The use of 32P in screening effectiveness of rock phosphates in Malaysian soils

A.R. Zaharah, . and M. Ahmad Sahali, . and H.A.H. Sharifuddin, . (1994) The use of 32P in screening effectiveness of rock phosphates in Malaysian soils. [Proceedings Paper]

A pot study was conducted to evaluate the effectiveness of five phosphate rocks North Carolina Algerian Tunisian Christmas Island and Chinaagainst triple superphosphate on five soil series Lating Katong Rengam Bungor and Bukit Tuku with pH H2O values ranging from 4.7 to 7.56.Two kilograms of each soil were thoroughly mixed with 1.5 g labelled superphosphate.These soils were then mixed with the respective phosphate rocks or triple superphosphate at 400 mg P pot-1.Corn used as the test crop was allowed to grow for one month.Total P taken up and 32P activity present were determined.The amount of P taken up from the phosphate rocks and TSP tested were calculated using the isotope dilution formula.An incubation study using only the Bungor series soil was also carried out in the laboratory using all these P fertilizers at 0.4 mg P g-1 soil.The soils were sampled at 1 2 4 6 8 10 12 14 16 and 18 weeks after incubation.Soil pH exchangeable Ca and P extracted by Olsen and Bray-1 were determined.For all the five soils tested TSP gave the highest utilisation percentage ranging from 5.8 to 13.3.Among the phosphate rocks tested CIRP and CRP gave significantly lower percentage utilisation values compared to NCRP ARP and GRP.Utilisation of NCRP ARP and GRP were significantly affected by soil pH.CIRP and CRP utilisation remained unchanged.Extractable P and exchangeable Ca values from the incubation studies were highest in soil treated with TSP.NCRP ARP and GRP gave similar values while CIRP and CRP showed significantly lower values compared to the other three phosphate rocks and TSP.Thus both 32P and incubation studies were able to differentiate reactive and unreactive phosphate rocks.Laboratories equiped with radioactive protection facilities can use the 32P isotope dilution technique for screening phosphate rocks which require less time and less chemical analyses in order to arrive at the same conclusion.

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Abstract

A pot study was conducted to evaluate the effectiveness of five phosphate rocks North Carolina Algerian Tunisian Christmas Island and Chinaagainst triple superphosphate on five soil series Lating Katong Rengam Bungor and Bukit Tuku with pH H2O values ranging from 4.7 to 7.56.Two kilograms of each soil were thoroughly mixed with 1.5 g labelled superphosphate.These soils were then mixed with the respective phosphate rocks or triple superphosphate at 400 mg P pot-1.Corn used as the test crop was allowed to grow for one month.Total P taken up and 32P activity present were determined.The amount of P taken up from the phosphate rocks and TSP tested were calculated using the isotope dilution formula.An incubation study using only the Bungor series soil was also carried out in the laboratory using all these P fertilizers at 0.4 mg P g-1 soil.The soils were sampled at 1 2 4 6 8 10 12 14 16 and 18 weeks after incubation.Soil pH exchangeable Ca and P extracted by Olsen and Bray-1 were determined.For all the five soils tested TSP gave the highest utilisation percentage ranging from 5.8 to 13.3.Among the phosphate rocks tested CIRP and CRP gave significantly lower percentage utilisation values compared to NCRP ARP and GRP.Utilisation of NCRP ARP and GRP were significantly affected by soil pH.CIRP and CRP utilisation remained unchanged.Extractable P and exchangeable Ca values from the incubation studies were highest in soil treated with TSP.NCRP ARP and GRP gave similar values while CIRP and CRP showed significantly lower values compared to the other three phosphate rocks and TSP.Thus both 32P and incubation studies were able to differentiate reactive and unreactive phosphate rocks.Laboratories equiped with radioactive protection facilities can use the 32P isotope dilution technique for screening phosphate rocks which require less time and less chemical analyses in order to arrive at the same conclusion.

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Item Type:	Proceedings Paper
Additional Information:	2 ills. 7 tables 9 refs.
AGROVOC Term:	FERTILIZERS
AGROVOC Term:	SOIL FERTILITY
AGROVOC Term:	SOIL ORGANIC MATTER
AGROVOC Term:	FERTILIZER COMBINATIONS
AGROVOC Term:	MALAYSIA
Geographical Term:	MALAYSIA
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:27
URI:	http://webagris.upm.edu.my/id/eprint/16511

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