Soil Moisture: Managing a Limited Resource Wisely

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Soil Moisture Managing a Limited Resource
Wisely
John Holman, PhD Cropping Systems Agronomist
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How did we get here?

• Fallow not originally part of the Great Plains
  cropping system
• Fallow stabilized crop yields in wheat-fallow vs.
  continuous wheat
• 30s, 50s, and Today

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Winter Wheat
Nielsen et al.
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What is Plant Available Water?
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PSE Precipitation Storage Efficiency
SWend SWbeg
PSE
Interval Precip

• Soil water retained Precipitation stored during
  the fallow period

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How do you measure Water Use?
Water Use Soil Water Change
Precipitation Irrigation - Runoff -
Deep Percolation
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How do you measure Water Use?
Water Use Soil Water Change
Precipitation Irrigation - Runoff -
Deep Percolation
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What Factors Affect PSE?

• Residue am0unt and orientation, tillage
• Air temperature, humidity, solar radiation, wind
  speed
• Timing, amount, and form of precipitation
• Soil texture, infiltration rate, existing
  moisture condition
• Time between precipitation events

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Effect of Tillage W-F 1993-1998 (Tribune, KS)
Schlegel et al.
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Vigil et al. 2012
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PSE During Fallow in W-F
Nielsen, et al.
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Precipitation Storage Efficiency
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Crop Choice Effect on Surface Residues and
Fallow Efficiency1998-2008
Schlegel et al.
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Wheat Residue Soil water storage Grain
Sorghum Yield
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Time of Year Efficiency from Row-Crop Harvest to
Wheat Seeding (W-S-F)
Schlegel et al.
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Concluding Thoughts

• Make decisions that will improve precipitation
  use efficiency
• Good fallow management
• No-till, residue, and weed control
• System Intensification
• Can we intensity with cash or forage crops
• Flex-cropping take advantage of opportunities
• But efforts need to keep in mind do no harm
• Hits on subsequent crops reduce surface residues,
  etc.

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Where do we go from here?

• We know when fallow is inefficient
• W-F, no moisture storage during the second summer
  fallow period
• W-S-F rotation works great when we have rain!
• W-S-F, no moisture storage from July to wheat
  planting
• Can we grow a short-season spring crop in fallow?
• W-S-Flex fallow
• Plant a spring crop when conditions are favorable
• Can we strike a balance?

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Western Kansas Flex-Fallow Results Garden City,
KS Average Precipitation (1908-2012) 18.22
in Average Precipitation (2008-2012) 15.75
in Average Precipitation (2010-2012) 13.33 in

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Kansas Annual Precipitation, 1971-2000
Source K-State Weather Data Library --
www.oznet.ksu.edu/wdl
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Flex-Fallow Treatments (Cover, Forage, Grain)
Season Crop Year Produced Year Produced Year Produced Year Produced Year Produced
2007 2008 2009 2010 2011
Winter Yellow sweet clover x x
"" Yellow sweet clover/Winter triticale x
"" Hairy vetch x x x x x
"" Hairy vetch/Winter triticale x x x x
"" Winter lentil x x x
"" Winter lentil/Winter triticale x x x
"" Winter pea x x x x x
"" Winter pea/Winter triticale x x x x
"" Winter triticale x x x x x
"" Winter pea (grain) x x x
Spring Spring lentil x x x x x
"" Spring lentil/Spring triticale x x x x
"" Spring pea x x x x x
"" Spring pea/Spring triticale x x x x
"" Spring triticale x x x x
"" Spring pea (grain) x x
Other Chem-fallow x x x x x
"" Continuous winter wheat x x x x x
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Cover and Forage Crop Termination
Winter terminated May 15 (winter triticale
heads) Spring terminated June 1 (spring
triticale heads) Plots split ½ hayed ½ sprayed
out and left standing
Winter Peas
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Plant Available Water at Wheat Planting Standing
Cover Crop vs Hay

• Cover gt0.8 inches than hay (0-6 ft)

