A comparison of the results of phosphorus analyses of alkaline and calcareous soils amongst South African laboratories. Issue 1 (1st January 2021)

• Record Type: Journal Article
• Authors: Venter, AE; du Preez, CC
• Is Part Of: South African journal of plant and soil. Volume 38:Issue 1(2021)
• Page Start: 70
• Page End: 76
• Publication Date: 2021-01-01
• Subjects: Ambic 1 -- Bray 1 -- irrigated soils -- Mehlich 3 -- Olsen -- phosphorus extractants; Plant-soil relationships -- South Africa -- Periodicals; Plant-soil relationships -- Periodicals; Agronomy -- South Africa -- Periodicals; Soil science -- Periodicals; Botany -- Environmental aspects -- Periodicals; 630
• DOI: 10.1080/02571862.2020.1845829
• Languages: English
• ISSNs: 0257-1862

Abstract

Abstract : Large areas of alkaline and calcareous soils are irrigated in South Africa. For these soils, proper fertilisation programs based on soil phoshorus (P) analyses are required. Little is known about P analyses of alkaline and calcareous soils. The study aimed to compare P analyses by three laboratories, each using Bray 1, Mehlich 3 and Olsen extraction methods. Six soils with a pH of 7.1 to 8.2 that contain 0.6 to 12.4% of CaCO3 were incubated for two months after application of mono-ammonium phosphate (MAP) at levels equivalent to 0, 16.8, 33.6, 50.4, 67.2, 84.0 and 100.8 kg P ha −1, subjected to several wetting and drying cycles. The P contents that were reported differed in many instances between the laboratories. The differences were sometimes of such an extent that it will influence P fertiliser programs significantly. This should be a concern for farmers and their advisors. This is probably inter alia due to the chemical composition of the extractants. An in-depth investigation into a larger number of laboratories' P analyses of alkaline and calcareous soils is warranted to confirm the results.