Residue protects the field

This post has sat as a draft for more than a month.  It has enough information that I decided to finish and publish rather than delete.  It's been a unique year.  I could visually compare--(heavy residue vs no residue, contour seeding vs vertical seeding)

     In February I scouted our winter wheat fields mostly for erosion, and comparing drilling patterns and ground cover.  It was consistent across the region, --on our fields as well as the neighbors.  This year, all of our winter wheat is planted on either, spring or winter pea stubble.  One field has full ground cover and the other has a lot of dirt showing.   There are so many potential variables(slope, aspect, micro-climates, etc), that frequently it is difficult to see a consistent pattern.  This year was different because of the type of winter.  Most of the region received about the same weather over a long period of time.  The whole region experienced abnormally high rain and snow fall this winter. Erosion followed the book where direct seeding showed significantly less erosion than cultivated fields.   Also, the more  surface cover, the less the erosion in direct seeded fields.  

This pic shows early drying of an eroded field.  The "sponge" top soil has been eroded off the ridges and well down the slope.  The dark areas are still showing surface moisture that hasn't evaporated off yet.  These areas are benefiting from water moving from the low water holding capacity areas of the field along with the fact these areas probably have more OM (sponge layer).  There is no surface protection on this field.  

This picture shows two different fields.  The typical cultivated field is at the top the picture,  and a direct seeded field at the bottom.  The aspect is north and the pic shows where deep snow drifts lingered in both fields.  The field at the top had no surface cover other than a nice stand of small wheat.  The field in the lower part of the picture had enough residue (wheat and pea) that very little dirt could be seen and was seeded with a cross-slot drill.  The lower field did not have visible soil erosion, but it did lose water.

This picture shows the amount and type of residue that is protecting the soil surface of the direct seeded field pictured above.  This is a combination of winter wheat and spring pea stubble.  This year, our heavy residue fields are showing rodent damage where the drill left piles.  It appears that those areas are recovering.  We have seen this once in the past where piles of loose straw sheltered rodents under the snow.

This picture shows a winter wheat field on winter pea ground.  This field had two years of low residue and seeded late to winter wheat.  The field history was (chem fallow seeded to winter canola that failed, then seeded to spring wheat, then dormant seeded to winter peas, and now seeded very late, do to the fall rains, to winter wheat). It looks like there is no crop, but the crop  has come through fine.  Even though we use a ULD system and have direct seeded for 20+ years,  if there is little or no cover on the ground there will be visual erosion.  Seeding vertical down the slope accentuates the issue. This field also shows the value of seeding on the contour rather than vertically.  The extreme left side of the picture shows the contrast between contoured and vertical seeding.  The contoured seeding had some soil movement, but you have to look closely to detect it.  Most of the field had some cover.  The corners with multiple tractor/drill passes (as shown above) were the most vulnerable areas.  This area has very light soils and regularly gets beat up with any field operation.

2017 Wheat College

This year's Washington Association of Wheat Growers "Wheat College" was held in the Three Rivers Convention Hall, Kennewick, WA., 4/28/17.  The Three Rivers facility is a great venue.  I found the program interesting.  Attendance was low.  I counted ≈55 total (staff, speakers, producers).  I'm guessing most producers are still in the fields trying to get crops seeded.  The weather has provided an abundance of moisture and a late start for field work.

