TY - JOUR T1 - Soil water in small drainages farmed with no-tillage and inversion tillage in northeastern Oregon JF - Journal of Soil and Water Conservation SP - 503 LP - 511 DO - 10.2489/jswc.71.6.503 VL - 71 IS - 6 AU - J.D. Williams AU - D.S. Robertson Y1 - 2016/11/01 UR - http://www.jswconline.org/content/71/6/503.abstract N2 - Crop productivity in the semiarid inland Pacific Northwest, United States, is dependent on the capture and storage of precipitation as soil water. To maximize soil water in this region, the conventional crop strategy is a two-year cropping system in which winter wheat (Triticum aestivum L.) is grown after a 14 month fallow period. This system is popular in the intermediate precipitation zone (300 to 450 mm [12 to 18 in]) in northeastern Oregon because of its history of producing reliable yields under highly variable precipitation. Adopting no-tillage and increasing the types of crops and frequency with which they are grown has the potential to improve soil quality and crop productivity. Water is the primary limiting factor in this region. Evaluating how increased cropping intensity and no-tillage affect the soil water regime is key to understanding the performance of these practices. Crops were grown in two small, upland drainages using inversion tillage or no-tillage. The inversion tillage drainage was in a two-year winter wheat–fallow rotation (Wf-F), from 2001 through 2004. From 2005 through 2008, it was divided in two parts with Wf-F in one half and annual cropping in the second half for adaptive management where the following were grown: recropped wheat (Wr), volunteer wheat (Wv), and wheat recropped after volunteer wheat Ww. The no-tillage drainage was divided into four roughly equal areas and farmed in a four-year rotation, which was completed twice in eight years (2001 to 2008). The four phases of the rotation were chemical fallow–winter wheat–spring pea (Cicer arietinum L. or Pisum sativum L.)–winter wheat (CF-Wcf-SP-Wsp). Mean crop yield was not significantly different between inversion tillage (2.98 ± 0.30 Mg ha−1 [1.33 ± 0.14 tn ac−1]) and no-tillage (3.14 ± 0.29 Mg ha−1 [1.40 ± 0.13 tn ac−1]). Crop yield in each rotation phase was significantly different (p ≤ 0.05) in the following ranked groups: Wcf ~ Wf ~ Ww > Wsp ~ Wr > Wv > SP. Contrary to this expectation, precipitation use efficiency (PUE) was significantly greater in the inversion tillage (0.019 ± 0.002 Mg ha−1 mm−1 [7.0 ± 0.6 bu ac−1 in−1]) than in the no-tillage (0.015 ± 0.001 Mg ha−1 mm−1 [5.5 ± 0.5 bu ac−1 in−1]) drainage. However, PUE among phases within each system differed significantly in the following ranked largest to smallest order: Wf ~ Wcf, Ww ~ Wsp ~ Wr ~ Wv, and SP. There was significantly more available water at the 30 cm (1 ft) depth in Wcf before fall planting than in the Wf. Early attempts at adopting no-tillage in northeastern Oregon were unsuccessful, generally attributed to poor soil water conditions, particularly near the surface. Based on crop yields reported here, it appears that more recent no-tillage technology and management of crop residue has alleviated this concern. A wider variety of alternative spring crops is needed to more thoroughly evaluate and compare PUE in intensified cropping systems to the traditional two-year winter wheat/fallow system practiced in the intermediate precipitation zone in northeastern Oregon. ER -