National Jointed Goatgrass Research Program

 

New Proposal-2002

 

TITLE: Effect of no-till, deep plowing, herbicide-resistant winter wheat and length of absence of winter wheat on jointed goatgrass weed seed dynamics in the soil.

 

PERSONNEL:       Principle Investigators:        Frank Young

                                                                        Joe Yenish

                                               Cooperators:     John Burns

                                                                        Olivia Forté-Gardner

 

TIME LINE:                                Initiation:       July 1, 2003

                                                Termination:      August 30, 2006

 

HYPOTHESIS: 

1.  No-till spring cereals will reduce jointed goatgrass weed seed in the soil more rapidly than a rotation of chemical fallow and no-till herbicide-resistant winter wheat.

 

2.  One-time deep plowing compared to no-till will enhance the effectiveness of continuous spring cropping for eliminating jointed goatgrass weed seed in the soil. 

 

3.  Shallow tillage prior to planting spring crops will be more effective than no-till spring crops for reducing jointed goatgrass seed populations in the soil. 

 

SUMMARY OF PROPOSAL: Funds will be utilized to conduct research to determine the effect of spring tillage on weed seed distribution and dynamics in spring cropping systems.  Research will also be conducted to determine how soon producers can return to growing winter wheat, a more profitable crop than spring crops in the Pacific Northwest (PNW).  This project is being conducted by the request of the PNW wheat growers. 

 

OBJECTIVES: 

1.  Determine if a chemical fallow – herbicide-resistant winter wheat rotation reduces jointed goatgrass populations more rapidly than 2 years of no-till spring cereals. 

 

2.  Determine if one-time spring deep plowing followed by no-till spring cereals reduces jointed goatgrass populations more rapidly than continuous no-till cereals. 

 

3.  Determine if shallow pre-plant tillage annually after one-time spring deep plowing for spring cereals reduces jointed goatgrass populations more rapidly than continuous no-till spring cereals after one-time spring deep plowing.

 

4.  Determine if 3 years or 4 years out of winter wheat production eliminates or reduces jointed goatgrass populations more effectively. 

 

JUSTIFICATION:  Over 60% of the winter wheat production area of the Pacific Northwest utilizes the century-old crop rotation of winter wheat-summer fallow.  In the PNW, this production system is characterized by severe wind erosion and heavy infestations of jointed goatgrass.  Wind erosion is reduced greatly by reducing fallow acres, increasing standing stubble, and planting spring crops.  Adoption of spring cropping systems will reduce jointed goatgrass populations (Walenta, 2001), however, in the PNW winter wheat is planted as often as possible because it is the most profitable crop grown in the region.  Growers are therefore, inquiring what spring crop tillage system is most effective in reducing jointed goatgrass populations so that they can return to producing winter wheat the most expediently.    A review of the literature indicates that presently no research has been conducted to evaluate these options.  Two seed burial studies have been conducted (PNW and Central Great Plains), which evaluated seed longevity in the soil (Anderson, et al., 2002).  In these studies, seed was buried in packets at different increments in the soil without tillage to stimulate germination.   The weed seed study with plowing is an area of research that has been identified as a specific project of high priority by the National Jointed Goatgrass Research Program. 

 

METHODS:  A field study was initiated in the spring of 2002 at the site of the previously concluded PNW integrated weed management (IWM) study at LaCrosse, WA.  Plots with the heaviest weed population in the previous 5-year study were chosen for this present research project.  These new 20 ft x 60 ft plots were in traditional, conventional fallow-winter wheat for the previous four years.  Weed seed in soil information will be used from the conclusion of the IWM study for initial baseline data in the present project.  Weed seed population in the soil will also be sampled at the conclusion of the project. Baseline and concluding weed seed populations in each plot will be sampled from six, 315 in-2 quadrats (soil surface), and six, 16 in–2 soil cores at depths of 0-4 and 4-8 inches.  Spikelet germinability will be determined using the exhaustive germination method in the greenhouse.  Soil surface and core samples will be mixed with additional soil in flats in the greenhouse, watered as necessary, and germination (plants) counts recorded every 10 to 14 days.  Germinated plants (not spikelets) will be removed, soil stirred and watered, and the process repeated for a total of six weeks.  Every year, jointed goatgrass plants will be counted in six, 385 in-2 quadrats prior to each herbicide application or tillage operation.  In the growing crop, the number of reproductive tillers (spikes and spikelets) of jointed goatgrass will be recorded prior to crop harvest. Counts will be made in at least six 385 in-2 quadrats per plot and possibly in the entire plot area as populations diminish.  Seed will be allowed to shatter back onto the ground.  Actual germinable seed production will be determined by seed production in spring wheat areas outside the plots.  Crops will also be harvested for yield. 

 

The project will contain four treatments replicated four times with a randomized complete block design.  The treatments include: a) 1yr chem fallow, 1 yr no-till herbicide-resistant winter wheat, 1 yr chem fallow, and 1 yr herbicide-resistant winter wheat; b) 2 years continuous no-till spring cereals, 1 yr chem fallow, 1 yr no-till herbicide-resistant winter wheat; c) one-time spring deep plow with spring crop, 2 yrs no-till spring cereal, 1 yr chem fallow, 1 yr no-till herbicide-resistant wheat; and d) one-time spring deep plow with spring crop, 2 yrs conservation tillage spring cereals, 1 yr light-till chem fallow, and 1 yr no-till herbicide-resistant wheat.  The crop rotation and years are shown in Table 1.  Plowing was at a depth of 7-9 inches and light or conservation tillage was disking at a depth of 2 inches. 
 

LITERATURE CITED:

1. Anderson, R., E. Zakarison, D. Ball, G. Wicks, D. Lyon, W. Donald, S. Miller, F. Young, and T. White.  2002.  Jointed Goatgrass Ecology. EB1932. Pullman, WA: WSU Cooperative Ext. 8 p.

 

2.  Walenta, D.L.  2001.  Spring emergence establishment and reproduction potential of jointed goatgrass (Aegilops cylindrica).  MS Thesis. Wash State Univ.  69p.

 

PLANNED TECHNOLOGY TRANSFER:  Data and information will be disseminated at annual field days and grower meetings and by bulletins and subsequent peer reviewed journal articles. 


 

Table1.  Yearly crop rotation    (cropping yeara) and tillage for jointed goatgrass seed dynamics study.  

 

                        Previous                                                                      

Treatmentb        4 years            2001-02           2002-03           2003-04           2004-05           2005-06

 

   1.                 WW-TFal          Chem Fal         NTCFWW      ChemFal          NTCFWW      ChemFal

 

   2.                WW-TFal          NTSW             NTSW             Chem Fal         NTCFWW      NTSW          

 

   3.                WW-TFal          Sp.Plow           NTSW             NTSW             ChemFal          NTCFWW

                                                +ConvenSW

 

   4.                WW-TFal          Sp. Plow          ConSW            ConSW            Lt.Till-              NTCFWW

                                                +ConvenSW                                                    ChemFal

                                                                                                                                                                       

a = Cropping year: September 1 to August 31.

b = WW-TFal = winter wheat + traditional tillage fallow; ChemFal = Chemical fallow; NTSW = No-till spring wheat; NTCFWW = No-till Clearfield winter wheat; Sp.Plow  + ConvenSW = Spring plow + conventional spring wheat; ConSW = Conservation tillage (disk) spring wheat; Lt.Till-ChemFal = Light tillage (one time disking in spring) then chem.-fallow

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