BIOAg Project Progress Report November 20, TITLE: Winter Canola as a Rotation Crop in the Low and Intermediate Precipitation Zones

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1 BIOAg Project Progress Report November 20, 2009 TITLE: Winter Canola as a Rotation Crop in the Low and Intermediate Precipitation Zones Principal Investigator: William Schillinger, WSU Dept. of Crop and Soil Sciences Farmer Cooperators: Ron Jirava, Ritzville; Hal Johnson, Davenport; Bruce Sauer, Lind Cooperating Scientists: Ann Kennedy, USDA-ARS; Tim Paulitz, USDA-ARS Support Staff: Tim Smith, WSU; Steve Schofstoll, WSU Overview: Multiple-year experiments are being conducted in the low (Lind and Ritzville) and intermediate (Davenport) precipitation regions of eastern Washington to document the rotation benefits of winter canola (WC) in wheat-based cropping systems. Some growers have reported that wheat following winter canola has less disease and weed pressure and produces considerably higher grain yield compared to monoculture cereals in either a two-year winter wheat-summer (WW-SF) rotation or three-year WW-spring wheat (SW)-spring barley rotation. Additionally, it has been observed that water runoff from frozen agricultural soils does not occur from winter canola stubble; presumably because the deep tap root provides open channels for water to penetrate through the frozen surface soil layer. Neither the boost in winter wheat grain yield or the soil physical, biological, or pathological factors, that may account for better water infiltration and increased wheat yield as affected by having winter canola in the crop rotation, have been documented. Objectives: To determine the benefits of winter canola grown in (i) a 4-year WC-SF-WW-SF rotation compared to the traditional 2-year WW-SF rotation in the low-precipitation zone and, (ii) a 3-year WC-SW-SF rotation compared to a WW-SW-SF rotation in the intermediate precipitation zone on: 1. Grain yield of the subsequent winter wheat (low zone) or spring wheat (intermediate zone) crop. 2. Soil microbial changes after winter canola versus after winter wheat. 3. Plant diseases of the subsequent winter wheat (low zone) or spring wheat (intermediate zone) crop. 4. Soil water infiltration and frozen soil runoff after winter canola versus after winter wheat. 5. Economic assessment. RESULTS FOR 2009: 1. Lind. Seeding conditions in August 2008 were very dry at Lind because only 6.77 inches of precipitation occurred during the crop-year (Sept. 1 Aug. 31). Due to dry soil conditions, we applied three inches of irrigation water before planting both winter wheat and winter canola. Adequate stands of both crops were achieved (Fig. 1). Both the WW and WC survived bitter cold temperatures without snow cover in December In July 2009, grain yield of WW was 43 bushels per acre (2580 lbs/a) and WC was 520 lbs/acre (Fig. 2). The plots will be summer fallowed in and then planted to winter wheat in August 2010 to determine the rotation benefit.

2 Fig. 1. Winter canola at Lind, WA in April The crop survived air temperatures of -10 degrees F with no snow cover in December Fig. 2. Grain yield of winter wheat and winter canola at Davenport in 2008 and 2009 at Lind in Spring wheat grain yield at Davenport in 2009 was reduced by 13 bushels per acre (780 lbs per acre) when the previous crop was winter canola versus winter wheat. The 2009 crop year was also very dry at Lind, with just 8.00 inches of precipitation. We planted winter canola on five occasions beginning in late June but had difficulty achieving stands because of hot temperatures after planting or before emergence or birds digging out WC seedlings before they could emerge. We finally applied some irrigation water, planted WC yet again and have a partial stand (birds consumed the remainder).

3 2. Ritzville. The seed zone of summer-fallowed soils was way too dry to plant WC in August 2008 as well as August 2009, thus no trial was established at this location during these years. Please refer to previous BIOAg progress reports for details about WC rotation benefit effects at the Ritzville site. 3. Davenport. Spring wheat following WW yielded 3420 lbs/a (57 bu/a) compared to 2600 (43 bu/a) following WC (Fig. 2). These results were very similar to what we measured at Ritzville in The decline in WW yields following WC versus WW at Ritzville was closely correlated with soil water content (WC uses more soil water than WW). However, at Davenport, the difference in soil water at time of planting spring wheat was only 0.6 inches (Fig. 3). This, alone, cannot account for the 13-bushel yield difference in spring wheat following WW versus WC. Clearly, this research needs to be carried out for several more years to get the complete picture on rotation benefits with WC. Fig. 3. Total soil water content (inches) to a depth of six feet immediately following harvest of winter canola and winter wheat in August at Davenport (2008) and Lind (2009). Also shown is soil water content at time of planting spring wheat at Davenport in May Winter canola was planted in late July 2009 and stands are excellent (Fig. 4). Winter wheat was planted in mid-september 2009 and it, also, has excellent stands (Fig. 5). Seed zone water has always been excellent in chemical fallow at Davenport and achieving stands of WC at this site is not a problem.

4 Fig. 4. Excellent stand of winter canola direct seeded into chemical fallow at Davenport experiment site. Winter canola stand establishment is not a problem in the intermediate precipitation zone. Photo was taken on September 9, Fig. 5. Winter wheat and winter canola stands in the Davenport experiment. Photo was taken on September 30, 2009.

5 PUBLICATIONS (2009 only) Schillinger, W.F., D.L. Young, A.C. Kennedy, and T.C. Paulitz Diverse no-till irrigated cropping systems instead of burning and plowing continuous wheat. Field Crops Research 115: Schillinger, W.F., T.A. Smith, S.E. Schofstoll, R. Jirava, and H. Johnson Rotation benefits of winter canola on the subsequent wheat crop. In 2009 Field Day Abstracts: Highlights of Research Progress. Dept. of Crop and Soil Sciences Tech. Report 09-1, WSU, Pullman, WA.