Phosphorus extraction by selected methods in alkaline and calcareous soils after mono-ammonium phosphate application at different rates. 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: 60
• Page End: 69
• Publication Date: 2021-01-01
• Subjects: extraction methods -- irrigated soil -- phosphate reactions -- phosphorus requirements -- soil solution; Plant-soil relationships -- South Africa -- Periodicals; Plant-soil relationships -- Periodicals; Agronomy -- South Africa -- Periodicals; Soil science -- Periodicals; Botany -- Environmental aspects -- Periodicals; 630
• DOI: 10.1080/02571862.2020.1845828
• Languages: English
• ISSNs: 0257-1862

Abstract

Abstract : Little research has been done on extractable phosphorus (P) in alkaline and calcareous irrigated soils of South Africa. This study aimed to quantify extractable P by selected methods in these soils after application of mono-ammonium phosphate (MAP) at different rates. Six soils with a pH of 7.1 to 8.2 that contained 0.6–12.4% CaCO3 were incubated for two months after application of MAP at levels equivalent to 0, 16.8, 33.6, 50.4, 67.2, 84.0 or 100.8 kg P ha −1 . After incubation, soil P was extracted with the Olsen, Bray 1, Mehlich 3 and Ambic 1 methods. The most soil P was extracted with the Mehlich 3 method, and the least soil P was extracted with either the Bray 1 or Olsen methods, regardless of the MAP application rate. The differences in P extracted by the methods were attributed to the chemical composition of the extractants and the soil properties. Olsen and to a lesser extent Ambic 1 were the most reliable methods for establishing the amount of P required to raise the P status of the alkaline and calcareous soils. Future research should focus on establishing specific threshold values for soil and crop combinations with the Olsen method.