The Olsen-P test is used in Denmark as a standard analysis to determine available phosphorus (P) in the soil, and guidelines for P application are also based on it. However, in recent years, it has been found that this test is not always reliable for assessing P requirements, as several studies have shown yield increases in cereals that received P despite high expected P levels in the soil. The P-CaCl? test has been assessed through trials as more accurate than the Olsen-P test in certain areas of Denmark with naturally high levels of oxalate-extractable aluminum in the soil. Additionally, the method is expected to be more reliable on soils with low pH values. P-CaCl? is a soil test in which soil is shaken with the chemical calcium chloride (CaCl?), and the extracted P content is then measured. The same principle is used in the Olsen-P test with sodium bicarbonate, which also extracts the aluminium bound P. In both cases, the extracted amount is assumed to reflect the plant-available P in the soil. The method can be used as a supplementary test for soils where the Olsen-P test is not reliable, providing farmers with a more accurate assessment of the actual P requirement in the field.