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ARS Home » Pacific West Area » Pendleton, Oregon » Soil and Water Conservation Research » Research » Publications at this Location » Publication #321984

Research Project: Improved Soil Managment Practices for Tilled Summer Fallow in the Pacific Northwest

Location: Soil and Water Conservation Research

Title: Soil water in small drainages farmed with no-tillage and inversion tillage in northeastern Oregon

Author
item Williams, John
item Robertson, David - Dave

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2016
Publication Date: 11/1/2016
Citation: Williams, J.D., Robertson, D.S. 2016. Soil water in small drainages farmed with no-tillage and inversion tillage in northeastern Oregon. Journal of Soil and Water Conservation. 71(6):503-511.

Interpretive Summary: Crop productivity in the semi-arid inland Pacific Northwest (IPNW), USA 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 crop – fallow system in which winter wheat (W, Triticum aestivum L.) is grown after a 14 month fallow period. This system is popular in the intermediate precipitation zone in northeastern (NE) Oregon because of its history of producing reliable yields under highly variable seasonal and annual 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. Soil water was measured in a Walla Walla silt loam soil (coarse-silty, mixed, superactive, mesic Typic Haploxerolls). Crops were grown in two small watersheds using disturbance tillage (DT) or no-tillage (NT). The DT watershed was in a two-year wheat–fallow rotation (DTW) from 2001 through 2004, and then divided in two parts for adaptive management that included the two year rotation DTW and annual cropping from 2005 through 2008 [recropped wheat (WRW), volunteer wheat (RWVW), and wheat recropped after VW (VWW). The second watershed (NT) was divided into four equal areas in a four-year crop rotation with periods of chemical fallow (CF), winter wheat (W), pea [spring chickpea (Cicer arietinum L.,) or dry spring peas (Pisum sativum L.)] (SP). The rotation, in order, were WCF, CFW, WSP, SPW, in which each phase of the rotation was represented twice in eight years (2001 to 2008). Mean crop yield was not significantly different between the DT [2.98±0.30 Mg ha-1 (1.33±0.14 t ac-1)] and NT [3.14±0.29 Mg ha-1 (1.40±0.13 t ac-1)]. Crop yield in each rotation phase was significantly different (P = 0.05) in the following ranked groups: CFW~PFW~VWW > SPW~WRW > RWVW> WSP. In ranked groups of significance, water use efficiency (WUE) was largest in CFWW~PFWW~VWW, VWW~SPW~WRW~RWVW, and WSP. There was significantly more available water at the 30 cm (1ft) depth in WCF before fall planting than in the WWPF. Early attempts at adopting no-tillage in northeastern Oregon were unsuccessful, with much of the blame placed on poor soil water conditions, particularly near the surface. Based on crop yields and WUE results reported here, it appears that more recent no-till technology and management of crop residue has alleviated these concerns. Although this research did not address the economic aspects of adoption of these practices. We feel confident that no-tillage and increased cropping intensity are biologically and physically feasible in the intermediate precipitation zone of the NE Oregon.

Technical Abstract: Crop productivity in the semi-arid inland Pacific Northwest (IPNW), USA 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 crop – fallow system in which winter wheat (W, Triticum aestivum L.) is grown after a 14 month fallow period. This system is popular in the intermediate precipitation zone in northeastern (NE) Oregon because of its history of producing reliable yields under highly variable seasonal and annual 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. Soil water was measured in a Walla Walla silt loam soil (coarse-silty, mixed, superactive, mesic Typic Haploxerolls). Crops were grown in two small watersheds using disturbance tillage (DT) or no-tillage (NT). The DT watershed was in a two-year wheat–fallow rotation (DTW) from 2001 through 2004, and then divided in two parts for adaptive management that included the two year rotation DTW and annual cropping from 2005 through 2008 [recropped wheat (WRW), volunteer wheat (RWVW), and wheat recropped after VW (VWW). The second watershed (NT) was divided into four equal areas in a four-year crop rotation with periods of chemical fallow (CF), winter wheat (W), pea [spring chickpea (Cicer arietinum L.,) or dry spring peas (Pisum sativum L.)] (SP). The rotation, in order, were WCF, CFW, WSP, SPW, in which each phase of the rotation was represented twice in eight years (2001 to 2008). Mean crop yield was not significantly different between the DT [2.98±0.30 Mg ha-1 (1.33±0.14 t ac-1)] and NT [3.14±0.29 Mg ha-1 (1.40±0.13 t ac-1)]. Crop yield in each rotation phase was significantly different (P = 0.05) in the following ranked groups: CFW~PFW~VWW > SPW~WRW > RWVW> WSP. In ranked groups of significance, water use efficiency (WUE) was largest in CFWW~PFWW~VWW, VWW~SPW~WRW~RWVW, and WSP. There was significantly more available water at the 30 cm (1ft) depth in WCF before fall planting than in the WWPF. Early attempts at adopting no-tillage in northeastern Oregon were unsuccessful, with much of the blame placed on poor soil water conditions, particularly near the surface. Based on crop yields and WUE results reported here, it appears that more recent no-till technology and management of crop residue has alleviated these concerns. Although this research did not address the economic aspects of adoption of these practices. We feel confident that no-tillage and increased cropping intensity are biologically and physically feasible in the intermediate precipitation zone of the NE Oregon.