Investigator: Aaron Esser, WSU Extension Agronomist, Lincoln-Adams Area.

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1 Project Title: Impact of Crop Rotation and Alternative Crops on Weed Populations, Yield, and Economic Performance in Direct Seed System in the Intermediate Rainfall Area of Washington. Investigator: Aaron Esser, WSU Extension Agronomist, Lincoln-Adams Area. Interim ort Objectives: The objectives of this project are to evaluate the impact of various direct seeded crop rotations that include winter wheat, chemical fallow, spring grains and broadleaf crops on yields, weed populations, soil moisture, soil quality, and overall profitability. Key Words: alternative crops, crop rotations, direct seeding, chemical fallow Statement of Problem: Growers in the intermediate rainfall area of Washington have struggled to make direct seeded continuous cropping systems work both agronomically and economically during the abnormally dry summer conditions experienced during the past few years. Because of these struggles, grower s interest in chemical based summer fallow systems and incorporating winter wheat into crop rotations has increased. Lack of information about the effect of alternative crops on cereal grain production has also limited the effectiveness of designing profitable direct seeded crop rotations in the intermediate rainfall area of Washington. Zone of interest: Intermediate rainfall zone Abstract of Research Findings: This study is being conducted at the WSU Wilke Research and Extension Farm near Davenport, WA to evaluate the impact of various direct seeded crop rotations that include winter wheat, chemical fallow, spring grains and broadleaf crops on yields, weed populations, disease, soil moisture and quality, and overall profitability. The study is a randomized complete block design with 4 replications, and remains in the early stages. Heavy infestation of common rye (Secale cereal L.) and downy brome (Bromus tectorum L.) continue to limit production and profitability of rotations that contain winter wheat direct seeded into chemical fallow and severely limit the production and profitability of rotations containing direct seeded re-crop winter wheat. Wild oat (Avena fatua L.) to a lesser degree also limited winter wheat production. Chemical fallow plots were treated with 3 applications of glyphosate and were mostly weed free throughout the year and seed zone moisture has been available at the time of seeding. Winter wheat yields remain the most variable ranging from as high as 74.5 bu/ac to as low as 15 bu/ac. Grain quality, gross economic return, production cost, and return over cost of each rotation is being collected and will be summarized in future reports. Results and Interpretation: Background and Methods: The focus of this project is to evaluate the impact of various direct seeded crop rotations that include winter wheat, chemical fallow, spring grains and broadleaf crops on yields, weed populations, soil moisture, soil quality, and overall profitability. Results from the four year Wilke project concluded that cereal production in a rotation was generally the only crop that was profitable, therefore, maximizing cereal yield (especially winter wheat) in a rotation is desirable. This experiment was initiated in the spring of 2004 and remains in the early stages. It is being conducted at the WSU Wilke Research and Extension Farm near Davenport, 46

