Leaching Methods Can Underestimate Mineralization Potential of Soils |
| |
| Authors: | Richard L Mulvaney Rafael Otto Kelsey L Griesheim Kai Su Paulo Cesar Ocheuze Trivelin |
| |
| Institution: | 1. Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, Illinois, USAmulvaney@illinois.edu;3. Department of Soil Science, College of Agriculture “Luiz de Queiroz”, University of S?o Paulo, Piracicaba, S?o Paulo, Brazil;4. Department of Crop Sciences, University of Illinois, Urbana, Illinois, USA;5. Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, China;6. Laboratory of Stable Isotopes, Center for Nuclear Energy in Agriculture, University of S?o Paulo, Piracicaba, S?o Paulo, Brazil |
| |
| Abstract: | Aerobic incubations to estimate net nitrogen (N) mineralization typically involve periodic leaching of soil with 0.01 M calcium chloride (CaCl2), so as to remove mineral N that would otherwise be subject to immobilization. A study was conducted to evaluate the accuracy of leaching for analysis of exchangeable ammonium (NH4+)-N and nitrate + nitrite (NO3?+ NO2–)-N, relative to conventional extractions using 2 M potassium chloride (KCl). Ten air-dried soils were used, five each from Illinois and Brazil, that had been amended with NH4+-N (1 g kg?1) and NO3–-N (0.6 g kg?1). Both methods were in good agreement for inorganic N analysis of the Brazilian Oxisols, whereas leaching was significantly lower by 12–48% in recovering exchangeable NH4+-N from Illinois Alfisols, Mollisols, and Histosols. The potential for underestimating net N mineralization was confirmed by a 12-wk incubation experiment showing 9–86% of mineral N recoveries from three temperate soils as exchangeable NH4+. |
| |
| Keywords: | Biological N availability index mineral N production net mineralization N fertilizer requirement soil incubation |
|
|
