The 0.01 M CaCl₂ universal extractant is known all over Europe since the 90’s. During my research, I exam the phosphorus content determined in 0.01 M CaCl₂ of the samples originated from the B 17 National Uniformed Long Term Fertilisation Trials in the experimental site Karcag, in the 40^th year of the experiment. Relationships between the CaCl2-P and the AL-P content of the soil, the average yields, and the phosphorus balance of the
2006/2007 year were studied. From the results of the study it was concluded as follows:
– Correlation was close (r=0.68-0.7) between the AL-P and CaCl₂-P. This is in accordance with the results of previous experiments in Hungary and other countries.
– My studies confirmed that the calcium-chloride method indicates well the deficiency and the surplus of plant available phosphorus. In case of different degrees of negative balance, the amount of CaCl₂ extractable phosphorus showed no changes, or decreased, and in case of positive balance it increased exponentially by the long-term effect of P rates.
– The 120 and 180 kg ha^-1 rates resulted in significant increases in the amount of CaCl₂-P according to the control and treatments that are not fertilized with phosphorus. The 60 kg ha^-1 rate didn’t result any increase as it didn’t meet the phosphorus requirement of winter wheat, and presumably the P-balance was negative in the earlier years as well.
– It can be stated that the 0.01 M CaCl₂ was able to assess the deficiency and the excess of phosphorus causing negative impacts on environment as well.