Submitted to: Nitrogen Fixation International Congress
Publication Type: Abstract Only
Publication Acceptance Date: October 18, 2001
Publication Date: October 18, 2001
Citation: OLNESS, A.E., ARCHER, D.W. FACTORS AFFECTING MICROBIAL FORMATION OF NITRATE-N IN SOIL AND THEIR EFFECT ON FERTILIZER-N USE EFFICIENCY. NITROGEN FIXATION INTERNATIONAL CONGRESS. 2001. ABSTRACT P. 37. Technical Abstract: Mineralization of soil organic matter is governed by predictable factors with nitrate-N as the end product. Crop production interrupts the natural balance, accelerates mineralization of N, and elevates levels of nitrate-N in soil. Six factors determine nitrate-N levels in soils. These are: soil- clay content, bulk density, organic matter content, pH, temperature and rainfall. Maximal rates of N mineralization require an optimal level of ai filled pore space. Optimal air filled pore space depends on soil clay content, soil organic matter content, soil bulk density and rainfall. Pore space is partitioned into water filled and air space. A maximal rate of nitrate formation occurs at a pH of 6.7 and rather modest mineralization rates at pH 5.0 and pH 8.0. When the components are combined in a computer program, predictions of the soil nitrate-N concentrations with a relative precision of 1 to 2 micro g N/g of soil are obtained. Predicting mineralization in this manner allows optimal side-dress N applications to be determined for site-specific soil and weather conditions.