GROUND TEMPERATURE --Cultivated vs Uncultivated ground

 I'm redoing a study I did back in 2015-2016 on temperature differences in different ground conditions.  Those earlier findings can be seen by clicking on "tests" in the labels section and scrolling to the bottom to "HOBO Temperature Sensors" posting.

This current study is starting on 12/24/21 in near freezing, snowing conditions. Temperature readings will be taken every 2hrs until we start seeding the spring crop in spring of 2022, around April.  There will be an update to this posting after seeding.  I started this study by spading and working up two areas to replicate a cultivated field with little surface residue.  I'm comparing this with field conditions where there is surface residue left undisturbed.  All the sites are within throwing distances of one another, one in long term CRP ground and the other in ultra low disturbed no-till crop ground.  We have had some variable weather ranging from freezing to thawing, and mixtures of rain and snow for the past week.  The field aspects are similar from one site to the other.  One difference showed immediately.  The worked CRP field had no sign of frost(pic upper left showing a lot of living roots), where the cropped field showed frozen soil about an inch deep (pic lower left showing some non-living roots).

These observed conditions support the idea that there is more biological activity in the CRP field where the grass roots are living, hence a warmer microclimate in the root zone, compared the the cropped field where there has not been living roots to stimulate biological activity for five months.  Biological activity creates heat.

    HOBO temperature/light sensors (model UA-002-08) will be placed on the surface and at the 2" depth in the cropland sites.  This is my primary interest, to see if there is a temperature difference between cultivated and uncultivated ground, both surface and subsurface locations.  The inclusion of CRP ground is to see how ground temperatures differ between cropped ground with it's limited time supporting living roots, and ground that continuously supports living roots. 

     Once put in place, these sensors will stay until recovery in early spring.  They don't support remote monitoring or downloading. 

The pic to the left shows a typical plot from the data collected with the HOBO (UA-002-08) sensor for temperature and light. A (HOBO) sensor and the "reader" is shown above the wireless keyboard and trackpad.

Soil Field Condition vs Lab Tests

These pics are examples of WW crops from two different tillage systems.  Both of these crops look pretty good as of April 13th, 2021.

<-----  Pic on the left is an example of 2021 WW on long term conventional ground.  This  crop was seeded on chemical fallow grnd.

<---- Pic on the left is an example of 2021 WW on ULD grnd.  This area was seeded too shallow and got a late start.

        This winter/spring I had a unique opportunity to run a lab test on two soils that have very different history.  One soil has ~30 years of no-till, with the last eight years being ultra-low disturbance no-till.  The other field, a couple hundreds yards away has a history of one hundred plus years of conventional tillage/cropping, with no no-till history.  Both locations were fairly level with low erosion from weather, although a difference in tillage erosion would be apparent.  The no-till field has a large amount (mat) of residue, and the tilled field has a small amount (a lot of open ground) of residue.   I had high expectations of seeing a dramatic difference in OM, EC, BD, Respiration, and some differences of several macro and micro nutrients.  WHAT A DISAPPOINTMENT!!  Some numbers were the same, and some showed slight differences, but all in all, no revelations.  This lab is not the general run of the mill type that we are all accustomed to.  I have used this lab for a couple of years for different projects. 

    Physically there is a world of difference between these two fields.  April 13th with no measurable rain since March 23rd the ULD grnd was soft to walk across, where the tilled field was hard under foot.  Sinking a 1"diameter soil probe into the ULD field was easy, down the full 4 ft length of the probe, where the conventionally tilled field was very difficult down to ~18", where resistance eased up (maybe even softer than the ULD field in the lower 2'.

        Why didn't the lab show differences as expected?    Two things come to mind.  1)- In my mind this was such a no brainer that I was careless taking the samples.  My process of taking an undefined slice of soil using a narrow trenching shovel was bad technique.  A lot of possible error could result.   2)- This supports my comments on earlier posts about lab testing, and difficulty in trying to show value of no-tilling through our long recognized lab protocols. 