           CHEMICAL APPLICATION:  The key note speaker was Greg Kruger from North Platte, NE, a professor/researcher.  The organizers should have extended the day by 1-1.5hrs and gave him a second session.  He didn't tell us anything that a licensed applicator shouldn't already know; however, he did emphasize drift issues, their causes, that resulted in lawsuits.  I am listing a few of the points he made about spray applications and off target drift potential.
      ----Spray crops at the right height.  A good rule of thumb is one inch above the targeted plant for every inch of spray nozzle spacing.  20" spacing means 20" above the target plant.  The information below, where appropriate, is taken 90 feet downwind and at the appropriate tip height, as the base measurement being compared.
      ----Wind speed should be checked at application height, not 12' off the ground from a self-propelled rig. ( Well, in Nebraska or other flat land areas, maybe that caution has merit; however, in our steep rolling terrain, I don't see that as a useful factor.)
      ----Drift has two facets: one, is particle, where particles are physically carried off target by wind.  The second is vapor.  Vapor is controlled by chemical structure and is out of the hands of operators to manage.
      ----Each herbicide has a preferred application droplet size.  You should choose the proper tip for the application speed, and related pressure range to maintain that droplet size.
     ----You can visually see a 25 micron change in droplet size.  Learning the proper spray pattern will  help you keep the spray pattern within the preferred droplet size.
     ----Air inversions are common in early morning and evening with still air.  The Pacific Northwest has more air inversions than any other part of the US.  Avoid spraying during periods of air inversions.  Chemistry can be carried a long way off target with inversions.
     ----Chemistry can be carried 7 times farther with wind speed that has been doubled.
     ----Chemistry can be carried 3.5 times farther when booms are raised double their appropriate height.
      ----Doubling the distance to a susceptible crop will reduce the damage to that crop by 80%.
      ----Check tip specification and replace any that are more than 10% off rate.  Worn tips will dramatically effect droplet size, and coverage.
     ----AI tips are used to increase droplet size by introducing air into the solution stream.  With AI's, you are sacrificing potential coverage, depending on target weed, for a coarser droplet.  The presenter likes the AI-XR's for an all purpose tip.  They have a droplet size of 400/450.  The standard AI's are 500/600 micron.
      ----To maximize the use of any given tip, keep your pressure at least 10psi above the low end recommendation, and 15/20psi below the high end recommendation.
     ----Dry herbicide products come with their own measuring cups.  They are accurate within 7-15% depending on the chemistry.  Always use the cup that comes with the box of chemistry.  These calibration marks change with the manufacturing source of the chemical.  For real accuracy a calibrated scale should be used.  Suitable scales can be purchase for ≈ $80.
     ----The first agricultural applied herbicide was 2-4D (dry) in 1947.
     ----The last "mode of action" for plant protection herbicides was discovered in 1986.  All the new herbicides are reformulations of old ones.  Any new "mode" would take 8-10 years before it could be on the market.  Protecting the effectiveness of our current chemistry is paramount, and managing to reduce potential plant resistance should be a priority for your farm.
     ----Chemical specific crops (roundup ready, liberty link, ect.) limits the interest and financial ability to discover new chemical control for weeds in crop cultivars.
     ----Any type of cultural practice used over a long period of time will promote resistant bio-types regardless of whether it is through the use of a chemical, cultivation, hand weeding, or is "organic".  The first resistant bio-type, for the culture of the time, can be tracked back ten thousand years.  A rotation of crops, chemistry, and practices, is the best method of reducing resistant bio-types in agriculture.

Dana Herron & Jay Atchison gave a Wheat Commission report:
      ----Heaven forbid a kernel of GMO wheat reaching an export terminal.  Trade would be disrupted for a year or more.
      ----Buckwheat:  Be careful if you use buckwheat as an alternate crop.  Manage so that there will be no buckwheat show in your wheat sample.  Japan treats buckwheat like we do peanuts.  If you do find buckwheat in your wheat fields, let it be known.  There is no trade issues other than with Japan for buckwheat.  The contaminated wheat/buckwheat lot can be directed to other buyers.

Drew Lions:
      ---Rattail fescue control.  Zigua (brand name) has shown good control of rattail fescue.  The active ingredient is Pyroxisulphome (sp).
      ---Mixing two chemicals with the same mode of action does not increase the effectiveness over using either chemical. --there is a slight chance that using two chemicals with the same mode of action, but are from different families of chemistry, may improve control of a specific weed, but that's not very likely.
     ---All chemical applications are better and more consistent when spraying with more solution, except Glyphosate.  With Glyphosate more water means more chemical will be tied up with the mineral content in the water.  Ammonium nitrate is used to buffer the water, filling the sites that would be filled  with the glyphosate molecule.  This means that is very important to put nearly all the water along with the ammonium sulfate into the tank before adding in the glyphosate.  WSU website has a calculator for the amount of ammonium sulfate to use for a specific hardness of the water being used.