Submitted to: World Congress of Soil Science
Publication Type: Abstract Only
Publication Acceptance Date: 6/9/2014
Publication Date: N/A
Technical Abstract: A biologically based tool to improve nitrogen (N) management in cereal crops is currently lacking from soil testing programs, but very much needed to optimize N fertilizer inputs to be able apply enough N fertilizer to achieve high production and avoid excess application that is damaging to the environment. We are developing such a tool based on growing confidence from previous research that shows strong relationships between the short-term flush of carbon dioxide (CO2) following rewetting of dried soil and several other soil biological properties, including short-term net N mineralization and soil microbial biomass. Soil microbial biomass is an active part of soil organic matter that plays a key role in the decomposition of organic materials, nutrient cycling, and formation of soil structure. Across a number of soils with a wide range of soil organic matter concentrations, the flush of CO2 following rewetting of dried soil has been closely related to (1) the flush of CO2 following fumigation with chloroform, (2) potential C mineralization, and (3) potential N mineralization. We describe the framework for a practical decision support system to improve N fertilizer recommendations for corn and other cereals. The short-term flush of CO2 following rewetting of dried soil predicts N mineralized from soil organic matter during the growing season and from rapidly decomposable substrates (e.g. cover crops, previous crop residues, manure additions, etc.), but may need adjustment based on variations in the soluble C-to-N ratio that can predict N immobilization. Applicable results have been obtained with a large number of different soil types. Development of this simple, rapid, and robust biologically based indicator of potential N mineralization will help farmers, consultants, soil testing facilities, and scientists better promote sustainable agricultural production.