     I'm convinced that no-till deals primarily with the physical component of soil health, but secondary to other processes like biological diversity and nutrient recycling.  Biological activity has to be helped with cover crops and possibly reintroducing microbiological species through well prepared compost and compost teas.   No-till is significant in improving soil drainage, and it reduces destruction of soil organisms community life.    No-till is the first step required for us (in the Palouse) in developing a healthy soil.  With few exceptions, our environment will not support tillage and develop a healthy soil.   Comparing infiltration rate, wet aggregate stability (SLAKE test), visual soil structure, and earthworm count is easy to do and shows dramatically what no-till brings to the table relating to soil health.  Bulk density should be an easy comparison, but the penetrometer is effected by moisture content, soil type and other factors that vary from point to point.   So, what do I conclude?  As many of my earlier posts mention, a no-tillage farming system, is very effective in building soil structure over time.  A no-tillage farming system, when coupled with high surface residue (soil armor) is very effective in controlling erosion from tillage, water, and wind.  A no-tillage farming system is helpful in slowing evaporation when coupled with a protective mat (soil armor) on the ground, and even more effective if also coupled with standing stubble.  Moisture is lost principally through evaporation, not crop production.  Keeping soil surface temperature down, and a low wind velocity along the soil surface, saves moisture that can be used by the crop.  Another benefit to a no-tillage system and heavy mat of residue is reduced competition from weed species, either broadleaf or grasses.  We see it consistently year after year when comparing our neighboring fields with either conventional tillage or high disturbance no-till.  Unfortunately, we still have to apply herbicides like everyone else.

Value of low disturbance Direct Seeding

I had the opportunity to compare a field with long term low disturbance direct seeding history with a bordering field having a 100+ year history using a conventional tillage system. 

The pic on the left represents the field with the 100+ history of tillage.  The pic below (middle) represents the field with a long history of low disturbance direct-seeding.  In 2020 both fields were in chemical fallow.  The field in the top pic was chem fallow on spring wheat stubble. and seeded with a high disturbance drill.  The field in the middle pic was chem fallow on spring canola stubble.  It was seeded with a low disturbance drill.

  Observation:  Both fields were thawed.   This condition followed 10 days of hard freeze that provided ice sufficient to skate on our pond.  A quick thaw followed.  The field (top pic) was squishy, wet underfoot.  The near-surface was well above field capacity for moisture.  My loafers were mucked some when walking over the field.   The field (middle pic) was firm, indicating water moved down into the profile leaving the near-surface soil near field capacity for moisture.  Along with the surface armor, there was no danger of mucking up my loafers anywhere in the field.  I could have driven my F150 over this field.    

     The pic to the left (bottom) shows a part of the same fied that has a long history of conventional tillage.  Shown is winter wheat stubble that is cut very short.  This field is likely to be chem fallowed in 2021 and seeded to winter wheat in the fall of 2021.  This stubble area is soft and mucky on the top 2" and frozen below 2", making it difficult to walk.  The recent 0.29" of moisture (snow/rain) that helped thaw the surface is held in that top 2".  I was able to compare this condition with a field on it's border with tall standing stubble that has a long history of low disturbance direct-seeding.  That field was thawed and firm underfoot indicating that the 0.29" of moisture (snow/rain) had moved deep into the soil profile leaving the surface firm and near field capacity for moisture.

     These field areas are close together and likely received the same weather, so what is making the difference in field conditions?   Two possibilities come to mind.

    1) there is no question that the soil structure is improved providing more porosity (lower bulk density) in the long term direct-seeded field compared to the long term conventionally tilled field.  The slake test would easily prove that; however, in winter, with freezing or frozen conditions, soil structure with more porosity isn't the full answer.  

