VALUE OF TALL STUBBLE (RESIDUE)

 [SUMMARY] --The taller and more dense the standing residue, the less snow displacement takes place.
      As, when I started direct seeding (DS) many years ago, much of the time there is nothing dramatic to see from an enhanced conservation practice, --DS compared to conventional tillage.
      But, there are exceptions, and this winter is one of them.   This winter is a showcase for what tall residue left by the stripper header can mean for the coming crop.

Above:  This pic shows snow accumulation of 12", fairly evenly distributed over the field of spring wheat stubble that stands ≈24" tall.  Compare this pic to the pic below.

     This pic shows accumulation of 6" in a neighboring field of mowed/harvested stubble standing 7".  Both fields experienced the same snow and wind events.  Notice the small area of standing stubble ≈16"tall and the snow that accumulated in and down wind of the clump.  Which condition provides more moisture for the coming years crop?  --Obviously the condition shown in the top pic.  In this instance with the snow bearing 0.25" moisture for every 2" of snow,  the field in the top pic has accumulated potentially 0.75" more moisture than the field in the lower pic.

       To continue this story, the pic above shows a conventionally tilled field seeded to ww.  The point here is that with no vertical blockage (tall residue), the recent 3" snow fall left the field and piled up in the usual places.  The very white areas are what is left of that 3" snow fall.  The slightly darker area is the old crusted snow  The field shown in the pic at the top of this post did hold most of that snow fall for an additional ≈0.25" of moisture.

 
The two pictures, above, show two fields seeded to winter wheat.  On the left is seeded into a 9 cultivar CC.  The vertical blockage is relatively sparse, but still having an effect.  The snow cover is not as even as in the more dense stripper headed wheat and barley stubble, but snow displacement is significantly less than WW fields with no vertical blockage.  We have radish in this field.  The radishes have deteriorated, leaving holes through the frost layer. We expect to retain all the moisture available from the snow for that crop.   On the right is WW seeded on spring pea ground.  The crop was seeded into heavy residue (SP plus past WW residue); however, that residue provides no vertical blockage.  There are noticeable snow drifts, indicating that we have large areas in this field where the crop is missing more than 2" of potential moisture.   In this field we will be dependent on thawing conditions.  If the thaw is gradual, we'll retain the moisture in the field although it's distribution will be uneven.  If the thaw is accelerated, we'll lose a lot of this moisture, similar to 2014.  

    (UPDATE:  In late February we had a Chinook,  which is when warm air suddenly moves in, and in this case a light rain accompanied it, that quickly removed the snow.  When I saw water in the ditch near our home, I geared up and walked the fields to see where the water was originating, --hoping it was all from my neighbors portion of the drainage.  It wasn't!!  First evident was my neighbors winter wheat on black fallow ground.  It showed like a mottled black/white area beyond the border of our field.   The snow, a thin layer because of previous winds, was mostly gone, and water was coursing down the hillside leaving a badly eroded hillside.  The ditch water was heavy laden with soil.  Little, if any, of that moisture was able to enter the ground.  Our winter wheat on chem fallow ground had good surface protection, but mostly flat from a year of fallow.  It caught very little additional snow compared to my neighbors.  I saw water was rolling down our hillsides the same as our neighbors.  The difference was that the water we were losing was mostly clear.   There was very little soil included in the ditch water.  The bright spot though was the field of winter wheat we seeded into the cover crop.  When I walked out of our ww on chem fallow into the field of ww on cover crop it was like night and day.  We had a lot of snow caught in the cover crop residue.  There was no movement of water down the slopes of that field.  Every drop of water entered the soil profile.  The cover crop (specifically the radish) did its job of saving the moisture.  The ground was frozen 4-6" deep, but the radish grew, died, deteriorated, and left a hole through the frozen soil surface that allowed moisture to enter the soil profile.)

Another observation:  I decided to check on the frost depth and whether the snow cover made a difference. This was a chilly morning in single digit temperatures and no wind.  By this time we have experienced a lot of cold weather including three nights of below zero temperatures.   In this field with 12" snow cover, one stab and a push by standing on the trenching shovel drove it more than a foot into the ground. That was a surprise, and pretty good.  It felt like the shovel was going through a big rice crispy treat.  In another field I found a bare ridge with ww and tried the same technique.  I stabbed repeatedly in the same spot and never got more than 2".  The third field, a flat, had 6" snow cover.  I stabbed repeatedly and eventually would have been able to get the shovel to the depth shown in the picture, but it would have been a hole instead of a slice.
      I'm not sure what part snow cover has played in frost depth at this point in time.
      I think the field shown above is frozen fairly deep but has developed a better soil structure over the years using DS and now has a lower bulk density.  This should allow moisture to enter the soil profile faster than the other two fields that were conventionally tilled.