Comparison of Laboratory Methods and an In Situ Method for Estimating Nitrogen Mineralization in an Irrigated Silt-Loam Soil

Authors

Brian J. Wienhold, Soil and Water Conservation Research Unit, USDA-ARSFollow

Document Type

Article

Date of this Version

9-7-2007

Comments

Published in Communications in Soil Science and Plant Analysis, 38: 1721–1732, 2007.

Abstract

Nitrogen (N) mineralization makes a considerable contribution to crop-available N and is difficult to estimate. Reliable methods for measuring N mineralization are needed to produce data sets for developing N-mineralization models, as a component in fertilizer recommendation algorithms, and to assess the effect of management practices on N mineralization. Numerous methods are available for estimating N mineralization. Laboratory methods are relatively easy but may not reflect conditions in the field, and field methods are usually labor-intensive. A study was conducted to compare N-mineralization estimates using anaerobic and aerobic laboratory methods and an in situ field method for the 0- to 15-cm depth of a silt loam soil under irrigated corn (Zea mays L.). Mineralization estimates were also compared to N mineralization based on crop N content. Estimates of N mineralization were 101 kg ha^-1 for the anaerobic laboratory method, 284 kg ha^-1 for the aerobic laboratory method, and 134 kg ha^-1 for the in situ field method. The in situ field method provided a reasonable estimate of N mineralization (0 to 15 cm) when compared to the estimate of mineralized N (root zone) based on crop N content (215 kg ha^-1). The in situ field method can be used to measure N mineralization during the growing season and for comparing N mineralization among management practices.