Developing Sustainable and Profitable Cropping Systems for North-Central Oregon.

The conventional winter wheat-summer fallow (WW-SF), the predominant cropping system in the inland Pacific Northwest (PNW), has been shown to deplete soil organic carbon and increase soil erosion. This research evaluates alternative direct seeded cropping systems (DS) designed to reduce these negative impacts on the soil and environment. In this long-term experiment, initiated in 2003-04 crop year, WW-SF, is compared to annual winter wheat (WW-WW), annual spring wheat (SW-SW), annual spring barley (SB-SB), winter wheat-chemical fallow (WW-CF), winter wheat-winter pea rotation (WW-WP), and winter wheat-spring barley-chemical fallow rotation (WW-SB-CF), all under direct seeding. As in the previous years, data on grain yield, diseases, weeds, microbial biomass, soil moisture, and crop residue cover were collected. Grain Yield: Based on the 7-yr average (2004/05 to 2010-11 crop-years) (Table 6) there were no significant differences in grain yield between the 3-yr rotation and two fallow rotations. These yields were significantly higher than grain yields from annual crops. Of the annual crops, yields of annual spring barley and spring barley following winter wheat in the 3-year rotation were significantly higher than yields from annual winter wheat and annual spring wheat but not from winter wheat after winter peas. These results suggested that direct seeded systems, that tend to increase soil organic matter and maintain surface residues that prevent soil erosion, can replace the conventional tillage wheat fallow system that is prevalent in these low rainfall areas of North-Central Oregon and South-Central Washington without any detriment to grain yields. Diseases: Lowest population densities occurred in the annual spring barley and in certain phases of winter wheat-chemical fallow rotation and the 3-year rotation. Population densities were particularly high in the annual winter wheat, annual spring wheat and certain phases of the winter wheat-conventional fallow and winter wheat-winter pea rotations. Weeds: Downy brome infestations have been the major weed concern particularly in annual winter wheat, and 2-year crop rotations with alternate years of winter wheat. Economics: Based on Moro LTE, WW-CF represents a promising cropping system for both farmers’ bottom line and the environment in Sherman County and perhaps in similar regions. WW-CF also manages economic risk and smoothens seasonal machinery and labor demands. Trends suggest that glyphosate/diesel price ratio will continue to decline. This trend will further strengthen advantage of WW-CF.