    2) There has to be a temperature factor involved.  How does this factor in?  Well, --there is 34 years where our direct-seeded fields have reduced or eliminated erosion compared to conventionally tilled fields.   That's nearly a 1/3 of the time since native grass was removed from the landscape.  That time has to have an impact on soil organic matter loss (SOM).  Add to that, the time that SOM may have been building since 2010 with the introduction of our ultra-low disturbance no-till system, which includes the stripper-header, expanding our rotation to add more crop diversity, and beginning the introduction of cover crops.   My bet is that we have been able to improve our "soils health" to the point that we are getting more biological activity.  More biological activity results in more heat which in turn warms the ground resulting in faster frost melt, and along with increased porosity, allows moisture to enter deep into the soil profile drying down the surface soil to field capacity.

    I have yet to followup by doing some simple tests, and I have missed the timing for the temperature component of my theory.  My HOBO's should have been in the ground last fall and left until now.  There are several simple physical in-field tests that can be done now that indicates a comparison of bulk density and soil porosity.  I hope to get them done this spring/summer.

    

    
   

THE LONG & SHORT OF THE STRIPPER HEADER

IT'S ALL ABOUT MOISTURE  ---->  FARM TO SAVE IT OR LOSE IT
       Fact: --there is a layer at the soil surface, even though it looks dry, that is at 100% humidity.  This layer may be only 1-2micro's thick.  This layer is maintained until the soil profile can no longer draw on it's reserves.   How you manage this soil surface environment has a big impact on evaporation and the moisture available for the crop.
       Fact: --residue modifies soil temperature.  Soils are warmer through the winter and cooler during the summer with surface residue either standing or flat.
      83% of rainfall over a two year wheat/fallow rotation is lost off the soil surface through evaporation.  (see post of 9/19/2012)-- conclusion was to keep soils as cool as possible and air velocity across the soil surface as low as possible.  This translates to, --maintain as much cover as possible over the soil, and keep the cover as tall as possible, for as long as possible, to maximize moisture available for crop production.
      Our observations over 4 years indicates considerably fewer weed cultivars germinate and compete with the crop on ground that is not disturbed.  The more residue, the less disturbance, including disturbance from tracks/wheels, the better.
   
THE LONG:

       1-- Removing the straw row of a poor residue managing combine, is a major plus.  It gives new life to older machines and increases capacity by 10-20%.
      ---There is much less material being processed.  This has resulted in significant savings for us in combine repairs.

       2--Potential increase in moisture available to the crop by:  
      ---increasing snow catch (when we get it) over the standard cut or mowed height.  This resists snow drifting, leaving more even snow (water) distribution over the field.
      ---Accompanied with solar energy which warms the stems, the snow melts and enters the soil at the base of the plants in a slow controlled manner.
       ---reduced weed competition when used as part of the ULD system.  Fewer weeds, leaves more moisture for the crop.  Less surface disturbance including wheel tracks, the fewer the weeds.
       ---reducing air velocity over soil surface. Studies are showing reduced evaporation from tall stubble.  This means more moisture for the crop.
        ---reducing soil temperatures in the warm season.  Several studies, including our  own measurements with HOBO sensors show significant drop in summer surface temperatures compared to bare soil.  Studies concur, that lower soil temperatures conserves moisture for the crop.
       3--Modifies winter soil temperatures.  Our HOBO sensors are showing that tall stubble insulates the soil, not only in the summer to reduced soil temperatures, but also insulates the soil from the cold winter temperatures.
       4--The Shelbourne is a low maintenance header for us.
       5--The Shelbourne, being a sealed unit, reduces harvest dust around the combine cab.

THE SHORT:
       1--Is not useable for all the crops we grow.
              ---spring standup peas:  grade reduction from cracked/skinned seed coats.
              --mustard/canola:  problematic if stems carry seed pods extending more than 24 inches along the plants vertical axis.
              ---crops with seeds forming around a central stem like sorghum.
       2--Not all drills will successfully seed behind the stripper header.  Type and density of residue needs to be considered.
               

