Soil Carbon and Nitrogen Mineralization: Influence of Drying Temperature

Carbon and N mineralization in dried soils that are rewetted has been proposed as a rapid index of C and N mineralization potential and to reflect soil management, but further research is needed on effects of soil type and drying temperature for this approach. The objective of this study was to determine the effect of maintaining soil field moisture or drying soil at 40, 60, or 100degreesC followed by rewetting and a 3-d incubation on C and N mineralization across diverse soil types. Strong correlations between C mineralized in 24 d from field moist soils vs. C mineralized in 24 h from soils dried at 40 or 60degreesC were observed. Carbon mineralization values for 24 vs. 3 d resulted in nearly linear relationships for all drying treatments. Nitrogen mineralization in 24 d from moist vs. dried at 40 or 60degreesC and rewetted soils were also highly correlated with field moist N mineralization. The drying and rewetting pre-incubation of soil followed by a 3-d incubation was shown to be a useful indicator of longer-term (24 d) C mineralization potential. Nitrogen mineralization potential may also be obtained after drying/rewetting at 40 or 60degreesC without the need for keeping soil in a continuously field-moist state.