilizers

Kanabo, I. A. K.; Gilkes, R. J.

doi:10.1007/bf01048916

Cited by 76 publications

(37 citation statements)

References 12 publications

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“…The depression of APR dissolution by lime was very clearly reflected by APR-RRo /oP (Table 4). This effect has been noted before for other PRs (Mackay & Syers 1986;Kanabo & Gilkes 1987;Robinson & Syers 1991), and attributed as much to an increase in soil Ca as the increase in pH caused by the lime application.…”

Section: Aisupporting

confidence: 77%

Effects and interactions of P fertiliser forms and rates of lime on a clover/ryegrass sward

Smith

Sinclair

1998

New Zealand Journal of Agricultural Research

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Triple superphosphate (TSP), Arad phosphate rock (APR), and "Longlife" superphosphate (LL) were compared for their effectiveness as P fertilisers on a ryegrass/clover sward in New Zealand to which lime had been applied at 0, 1.25, 2.5, and 51 ha -1 . The P fertilisers were applied annually for five (LL) or six (TSP and APR) years at 24 kg P ha -1 yr -1 ; there was also a nil P control. The trial design was a factorial of four P treatments × four lime treatments. DM yield responses were initially negligible but increased to a maximum of 27% by Year 5. Mean response to P fertiliser was 5% in spring and 16% in summer and autumn. There were significant DM responses to TSP and LL from Year 3 onwards and to APR from Year 4 onwards. Over the final three years, TSP and LL yielded significantly more DM than APR, but there was no significant difference in DM yield between TSP and LL. Herbage %P, herbage P uptake, and soil Olsen P were much more sensitive discriminators between P fertilisers than was DM production and showed significant differences between all fertilisers throughout most of the experiment, with the ranking of effectiveness being TSP>LL>APR>nil P. All measurements showed APR to be a relatively ineffective P fertiliser, giving only 41% of the response to TSP in Year 6 when averaged over all lime treatments. Herbage chemical analysis showed effectiveness of APR to be markedly reduced by 2.5 and 51 ha -1 lime. Calculations based on residual *Dr A. G. Sinclair died on 2 December 1996 while this paper was in preparation. A97007 Received 3 February 1997; accepted 10 October 1997PR in soil at the end of the experiment indicated that dissolution rates of APR with nil, 1.25, 2.5, and 5 t ha -1 lime were 23%, 20%, 7%, and 9% per year, respectively. The slow dissolution of APR was attributed to its relatively low reactivity as measured by solubility in formic acid. The PR content of LL (North Carolina PR) also proved very ineffective, with an average dissolution rate of 13% per year which was unaffected by lime application rate. It is suggested that granulation of LL depressed dissolution of its PR component. Lime at 5 t ha -1 raised soil pH from 5.6 to 6.5 one year after application, with intermediate rates having a pro rata effect. Soil pH subsequently declined, but with considerable year-to-year fluctuations, at rates proportional to the lime application rate. There were no positive DM responses to lime but there were significant depressions in Years 5 and 6. Lime reduced herbage %P in APR treatments only. Lime significantly reduced Olsen P in control and all fertiliser treatments throughout the experiment, but only with APR was there an associated reduction in herbage %P.

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Section: Aisupporting

confidence: 77%

Effects and interactions of P fertiliser forms and rates of lime on a clover/ryegrass sward

Smith

Sinclair

1998

New Zealand Journal of Agricultural Research

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“…1 apparently indicate that the mean pH determined the extent of rock phosphate dissolution. But it has been shown that the supply of protons, which depends on both pH and titratable acidity, determines the extent of rock phosphate solubilization rather than pH alone (15).…”

Section: Discussionmentioning

confidence: 99%

Solubilization of rock phosphate by Rhizobium and Bradyrhizobium.

Halder¹,

Mishra²,

Bhattacharyya

et al. 1990

J. Gen. Appl. Microbiol.

209

111

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The potential of strains of Rhizobium and Bradyrhizobium to solubilize rock phosphate was evaluated in vitro. Almost all organisms tested effectively solubilized rock phosphate and lowered the medium pH. The presence or absence of (NH4)2SO4 made little difference in the solubilization of rock phosphate. Among the strains, Rhizobium leguminosarum biovar viceae BICC635 was the most effective solubilizer. Maximum solubilization of phosphate and acid production was achieved after 3 days of incubation. The strain produced 2-ketogluconic acid in the culture medium, the primary cause of rock phosphate solubilization. Increasing the phosphate status of the medium had little effect on the extent of dissolution of Purulia rock phosphate. Adding calcium as CaCl2, CaCO3 and Ca(OH)2 reduced the phosphate solubilization from phosphate rocks. The results indicated that pH, per se, is of less importance in phosphate solubilization. EDTA increased the extent of rock phosphate solubilization, possibly by chelation of the calcium ions that the solubilization produced.

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“…The growth of the trees relies on the root capacity to use natural soil resources such as mineral P. Among the factors governing P dissolution, rhizosphere pH modifications and organic anion release are thought to be the most important [9]. Medium acidification can dramatically increase the dissolution of apatites or natural phosphates in the plant rhizosphere [6,10,11,15,16,20,24,30]. In plants, nitrogen supply is a key factor for rhizosphere pH, as a supply of NH 4 + will result in acidification, whereas NO 3 -will result in alkalisation of the medium [21].…”

Section: Introductionmentioning

confidence: 99%

Quantification of oxalate ions and protons released by ectomycorrhizal fungi in rhizosphere soil

Casarin¹,

Plassard

Souche

et al. 2003

Agronomie

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-This paper deals with the study of proton and oxalate release by two ectomycorrhizal fungi, Hebeloma cylindrosporum and Rhizopogon roseolus, grown alone or in association with Pinus pinaster and supplied with nitrate. An original culture device made it possible to observe the growth of the ectomycorrhizal roots and to measure pH and oxalate content at different levels: roots, ectomycorrhizae, external hyphae and rhizosphere soil. The results showed differences between the two species grown in vitro. These differences were strictly maintained in association with the plant. R. roseolus strongly acidified the rhizosphere and released oxalate. This oxalate excretion was enhanced by CaCO 3 in the soil. A strong correlation appeared between pH and oxalate contents in rhizosphere soil, indicating that oxalate ions and protons were released simultaneously. H. cylindrosporum did not release these ions and tended to alkalinise rhizosphere soil. Such chemicals, released by R. roseolus, could contribute to the mobilisation of P from soil.

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The role of soil pH in the dissolution of phosphate rock fertilizers

Cited by 76 publications

References 12 publications

Effects and interactions of P fertiliser forms and rates of lime on a clover/ryegrass sward

Effects and interactions of P fertiliser forms and rates of lime on a clover/ryegrass sward

Solubilization of rock phosphate by Rhizobium and Bradyrhizobium.

Quantification of oxalate ions and protons released by ectomycorrhizal fungi in rhizosphere soil

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