CONVENTIONAL TILLAGE & MOISTURE

It's that time of year!!  We, along with our neighbors have started making fallow that will be seeded to WW this fall.  There are as many ways to do this as there are farmers in the area.

I walked into this field the other day (not ours) and smelled the pungent aroma of fresh tilled soil, and also I felt a significant difference in humidity while traversing from the cultivated area into the non cultivated area.  It was a bit startling.   There is a lesson here!  (actually 5 that comes to mind.)
1--Soil moisture:  Moisture has been exposed by the cultivator and is being evaporated out of the soil at a rapid rate, raising the humidity.  Some documents I have cruised indicate approximately 0.5" lost per trip.  (Many years ago, I checked this on our operation and found that we had lost ≈0.5"+ in three operations of cultivating, weeding, harrowing to set up the fallow.)
        On this field(pic), the lack of residue (standing or not) allows air movement along the surface, removing the high humidity(100%) interface between soil an the atmosphere, --if you see dirt there isn't enough residue to protect the soil.  This high humidity layer is constantly being replaced until the soil can no longer provide the moisture.  Research shows that most of our soil moisture is lost through EVAPORATION (83%+) from the soil surface.  The best moisture saving practices keep the surface COOL and CALM.  This loss can not be eliminated, but it can be dramatically slowed.
2--Soil Temperature:  Destroying residue that covers the soil raises soil temperature.  This in turn increases the evaporation from the soil.  Research shows a 20 degrees difference between covered and uncovered soil.  Our own testing verifies this.

 3--OM is being destroyed.  Tillage introduces oxygen (air).  By combining  OM(fuel), oxygen, and heat(from ground and atmosphere), so the biological furnace is stoked and the OM is destroyed, converting to elements that include nitrogen(N), and CO2.
 4--CO2:   --is released into the atmosphere.  When soils are not disturbed, a relative balance of gases is established in the soil profile.  The two most notable are oxygen and CO2.  Cultivation, while adding oxygen to the soil releases CO2 from the soil.  There is some exchange of these gases all the time through soil interaction with plant growth and biological activity; however, soil disturbance accelerates this phenomena.  The more intense the disturbance, the greater the gas exchange.  Conventional fallow, requiring several tillage operations, releases CO2 to the atmosphere several times during that fallow period.  Minimizing mechanical soil disturbance, and building soil structure through plant diversity is the best way to provide oxygen to the soil, and control the release of CO2 into the atmosphere.
5--N:  There is no question that N is produced by this accelerated biological furnace, and standard soil tests acknowledge this by calculating an expected amount of N, from a given level of OM.
      The stability of this N seems to be the question, and I am totally confused at this point.  Nitrate N is water soluble and goes where the water goes.  Ammonia N ties to the soil particles and goes where the soil goes.  Both of these forms evolve over time.  This has been known for many decades.  A high percentage of these forms end up in the public waters.  From what I'm reading, our crops are only using about 45% of the N that we apply.  That's pathetic, costly to our operations and the environment.
       Now "Organic N" is becoming a subject of discussion.   What is this, and what distinguishes it?  From what I am reading, Organic N is suppose to be stable and available to plants.  It's not suppose to disappear except through plants or the physical removal of the organic matter from the field, --but information is all over the board on this subject and my understanding is minimal.  Please enlighten!

