Wednesday, 9 November 2005
7

This presentation is part of: Tillage and Plant Nutrition

Nitrogen Mineralization in Soils under Conservation Tillage.

Sirio Wietholter, Harry H. Schomberg, Miguel L. Cabrera, Alan Franzluebbers, and Dwight S. Fisher.

Managing soil for agricultural production without tillage is considered sustainable and environmentally beneficial. In Brazil and in the USA the no-tillage system is used on over 20 Mha. Nitrogen fertilization is a major concern in no-tillage, for both economic and environmental reasons. Most fertility recommendation systems do not include specific soil parameters to determine the amount of N to be applied. A few recommendation systems include soil organic matter and/or soil nitrate. Our objective was to evaluate several methods of assessing N mineralization and determine how they could be used to parameterize currently available N simulation models. Forty-four soil samples from field plots under different tillage management systems located in various ecological regions of the southern USA were analyzed with chemical and biological procedures to predict N mineralization. Methods included: calcium hypochlorite oxidation, hot and cold 2 M KCl extraction, short-term anaerobic incubation, CO2 evolved during three days, soil microbial biomass, near infrared reflectance spectrophotometry, total C and N by dry combustion, and non-leached long-term aerobic incubation. Results from the different procedures and their correlation to potentially mineralizable N will be presented.

See more of Tillage and Plant Nutrition
See more of S04 Soil Fertility & Plant Nutrition

See more of The ASA-CSSA-SSSA International Annual Meetings (November 6-10, 2005)