No‐Tillage Cropping Systems Can Replace Traditional Summer Fallow in North‐Central Oregon

Abstract

Winter wheat (Triticum aestivum L.)–summer fallow (WW–SF) using conventional tillage (CT), the predominant cropping system in eastern Oregon, has increased soil erosion and depleted soil organic carbon (SOC). This research evaluates no‐tillage (NT) systems designed to reduce these negative impacts on soil. In this long‐term experiment (2004–2010), WW–SF using CT was compared with annual winter wheat (WW–WW), annual spring wheat (SW–SW), annual spring barley (Hordeum vulgare L.) (SB–SB), winter wheat–chemical fallow (WW–CF), winter wheat–winter pea (Pisum sativum L.) (WW–WP), and winter wheat–spring barley–chemical fallow rotation (WW–SB–CF), using NT. Measurements included, phenology, plant population, grain yield and yield components, residues, SOC, soil moisture, and precipitation. Water‐use efficiency (WUE) was derived from precipitation and yield data. Under annual cropping, WW–WP and SB–SB produced higher yields than WW–WW and SW–SW. Grain yields in rotations with fallow (WW–SF, WW–CF, and WW–SB–CF) were not significantly different. On an annual basis, SB–SB and WW‐WP produced the highest and lowest yields, respectively. The WUEs of fallow rotations, SB–SB, and SW–SW, were not different but were higher than WUEs of WW–WP and WW–WW. Residue cover and SOC were highest under annual cropping systems and lowest following peas in WW–WP and SF in WW–SF. We conclude that rotations with fallow using NT (WW–CF and WW–SB–CF) can replace the traditional WW–SF system without yield penalty.