Our Farms Historic Rainfall

I have recently put 18 years of rainfall data in a spreadsheet ( 1998 - 2015).
---14.67"  is what it turns out to be our average yearly rainfall over the years, --with 9 years at or above, and 10 years at or below. (one point was counted in both, above/below).  The graph indicates our Ewan/St.John farm is in the 13-16" rainfall zone, instead of the 15-17" as most maps have us.  (Is this a real change from 1940-1970's)???
---Our lowest rainfall total was in 2002 with 10.31 inches.
---Our highest rainfall total was in 2006 with 18.35 inches
---Two years, 2015 & 2003, June received a trace, or no rain.  June is a benchmark for us.  Good rains normally translate to good yields, little rain translates to not so good yields.
---Six years, July received no rain.
---Five years, August had a trace, or no rain.
---June with more than 1.5 inches were (2014, 2013, 2012, 2010, 2005 ).  These were great crop years, or, had the potential had not other climatic forces become involved, --for example, Nov. of 2013 had an event where high winds accompanied by a sudden drop in temperature severely damaged the 2014 winter wheat through out the Palouse.  Most people had patches of good wheat, but the general yield was down approximately 25-30%,
---Our ULD system that incorporates the Shelbourne header and the CrossSlot drill is an attempt to lessen dependency on good June rains by reducing moisture loss through runoff and evaporation.  2014 was a great year to test the theory, but alas, the June 12 freeze ruined the potential of all our crops, both winter and spring.  All surviving crops were delayed in maturity, and the unusually high heat of July & August caused further damage.  The CrossSlot did all it was advertised to do, and the crops got a great start, but circumstances beyond our, or it's control lowered yields.
---Our rainfall tends to cycle up for three years, then, down for three years.  (+/- ?)
---If that pattern holds we may rise through the average precipitation line in 2016, and give us, depending on the June rains, a good crop, both winter and spring.
---The charts below use the same data, but the lines attempt to show three different aspects:  June rain,  total rain received, average monthly rain received.

Conclusions (?):  When I started this post three days ago, the goal was to state a few obvious points that stuck out in the 18 years of data, but as I got more into it, the more intriguing it became.  I'm not going into any more detail than what's been stated above; other than to say that,  I'm extremely glad we chose to upgrade to a ULD system.  In the short time (4 years), I can visually see it is paying off.  We are, and always have been in climate change.  What that means for the future is argued daily.  I'm convinced the Shelbourne and CrossSlot is the best option for meeting the challenges in the future.

StripperHeader - snow catch 2

Today I relaunched my HOBO's temperature sensors, which should have been in the ground 6wks ago.  This is in the SJ-Ewan area.  We actually had enough snow to show significant difference between mowed stubble and tall stubble.  This field was fallowed in 2015 behind WW.  The stubble stood (26-30") but has succumbed somewhat to the elements.  The mowed portion of the field stands ≈4".  The only place I encountered frost was in the bare ground site for the HOBO sensor, and it was soft.

This pic shows the mowed portion with a lot of wheel tracks, which reduced the height even more.

This pic shows the un-mowed portion.  The stubble at this point in time is a jumble.  Between weather events and wheel tracks, a lot of snow catch has been compromised.  There are snow depth variations within the standing stubble.  The snow depth is fairly even in the mowed area.

These two pics show the snow depth in the stubble on the left, and also the depth in the mowed area on the right.  The stubble here doesn't demonstrate the melt around the stems as it did in Thornton.

     Now that our interest is to keep the stubble as tall as possible, and noticing that it lays down, crumbles, or in other ways shrinks, we need to rethink some aspects of our operation to improve this condition.  Maybe: --change to narrower wheels/tires on the sprayer and combine to reduce trample.  Change wheat and barley to stiffer cultivars that will resist deterioration.  This would help maintain residue during periods when low residue crops are raised.

Soil Temperatures with Direct Seed

     General consensus by farmers in our area is that tillage warms up the ground early in the spring.  In the late 90's early spring soil temperatures were taken across the Palouse, and the result was reported to be only 1-2 degrees.
     The October 2015 edition of  NO-TILL FARMER (p.2) had a short article on temperature comparisons.   A summary of this particular article stated that shortly after planting the soil temperatures moved quickly to the same level whether tilled or untilled.  Twelve hours after seeding there was a 5 degree difference.  Twenty four hours after seeding there was no difference.
     There was no mention whether the no-till was low or high disturbance.
     This is potentially good news and we will try and verify using our ultra low disturbance system this coming spring.  We have conventional tillage all around us for a good comparison.  We do know that surface cover and standing stubble moderates soil temperatures, --both winter cold and summer heat.
   

