Determination of Soil Feature Effects on Plant-Available Phosphorus Extraction using Response Surface and Cate–Nelson Methodology

Abstract

In this study, four soil extraction methods (Olsen, Soltanpour, Mehlich 3, and water saturation) were used to identify optimal concentrations of phosphorus (P) required for plant growth. Olsen soil extraction for P was the most appropriate method for soil types of this study as the greatest correlation coefficient for soil-test P and with plant factors was achieved. The optimal amount of soil features (pH, organic carbon, lime, gypsum, and clay) determined by using response surface methodology (a new optimization method) were 7.49, 0.66, 41.82, 4.21, and 31.34, respectively. More soil P was extracted when the soil had optimal amounts of these features, showing each feature had a significant effect on extracted soil P. Furthermore, the graphical method of Cate–Nelson determined the optimal amounts of P using Olsen, Soltanpour, Mehlich 3, and saturation extract methods for wheat as 15, 6.5, 35, and 1.5 mg kg⁻¹ soil in nongypsic soils and 17, 3.5, 45, and 2.5 mg kg⁻¹ soil in gypsic soils.

Keywords:

• Calcareous soil
• gypsic soil
• Mehlich 3
• Olsen
• phosphorous extraction
• response surface methodology
• Soltanpour