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ARS Home » Pacific West Area » Pendleton, Oregon » Columbia Plateau Conservation Research Center » Research » Publications at this Location » Publication #168494
Title: LONG-TERM CROPPING SYSTEM EFFECTS ON SOIL NITROGEN

Author
item Albrecht, Stephan
item MACHADO, STEPHEN - OREGON STATE UNIV

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/29/2003
Publication Date: 11/6/2003
Citation: Albrecht, S.L., Machado, S. 2003. Long-term cropping system effects on soil nitrogen. Agronomy Abstracts. (CD-ROM). American Society of Agronomy, Madison, WI.

Interpretive Summary:

Technical Abstract: Long-term research can guide agricultural development by identifying the effects of management practices on agronomic performance and soil quality. Long-term experiments on crop rotation, tillage, residue management and fertilization were initiated at the Pendleton Experiment Station in 1931. Wheat grown following summer fallow has responded to N fertilizer applications since the mid 1930's. The amount of additional N required for optimum wheat yield has risen from about 17 kg N per ha in the 1940's to more than 100 kg N per ha today. Nitrogen fertilization rate for optimum wheat yield is directly proportional to growing season precipitation and soil depth. Nitrogen mineralized during the year increased with increasing N fertilization and with reduction in tillage intensity and cropping frequency; however, that amount of mineralization is small compared to the N requirements for greatest yields. Soil erosion has been low in our long-term studies, but over many years even minimal soil loss can have substantial impact on N levels. The major factors influencing changes in soil N, and organic C, were the frequency of summer fallow and the amount of crop residue left in the field.