2015 SHELBOURNE STRIPPER HEADER - DRILL DEMONSTRATION

 [Update: 7/2/15]  Since the demonstration the weather has been hot and dry.  Part of my interest in the demonstration was to see what happened to seed zone moisture.  The "configuration" stated below has a broad meaning including opener type, closing disc's, packer wheels and their relationship to the opener.  The plot started with excellent moisture and good ground cover.  a)--Narrow hoe,--the configuration left an open seed trench that wicked off the moisture.   b)--Wide hoe,--the configuration powdered the surface soil.  The ground dried to the bottom plate of the Anderson opener.  A deeper depth would probably provide the dust mulch to hold moisture for seed germination.   c)--Double Disc,--the configuration provided a lot of tillage.  There was significant loose surface mulch that dried down to the firm soil.  A deeper depth will probably hold moisture for seed germination.   d)--Angled Single Disc,--the configuration did not firm up the slot, and moisture was lost where soil had been lifted by the disc.  A packer that firmed the loosened soil would probably hold moisture for germination.   e)--Single Disc with inverted T,--the configuration held moisture the best.  As advertised, if the integrity of the slot is not compromised (left open), very little moisture escapes.  Unfortunately that's easier said then done.
    All of these designs are good direct seed drills.  The effort applied for successful seeding will vary with the unit.  The old rule of thumb still applies, --disc drills work better in standing stubble compared to flattened stubble, and hoe drills prefer stubble length to be less than the row spacing.  
    June 23, was a warm day.  Seventy five people braved the heat and dirt to see five drill styles tackle the field of mowed and standing stubble.  The event was put on by the Palouse Rocklake Conservation District.  There was a good mix of farmers from a 60 mile radius, University  and USDA people, and two dealer representatives present.  Floor Dry was used in place of seed and that turned out to be a good substitute.  The white color contrasted well with the brown dirt, and we won't be fighting volunteer cultivars all summer and early fall.
     A WSU researcher reported on their studies with the Stripper Header at the Lind, WA station.  In general, the tall stubble keeps the ground warmer in the winter and cooler in the summer.  Air velocity across the ground surface is significantly reduced with the longer stubble, which helped keep the boundary layer of high humidity at the soil surface.  In short, these factors reduce the rate of evaporation off the soil surface. As reported in an earlier post, evaporation is approximately 83% of our moisture use/loss.  Two weeks ago we placed four HOBO temperature sensors in the ground, --a) under a board firmed to the ground, b) under heavy mowed residue, c) under residue in tall stubble, and d) in bare ground with all surface residue removed, but untilled.  We will read them this fall and again next spring.  We have verified these results last year with our HOBO's.  This is an excellent site to add data for further verification.
     Grower experience with the stripper header indicate that increased capacity of older combines can be expected.  The stripper header is excellent in small grains.  We have harvested mustard with success.  We will attempt peas and garbs this year.  Theoretically the stripper header will harvest any crop that will fit under it's hood.
     Field background:  The field has been Direct Seeded  for 23 years with no residue manipulation other than mowing.  No harrowing.  The plot has 2014 winter wheat residue that had large areas mowed. Most of the area has good ground cover plus the 2014 crop residue.  The residue is very dry, and the ground under it has good moisture. The seeding area is complex with variable soils and variable residue conditions.   In the pic below, from left to right is the CrossSlot(single disc w inverted T), JD750(single disc w 7 degree angle), Horsch/Anderson(≈ 5"wide hoe), AgPro(≈1"narrow hoe), Palouse Zero Till(double disc).  All the units were designed as single pass drills, applying both seed and fertilizer.  Each drill made two passes with no changes from the original drill setup.

