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United States Department of Agriculture

Agricultural Research Service

Title: Accounting for Seasonal Nitrogen Mineralization: a Review

Authors
item Vigil, Merle
item Eghball, B - UNIVERSITY OF NEBRASKA
item Cabrera, M - UNIVERSITY OF GEORGIA
item Jakubowski, B - COLORADO STATE UNIVERSITY
item Davis, J - COLORADO STATE UNIVERSITY

Submitted to: Journal of Soil and Water Conservation Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 2002
Publication Date: November 1, 2002
Citation: VIGIL, M.F., EGHBALL, B., CABRERA, M.L., JAKUBOWSKI, B.R., DAVIS, J.G. ACCOUNTING FOR SEASONAL NITROGEN MINERALIZATION: A REVIEW. JOURNAL OF SOIL AND WATER CONSERVATION SOCIETY. 2002. v. 94. p. 464-469.

Interpretive Summary: To accurately make fertilizer use decisions farmers need to know the amount and rate of N released from soil organic matter (SOM) during the growing season. Accurately predicting the amount of N made available for crop use by N mineralization (Nmin) of native soil organic matter (SOM) is difficult. Different soils, climate and management, all highly variable from one location to the next complicates the issue. Here we compiled seasonal estimates of Nmin from several field studies. In general, each specific data set reported a different incubation time. To compare data sets, all reported Nmin values were recalculated, based on a 20 week incubation period. Values of Nmin for a season, ranged between 0.4 and 152 kg N/ha (0.3 and 136 lb N/acre). The average amount of Nmin for all of these studies was 33 kg N/ha (29 lb N/acre). After recalculating all data to a 20 week incubation period, 42 % of the variability in 20 week Nmin amount could be explained by total N. Curve fitting of total-soil N, and o SOM content, on the seasonal Nmin amount indicates that neither SOM or total-N is a good indicator for predicting for the seasonal Nmin amount. Soil type and management as well as climate at the various locations obviously influenced the magnitude of the estimates. This summary supports the push for an accurate predictive simulation model for seasonal Nmin that is non site specific.

Technical Abstract: Accurately predicting the amount of N made available for crop use by N mineralization (Nmin) of native soil organic matter (SOM) is difficult. Different soils, climate and management, all highly variable from one location to the next complicates the issue. Here we compiled seasonal estimates of Nmin from several field studies. For a first cut, we only include data for native-SOM and do not include organic amended soils. In general, each specific data set reported a different incubation time. To compare data sets, all reported Nmin values were normalized to a 20 week incubation period. Values of Nmin for a season, range between 0.4 and 152 kgN/ha (0.3 and 136 lb N/acre). The average amount of Nmin for all of these studies was 33 kg N/ha (29 lb N/acre). A graph of Nmin for all of the data against SOM gives a negative relationship with a non significant R2 of 0.04. A similar fit of all of the data against total N is also of little value. After normalizing all data to a 20 week incubation period, and if all of the data collected from short incubations are eliminated from the data set (incubations that are less than 15 weeks) 42 % of the variability in 20 week Nmin amount can be explained by total N. Regression analysis of the total-soil N, and of SOM content, on the seasonal Nmin amount indicates that neither SOM or total-N is a good predictor for the seasonal Nmin amount Soil type and management as well as climate at the various locations obviously influences the magnitude of the estimates. More importantly, this summary supports the push for an accurate predictive simulation model for seasonal Nmin that is non site specific.

Last Modified: 12/28/2014
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