| dc.description.abstract | Variable drying temperatures during soil sample preparation may result in different results of the same sample. This project was conducted to determine the effect of drying and drying temperature on the results of common soil test analytes. Twenty-seven different soil samples from major agricultural regions of the U.S. were obtained and prepared for this study. The samples were hand ground to pass 2 mm sieve and divided into 6 portions. One of the 6 portions was kept at field moist condition, and the other 5 portions were dried at 25, 45, 65, 85 and 105�C overnight. Soil pH, and concentrations of ammonium-N, nitrate-N, plant available K, P, Ca, Mg, S, Cu, Fe, Zn, Mn, B, organic C, and total N were determined using standard methods. In general, sample drying increased the concentration of most analytes compared with the field moist samples. The impact of drying temperatures on K concentrations was variable : some soils were increased, or decreased, but others were unchanged. The contents of Fe, B, Zn, Mn, NH4-N, and P, were increased by drying temperatures. The concentrations of Cu and Mg, however, were not consistently affected by drying temperatures. In addition, the initial field moist soil test values affected how drying temperatures impacted on the concentrations of NO3-N, NH4-N, Ca, organic C, and total N. Soil pH was affected differently, half of the samples decreased while the other half did not change by drying or drying temperature significantly. It is important for laboratories to use a standardized sample drying temperature to accurately characterize soils and make fertilizer recommendations. | |