Results:  All the drill types were able to seed through the standing and mowed residue for the short distance encountered in the demonstration.  Some clumping and shedding of residue was noticed behind the hoe drills.  Each hoe drill did have a straw bridge at some point in the demo.  With the conditions as dry as they were, the disc drills ran easily through both the standing and mowed residue.  Straw tucking was evident, but probably not an issue with any of the disc drills.  The CrossSlot, with it's inverted T slot rarely show any effect of straw tucking even though that is the signature look.  The seed is tucked to the side in the T slot away from the straw.  The appearance of straw tuck helps eliminate sealing of the surface, making it easier for the coleoptile to emerge from the soil, while at the same time, sealing in the high humidity environment around the seed.  This design, if the slot closure is not compromised, allows seed to geminate in a lower moisture environment than other seeding systems.

     Pic above shows producers looking at the placement of the Floor Dry, and the approach of the Palouse Zero Till drill on it's return pass.

     One point of interest to me was the comparison of the CrossSlot with the JD750.  I have always accepted the idea that the JD750 was the lowest disturbance drill where it cuts-lifts-drops the soil in place.  However, the CrossSlot definitely left the field looking as if it caused less surface disturbance, and left the residue tighter on the surface.  Did the JD750 disturb more soil, and sift more seed through the residue onto the soil surface?  That is questionable.  Maybe time will tell.  Green growth and soil disturbance go hand in hand.  The more the disturbance, the more the green growth.

     A surprise to me was, which drill did more processing of the residue, and the soil surface.  I assumed that the Horsch, with it's wide hoe and recovery disc's to backfill the seed trench, would be the clear winner; however, the Palouse Zero Till with it's close row spacing may actually be more aggressive.  I think the green-up will decide the winner.

     All in all, I was pleased with the demonstration.  Hopefully the drill participants, along with the attendees learned a little, should they develop an interest in a stripper header.  It needs to be kept in mind that this was a relatively light crop with shorter than normal stubble height.  I hear that Shelbourne has recently doubled their manufacturing capacity, so, interest is apparently building.

     

HOBO Temperature Sensors

[Update 4/8/16] --Removed sensors so Kye could drill the field yesterday and replaced them today at 1:30pm.  I'm down to 5 sensors in two locations.  The heavy mowed residue site has three (#6@ 3", #9@1", #4 in the air near surface).  The bare earth site has #7@1",  #8 in the air near surface. [#8 was in tall stubble but drilling dragged all material away.
[Update 2/24/16] --Launched two sensors for air temperature just above the soil surface, --#8 in the tall stubble, --#4 in mowed area.  Should have thought of this earlier, but the thought never surfaced until a farmer suggested that tall stubble may have trapped cold temperature to the point of reducing the survival of his winter canola.  I have my doubts but there is no reason not to check it out.  Another sensor (#11) was carried off by some animal.  I found it about 30' from its flagged location (that was luck).  I have no idea of how long it was on  the surface but I have put it back in the ground in the tall stubble, --which is mostly been flattened from winter weather of wind and a little snow.  The roots are rotting, or being eaten off and allowing the plant to tip over when the forces of wind, water, snow engulf them.  This sensor in the tall stubble has not been bothered in the past as those out in the open have.  Now that it is exposed it is experiencing similar attention from critters.  I'm going to have to stake and tie these sensors more securely in the future.
[Update 1/8/16] -- Relaunched sensors from being pulled out in November.  The sensors were set for readings every 2hrs instead of 1hr.  --#1 is located under #7(bare grnd) for temperature reading ≈3" deep.  # 8 was not relaunched (couldn't locate plank).  #6 is under #9 (under heavy mowed residue).  #3 under #10 (standing residue w light surface residue).  Replaced snow cover.  Soft frost found at (bare grnd) site.
[Update 7/27/15] -- #11 HOBO has disappeared.  It is being replaced today with #E7.  It appears that the crows/ravens are drawn by the bright fluttering flags used to mark the location of the HOBO's.  They haven't bothered the flag in the tall stubble, but all flags in the mowed areas are decimated, and I can only assume they packed off the small HOBO sensor.
[Update 6/14/15] -- placed four HOBO's (#8-9-10-11) (8am, 6/14/15), in Ee field.  #8 is placed under white board on grnd that had been bared.  #9 is placed in very heavy residue that was mowed.  #10 is placed in standing residue with little surface cover.  #11 is placed in bare grnd that had been scraped clean of residue.  All the sensors are placed near each other, and vertical at the surface.
     Intention is to pull them for readings on the 22nd prior to the drill demo,  then again this fall when the field is seeded.  We'll take moisture samples at that time as well.
[Update 6/4/15] -- pulled #1 through 7 to download.  No data was recovered.  A wasted 6m.
[Update 10/30/14] -- pulled and downloaded sensors ≈ Oct. 23 and replaced them on Oct 30th.  Units #6&7 were switched when placed back in the soil.
This past year I have been playing with temperature sensors with the intent of quantifying the impact that the stripper header, and residue on the soil surface has on seed zone temperatures.  Last year I played around with them to get an idea of what they were capable of.  These units can be left in the field to collect data for a lengthy period of time.  You can down-load the data on a computer and graph in many different ways.   This summer I'm starting over with all the HOBO's positioned vertically with the top of the unit at the soil surface.  Seven total.  At the time of placement I took the soil temperature of each location as a start point.  I will update this post when something of interest pops up or at season end.

