How Air-Drying Affects DGT P Results in Calcareous Soils
Yulin Zhang 1  
,   Yanli Wang 1  
,   Yaru Tan 1  
,   Limin Li 1  
,   Xudong Wang 1  
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College of Resources and Environment, Northwest A and F University, Yangling, P.R. China
Xudong Wang   

Northwest A&F University, 715, College of Resources and Environment, 3 Taicheng Road, 712100 Yangling, China
Submission date: 2017-12-16
Final revision date: 2018-02-01
Acceptance date: 2018-03-04
Online publication date: 2018-11-08
Publication date: 2019-01-28
Pol. J. Environ. Stud. 2019;28(3):1507–1515
Diffusive gradients in thin films (DGT) technology has been increasingly proved to be a promising tool for accurately predicting plant-available phosphorus (P) in soil using air-dried samples. However, the effects of the air-drying process on DGT-measured P are unknown compared to those of using moist samples in which plant roots survive throughout a growing season. We investigated the differences between the Olsen P and DGT P values in 58 air-dried and moist soil samples. The results showed that the discrepancy in the DGT P values between air-dried and moist samples increased with an increase in the organic P concentration in soils. It was presumed that the air-drying process converted some easily mineralized organic P into its inorganic form, thereby allowing it to be measured by the DGT method. The DGT P values in moist samples can be calculated from the values obtained in air-dried samples using the following equation: . However, the Olsen P values were highly correlated (R2 = 0.95) when using air-dried and moist samples, although significant differences were observed. We concluded that the effects of air-drying on predicting soil available P using the Olsen P method can be neglected due to the high correlation relationship. The availability of easily mineralized organic P needs to be further explored.