ARS | Publication request: WINTER WHEAT RESPONSES TO NITROGEN FERTILIZATION IN A DIRECT-SEED, SUMMER-FALLOW MANAGEMENT SYSTEM

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 20, 2005
Publication Date: November 6, 2005
Citation: Albrecht, S.L., Long, D.S. 2005. Winter wheat responses to nitrogen fertilization in a direct-seed, summer-fallow management system. Agronomy Abstracts. Agronomy Society of America. CD ROM.

Technical Abstract: The silt loam soils of the Columbia Plateau contain little organic matter and are easily eroded. Conservation tillage may decrease erosion on these soils; however, little is known about how the application of a conservation management system, such as direct-seed, will affect wheat production. A field experiment, utilizing direct-seed, summer-fallow management, was conducted from 1998 through 2004 at the Pendleton Experiment Station to study effects of tillage and of nitrogen (N) fertilization rates on winter wheat (Triticum aestivum L.) yields and soil properties. Wheat was grown without tillage (direct-seed) with fertilizer N rates of 0, 45, 90, 134, and 179 kg ha^-1. Conventional tillage (plow and rod-weeding) plots with fertilizer N rates of 0 and 179 kg ha^-1 were established for comparison. Tillage, N fertilization, and precipitation all affected wheat yield. Based on the 7-year averages from 1998 to 2004, yields of wheat with no fertilizer N were 570 g kg^-1 higher under conventional till than under direct-seed. However, wheat yields at the 134 kg ha^-1 N fertilization rate produced only 70 g kg^-1 higher yields with conventional tillage over 7 years. In direct-seed, 179 kg N ha^-1 had the greatest grain yields. The 7-year average yield for plots with a more recent transition into direct-seed was 6.12 Mg ha^-1, whereas the longer-established plots, begun 16 years earlier, yielded 5.85 Mg ha^-1. After conversion from a conventional system to a direct-seed management system, grain yields, although slightly lower than in a conventionally tilled system, did not decrease over time. Grain yields from direct-seed plots with adequate fertilizer N were 950 g kg^-1 of yields from conventionally managed plots with equivalent N levels.