CHEMICAL FALLOW

[Update 6/14/16] -- All of the winter canola died during the winter.  It didn't make any difference whether is was platter size or just emerging.  We planted SW on most of the acres and Billy Beans on the remainder.  Both crops received heavy damage from a June 12th, 28 degree night, --not a great year.  The spring peas was the only crop damaged to the extent that multi peril crop insurance kicked in. [Update 10/30/14] -- Finally all our WW has emerged.  It appears that we will get most of the canola out of the ground.  We had all the pieces in place for this kind of summer and fall, but we didn't execute very well.  We got about 40% of the canola emerged timely in mid-late August, and about 50-60% of the winter wheat emerged timely mid September.  We currently have 70-85% of the canola emerged, but other than the plants emerged timely in August, it's doubtful the remainder will survive the winter.  It is still emerging.  Post analysis:  The hot weather, lack of good early soil profile moisture allowed seed depth moisture to thin earlier than expected.  The "best" residue areas were OK, but "good" residue was not.   We should have seeded the canola at the end of July instead of mid August, and we should have seeded the winter wheat a week earlier (end of August instead of first part of September).  If the ADF system had been working consistently, we may have still got 80-90% of each crop emerged timely.  Weed pressure is low in both crops.  
        We may have an opportunity to see what the yield loss may be between timely emerged wheat and that which emerged 30+ days late.   Years ago when I was regularly seeding the second week of October, I estimated that I consistently lost 15-20 bushels per acre compared to some of the neighbors.
[Update 9/20/14]
       --- Soil that has cover is noticeably cooler, and moisture stays in the seed zone longer in the fall.  It appears to be proportionate from 0 to 100% cover as to where the moisture line is at any given point of time in the fall.  Observation this fall supports an earlier post about a 1970's unpublished research project (Soil Moisture posted 8/19/12).

          I have started observing and digging in various fallow fields to see the differences that may show.        I have been in a limited number of fields to date, but what I am finding is what I have learned to expect.  "If you see dirt you don't have enough residue".  We have had, over the last two weeks, high temperatures (high 90's and a few over 100) accompanied with a lot of wind.
         Conventional fallow is hot and dried as deep as it is worked.  One field was worked shallow (≈2") and moisture was thinning below the worked area.  Another field was worked to 4"and to a finer texture and when moisture was reached it was good.  Powder dry and no (0%) residue, both of these fields will likely endure severe wind and water erosion before the crop is harvested in 2015.
         The chemical fallow fields in the area are either mowed short or have thin short stubble following harvest.  In both scenarios, they have insufficient residue to hold moisture in the seed zone.  The fields I checked were dry to ≈1.5" and thinning moisture below.  Without added moisture, it will be difficult to get a stand of winter canola, and by fall, it will be difficult to get a stand of winter wheat.
        In contrast, our field that will be seeded to winter canola, is in great shape.  We have a thick mat of residue on the soil surface, and standing stubble (36").  The soil is cool and the wind has not been whipping across the surface.  The combination of surface residue and tall stubble leaves us, currently, with moisture within 0.5", and much of the area has moisture at the soil surface.  There are holes in the field where the moisture is deeper, but 95% of the field is great at this point in time.
        We have another fallow field.   Part of the field was mustard in 2013, but the majority is CRP that we started the takeout process in July 2013.   I am including some pics with narrative to explain what I viewed.  It's notable that  the soil surface of this field whether crop or CRP is full of worm castings.

The pic above shows a lot of residue but there are significant holes in long narrow strips where dirt shows through.   A guestimate would be 90% coverage, maybe 95%.  The 2013 crop was mustard that yielded below average.  It was seeded into very dense 2012 standing winter wheat stubble with a cross-slot drill.   The area in this pic was over 120bu/a.  Without ground disturbance the winter wheat (Brundage 96) stubble has stayed pretty good.  There is no mustard residue to be seen by the casual eye.  The mustard stalks were mowed following harvest.  The operation was mainly cosmetic.  With all our residue from 2012 the mowing appears to not have hurt the moisture bank.

This pic shows one of the narrow strips mentioned above where dirt was visible.  There is residue in these spots, but you see dirt.  You can see the moisture line, and it is 1.5" below the soil surface.  You can also see what is probably the transition zone where moisture is thinning.  With no standing stubble, and inadequate residue, this spot took the full force of wind and sun.  1.5" below surface is where I found the moisture line in all the chem. fallow fields where I looked.  In all likely hood, the moisture line will continue to drop.  We are in the third week of July.  It's a long time to our normal seeding date.  Rain will be needed to start a crop this fall.  The dry looking crumble soil is all worm castings.

This pic shows the condition of most of the field.  It's included in the first pic above.  Heavy mat of residue, but no standing stubble.  The moisture line is at the surface, and it is good moisture --not thinned.  This demonstrates that residue can hold moisture and armor against high temperatures and high winds in Uhlig class soil.  The down side is, that this level of surface cover will be challenging to maintain.  

This pic is typical of the CRP/fallow that comprises most of this field.  Good residue; however, it's inadequate to hold moisture . The top 3-5" of soil  is made up almost entirely of worm castings.  They have been working without interruption for 26 years.  The moisture line on this hilltop is at 1.0".  That is better than standard chem fallow but not as good as heavy residue shown in pic above.  If you look closely, you can see dirt among the standing residue.  The standing residue is only about 12-16" tall, and much of the surface shows dirt.  

         This is a good piece of property and we are excited to start enhancement of the microbiological community that's underfoot.  This field is our best opportunity to develop a sustainable cropping system.  25 years of CRP is the kick start.  Now we have to gain the knowledge and wisdom to work out a crop rotation, and develop a plan to incorporate cover crops where practical, and possibly inter-seed an alternate crop with our cash crop, and hopefully in the not too distant future, remove fallow from the system in this 15-17" rainfall zone.