2 WA in an area with historically 15 inches of precipitation per year. To date only 6 of the nine rotations have been through a complete. The nine crop rotations are as follows: Rotation #, Crop Sequence Years of Rotation % Rotation in WW 1 sb sw sf/ww sw/cf/ww sb/cf/ww sg/bl/ww sw/sb/bl/ww Sg/bl/cf/ww Sg/sg/cf/ww/ww 5 40 Abbreviations: sb, Baroness spring barley; (sw), Alpowa common soft white spring wheat; ww, Chukar soft white winter club wheat; cf, chemical based fallow; sg, Tara 2000 Dark Northern Spring wheat; bl, IdaGold yellow mustard. The study is a randomized complete block design with 4 replications. Prior to initiating the study, the site location had been direct seeded for five years with replications I and II being on ground in a 3-year crop rotation that concluded with yellow mustard and replications III and IV being on ground also in a 3-year crop rotation but concluded with recrop winter wheat. Plots are 48 by 12 feet in size. All crops are fertilized at time of seeding based on soil tests and projected crop yield. The study is seeded with a Fabro double disk direct seed plot drill with a leading coulter for nitrogen fertilizer placement. Starter fertilizer is applied with the seed. Soil Moisture and Precipitation: Soil moisture data is being collected prior to seeding crops both the spring and fall of the year to determine yield potentials for nitrogen fertilization as well as water use efficiency of each rotation. Data collected will be analyzed and presented in following reports. Figure 1 presents the precipitation for the crop year. Overall the 17-inches of precipitation were very close to the historic average 16-inch average. Herbicide Application and Chemical Fallow Management: Weed pressure was assessed during mid July scoring each plot 0-10 with a 10 being weed free and a 0 being a very heavy infection that were previously removed with a mower and treated with glyphosate. Overall annual and winter annual grassy weed pressure at the study location has been reduced (45% less plots removed with mower than 2005) but remains very high, especially in replications III and IV. Winter wheat in all but rotation 5 was treated with Olympus Flex at 3 oz/ac to control downy brome (Bromus tectorum L.). Winter wheat in rotation 5 was not treated for cheat grass because of herbicide plant back restrictions. All winter wheat in rotation was treated with 2,4-D at a rate of 16 oz/ac to control broadleaf weeds. Glyphosate was applied prior to seeding spring planted crops to control weeds and volunteer crops. All spring wheat and spring grains in rotations were sprayed with 10 oz/ac Discover for wild oat control and 16 oz/ac of 2,4-D for broadleaf control. Spring barley in rotation was sprayed with a tank mix of 10.6 oz/ac Puma and 12 oz/ac MCPA for wild oat and broadleaf weed control. Mustard in rotation was sprayed 8 oz/ac Assure II for wild oat control. Overall 47

3 spring-in-crop herbicide applications were delayed because of adverse weather, thus reducing effectiveness and reducing yield because of excess crop competition. Chemical fallow plots were maintained with three applications of glyphosate as needed but weed pressure was greater than previous years with and an average weed pressure score of 6.0 (data not presented). Glyphosate was applied on April 10, and June 24, 2006 at 21 oz/ac. The applications were tank mixed with a nonionic surfactant and ammonium sulfate and applied at 12-gal/ac. Glyphosate was applied at 24 oz/ac and tank mixed with 16 oz/ac 2,4-D and a nonionic surfactant and ammonium sulfate and applied at 12-gal/ac on August 21, Stand Establishment, Weed Pressure and Grain Yields: Crop establishment was collected and overall plant populations were typical for the region including good stand establishment on winter wheat seeded into chemical fallow (data not presented). Winter wheat seeded into both mustard and winter wheat residue was slower to establish but plant populations were acceptable. Cereal grain protein and test weight data is still being analyzed. Weed pressure was analyzed over all 26-crop treatments, and yield was analyzed for each crop type. Similar to the two previous years, replications III and IV, which was re-crop winter wheat prior the study in 2003, had greater weed populations and less grain yield than replications I and II (data no presented). Winter wheat was the most variable crop in both weed control and yield. Weed control scores ranging from 5.75 to as low as 2.0, and yield ranged from an average of 74.5 bu/ac in rotation 8 to only 15.4 bu/ac in rotation 9 (Table 1). A heavy infestation of common rye (Secale cereal L.) was noted. Downy brome and wild oat (Avena fatua L.) populations were also noted. No differences were detected in spring wheat within different rotations in weed pressure and grain yield. Weed pressure averaged 7.50 and grain yield averaged 31.2 bu/ac (Table 3). Despite in crop herbicide applications, broadleaf weed pressure and wild oat populations were noted throughout the spring wheat plots. Similar to spring wheat, no differences in weed pressure was detected in spring barley with an average score of 7.58 (Table 3). Also similar to spring wheat, broadleaf weed pressure was low but infestations of wild oat were noted throughout the spring barley plots. Differences in grain yield were detected as spring barley in rotation 5 following winter wheat averaged 1.28 ton/ac, and was higher yielding than spring barley in rotation 7 following spring wheat which yielded only 0.93 ton/ac. All spring grain plots were Dark Northern Spring wheat this year based mostly on market price and yield potential. Similar to spring wheat, no differences in weed pressure and grain yield were detected among the spring grain treatments as weed pressure averaged 7.63 and grain yield averaged 31.5 bu/ac (Table 4). Despite in crop herbicide applications, broadleaf weed pressure and wild oat populations were noted throughout the spring wheat plots. Unlike the previous year, yellow mustard had a trend for greater weed pressure than the cereal crops. Similar to the spring wheat and cereal treatments no differences in weed pressure and 48