    ------[field Es]-- Two units are in a chemical fallow field with heavy residue that is totally flat to the ground. One of these units is placed in an area of heavy residue(#7) where no dirt can be seen.  At 2" my soil thermometer indicated 82 degrees.  The other one was place where dirt could be seen at the surface(#6).  The temperature at that spot was 90 degrees. This field location has a slight slope to the north.

     ------[field Ee]--Three units were placed in a chemical fallow field that was stripper headed.  There is heavy residue with stubble standing approximately 36" tall.  One unit was placed in a combine wheel track where there was some dirt showing and the residue was pressed flat to the ground (#3).  The combine had duels mounted close together, so the track is wide.  The temperature at that site was 96 degrees.  A second unit was located in an area with tall standing stubble and no residue covering the ground surface (#1).  The temperature at that site was 80 degrees.  The third unit was placed in a location that had tall standing stubble and also had the ground surface covered with residue (#4).  The temperature at that site was 72 degrees.  This field location is flat

     ----- [field En]--Two units were placed in a growing spring barley field.  The barley is only around 22" tall and fairly thin.  One unit place in heavy residue (#2).  The temperature at that site was 82 degrees.  The other unit was placed whee there was no ground surface cover (#5).  The temperature at that site was 84 degrees.  This field location has a slight slope to the south.

        SUMMARY:

     --- In field Es I was surprised that there was so little difference in the temperature between the two sites.  Did the flattened residue have an impact???

     ---In field Ee I was surprised that the wheel track showed such a high temperature compared to the other two sites.  The wheel track was more compacted.  Did that influence the temperature???  The tall stubble seems to be impacting the temperature compared to the field with the flattened residue.

     ---In field En I was surprised that the temperature was so similar between the two sites.  Does a growing crop influence the surface temperature more than the surface residue???

Cold Soil and Direct Seeding

I've happened on to a project (1994-2009) called the Alberta Reduced Tillage Inititive (ARTI).  This project had many partnerships, including private, public, and education.  They studied many aspects of Direct Seeding (DS) including effects of cold soils.  The following URL access' their site.
                          http://www.reducedtillage.ca/about.aspx
     This is a big site.  One study indicates that tall standing stubble (stripper header) warmed faster than the short stubble mat left by regular platform header,  and allowed better seed/soil contact with disc type opener.
     I will update this post as I have time to read other studies.