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PAW at Wheat Planting-Fallow Method (2008-12)
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2009-2012 Yield Results
2 good years, 2 very poor years Cover Crop vs Hay
Crop no effect
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Economic Results
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Economic Results Summary
Return Winter Winter Winter Winter Winter Winter Winter Winter Spring Spring Spring Spring Spring Spring None
Vetch Vetch/Trit Lentil Lentil/Trit Pea Pea/Trit Trit Wheat Lentil Lentil/Trit Pea Pea/Trit Trit Pea, grain Fallow
Cover crop -111 -122 -53 -100 -92 -126 -121 - -58 -88 -95 -103 -98 - -
Hay -124 9 -73 14 -97 7 28 - -68 -51 -55 -47 -29 - -
Grain only - - - - - - - -46 - - - - - -38 -48
Best alternative -76 56 -25 61 -50 55 75 2 -20 -3 -8 1 19 10
Fallow costs 48/A Returns include any reduction
of following wheat yield Winter and spring
triticale hay, grain peas, cont. wheat
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New Study (W-S-F)
Spring oat versus triticale? Radish or turnip
planted with wheat ? Clover planted with
sorghum? Cocktail mixes?
Crop Hay Cover Grain
Fallow
Spring pea x
Spring pea/Spring oat x x
Spring pea/Spring triticale x x
Spring oat x x
Spring triticale x
Yellow sweet clover (planted with sorghum) x x
Daikon radish (planted with wheat) x
Shogoin turnip (planted with wheat) x
Cocktail mix x x
(oat, triticale, pea, buckwheat, forage brassica forage radish) (oat, triticale, pea, buckwheat, forage brassica forage radish) (oat, triticale, pea, buckwheat, forage brassica forage radish) (oat, triticale, pea, buckwheat, forage brassica forage radish)
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PAW at Wheat Planting-Fallow Method (2012-13)
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Results

• Impact on wheat yield and profitability
• Depends on wheat yield potential
• Wet years little to no impact on yield (yield
  70 bu/A)
• Dry years
• 2011 dry year (WF yielded 23 bu/A)
• Spring crops lt 3 bu winter crops lt 6 bu
• 2012 second dry year (WF yielded 32 bu/A)
• Spring crops lt 23 bu winter crops lt 24 bu
• Average year?
• IF you knew you were going to be in a drought W-F
  best
• What is the best choice long-term?
• How much weight do you put on a record drought
  year?

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Results

• Spring triticale forage
• 4 years of no yield impact 1 year yield reduced
• 2008, 2009, 2010, 2011 no impact
• 2012 -24 bu
• On average wheat yield -2.5 to 5 bu/A (range 2
  to -24)
• 1 ton forage _at_ 110/ton
• Net 19 to 36/A more than chem-fallow long-term
• Net 54/A more than chem-fallow without 2012
• Break-even yield reduction of 7.5 bu/A _at_ 7.00/bu
• Wheat-fallow yield potential of lt25 bu requires
  fallow

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Conclusion

• It is only sustainable if it is profitable
• Graze it, bale it, or combine it!
• No difference if grown as forage or cover
• Good fallow management
• No-till, residue, and weed control
• High seed cost, offsets N contribution- grow own
  seed
• More economical to apply N
• Select fallow replacement crop adapted to region
• Terminate cover crop prior to June 1 for winter
  wheat
• Check with your insurance provider
• If moisture is available then intensify rotation,
  otherwise fallow (flex-fallow)
• Harvesting crop as forage or grain in place of
  fallow can increase profitability

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Reducing Fallow and Tillage in Dryland Cropping
Systems
Alan Schlegel Southwest Research-Extension Center
Tribune, Kansas Troy Dumler Former Ag
Economist, Research-Extension Center Garden
City, Kansas
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Objectives

• Determine effect of long-term tillage practices
  (1991-2012) in a wheat-sorghum-fallow rotation
  on
• - Soil water
• - Grain yield

Alan Schlegel Southwest Research-Extension Center
Tribune, Kansas
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WSF rotation

• Conventional tillage
• Reduced tillage
• No-till

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WSF, Tribune
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WSF, Tribune
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Weed control during fallow
Tillage Chemical
- - - - of operations - - - - - - - - of operations - - - -
CT 4-5 0
RT 2-3 2
NT 0 4
1991-2000
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Weed control during fallow
Tillage Chemical
- - - - of operations - - - - - - - - of operations - - - -
CT 4-5 0
RT 4-5 (W) 4 (S)
NT 0 4
2001 thru current
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WSF, Tribune, 1991-2010
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WSF, Tribune
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Tribune Wheat Yields in WSF Rotation
NT vs CT 22gt 1991-2000 61gt 2001-2010. NT vs
RT 9gt 1991-2000 32gt 2001-2010.
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WSF, Tribune, 1991-2010
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WSF, Tribune
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Tribune Sorghum Yields in WSF Rotation
NT vs CT 71gt 1991-2000 256gt 2001-2010. NT
vs RT 10gt 1991-2000 119gt 2001-2010.
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Summary (2001-2010)

• Available soil water at planting 1.5 inches
  greater with RT/NT than CT.
• Grain yield wheat NT 50 greater than CT
  30 greater than RT sorghum NT
  3X greater than CT
• 2X greater than RT

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Cost of Production
Tillage Wheat Sorghum
CT 82.09 98.76
RT 82.88 117.19
NT 98.72 120.46
Input costs do not include harvest costs which
vary with yield.
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Sorghum Costs
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Wheat Costs
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Tribune Tillage Study
2010-2011 market year average price (5.50,
4.85) and costs.
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Questions?