4 yield were detected amount the yellow mustard treatments as weed pressure averaged 4.50 and yielded only 331 lb/ac (Table 5). Delayed wild oat herbicide application because of adverse weather reduced yield because of increased competition from severe wild oat infestations and reduced control. Broadleaf weed populations were also noted throughout the yellow mustard plots. Economic Performance: Economic performance of each rotation is being determined. Gross economic return will be determined using the F.O.B. price on September 15, 2006 at Ritzville Warehouse and an average 2006 yellow mustard contract price for the region (personal communication). Variable costs include seed, fertilizer and herbicides will be established utilizing the 2003 Enterprise Budgets for Spring Barley, Spring Wheat, and Winter Wheat Using Direct Seeding Tillage Practices, Lincoln County, Washington. Additional costs, including equipment and overhead, will not be included as they are assumed to be equal over all rotations. Impact of Research: To date the impact of this research has been very limited as results remain preliminary as not all rotations have gone a complete cropping cycle. At the conclusion of this study, producers throughout the intermediate cropping area will have a better understanding of profitable direct seeded crop rotations and incorporating winter wheat and chemical fallow into direct seed crop rotations. Interaction With Other Scientists Conducting Related Activities: This project is complimentary to other cropping systems projects currently funded by STEEP. Chemical fallow plots, in the absence of high Russian thistle (Salsola iberica Sennen) populations, are managed in relationship to Joe Yenish et.al STEEP funded project work examining herbicide efficacy in chemical fallow management. Additional interactions include Bill Schillinger, Rich Koenig, Don Wysocki, Jim Cook and Dennis Roe. Publications and Presentations: Data and project results remain very early for wide spread dissemination to area growers and has been limited to project and rotational goals and what expected outcomes are anticipated. With that, this project was shown and discussed at the 2006 Lincoln County Extension tour and were briefly discussed at the Wilke Field Day in Specific aspects of the trial will be utilized in winter grower meetings as well. 49

5 Table1. Weed pressure and grain yield within the winter wheat plots following either chemical fallow or recrop in various crop rotations at the WSU Wilke Farm near Davenport, WA in Grain Yield (bu/ac) #8 sg/bl/cf/ww #5 sb/cf/ww #3 cf/ww #9 sg/sg/cf/ww/ww #4 sw/cf/ww #7 sw/sg/bl/ww #6 sg/bl/ww #9 sg/sg/cf/ww/ww LSD (0.05) Table 2. Weed pressure and grain yield within the spring wheat plots in various crop rotations at the WSU Wilke Farm near Davenport, WA in Grain Yield (bu/ac) #7 sw/sg/bl/ww #4 sw/cf/ww #2 cont. sw LSD (0.05) n.s. n.s. 50

6 Table 3. Weed pressure and grain yield within the spring barley plots in various crop rotations at the WSU Wilke Farm near Davenport, WA in Grain Yield (ton/ac) #5 sb/cf/ww #1 cont. sb #7 sw/sb/bl/ww LSD (0.05) n.s Table 4. Weed pressure and grain yield within the spring grain plots in various crop rotations at the WSU Wilke Farm near Davenport, WA in Grain Yield (bu/ac) #9 sg/sg/cf/ww/ww #6 sg/bl/ww #9 sg/sg/cf/ww/ww #8 sg/bl/cf/ww LSD (0.05) n.s. n.s. Table 5. Weed pressure and grain yield within the broadleaf plots seeded to yellow mustard in various crop rotations at the WSU Wilke Farm near Davenport, WA in Grain Yield (lb/ac) #7 sw/sg/bl/ww #6 sg/bl/ww #8 sg/bl/cf/ww LSD (0.05) n.s. n.s. 51

7 5 (inches) Oct-05 Nov-05 Dec-05 Jan-06 Feb-06 Mar-06 Apr-06 May-06 Jun-06 Jul-06 Aug-06 Sep-06 Figure 1. Precipitation by month recorded during the crop year at the WSU Wilke Farm near Davenport, WA in Overall there was 17 inches of precipitation recorded during the crop year. 52