Soil Moisture: Managing a Limited Resource Wisely

John Holman, PhD

Cropping Systems Agronomist

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– 30’s, 50’s, and Today

Available Water at Planting (in)0 2 4 6 8 10

Yiel

d (b

u/a)

010203040506070

bu/a = 5.56 + 5.34*inr2 = 0.76

Winter WheatWinter Wheat

Nielsen et al.

What is Plant Available Water?

Soil Textural Class Available Water (in/ft)Coarse Sand 0.25-0.75Fine Sand 0.75-1.00Loamy Sand 1.10-1.20Sandy Loam 1.25-1.40Fine Sandy Loam 1.50-2.00Silt Loam 2.00-2.50Silty Clay Loam 1.80-2.00Silty Clay 1.50-1.70Clay 1.20-1.50

Klocke, N and G. Hergert. 1990. How soil holds water.NebGuide G90-964. University of Nebraska, Lincoln.

PSE = Interval PrecipSWend – SWbeg

PSE – Precipitation Storage Efficiency

• Soil water retained + Precipitation stored during the fallow period

How do you measureWater Use?

Water Use = Soil Water Change+ Precipitation+ Irrigation- Runoff- Deep Percolation

How do you measureWater Use?

Water Use = Soil Water Change+ Precipitation+ Irrigation- Runoff- Deep Percolation

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

Effect of Tillage – W-F 1993-1998 (Tribune, KS)

Fallow Method

No-Till 16.0 (6.30) a 23.8 aReducted Till 14.0 (5.51) b 20.9 aConventional Till 8.2 (3.23) c 12.1 b

Source of VariationFallow Method 0.0114

LSD 0.05 1.6 1.7 0.07†Letters within a column represent differences at LSD (0.05)

FallowEfficiency

ANOVA P>F

0.011

cm (in)Accumulation

Percent

Schlegel et al.

Rate of water evap. first 2 days, & during the next 3 to 5 days

Tillage treatmentsMB-plow Sweep-ct Sweep-rt No-till

Rat

e of

wat

er lo

ss (i

nch/

day)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0-2 days after 3-5 days after

Vigil et al. 2012

Average

Fallow Period 1st Summer FWS 2nd Summer Entire Fallow

Prec

ipita

tion

Stor

age

Effic

ienc

y (%

)

0

20

40

60

80

CTNT

P<0.001

P<0.001

P<0.001

P=0.387

Wheat Fallow Systems1996-2006 Akron, CO

Nielsen, et al.

PSE During Fallow in W-F

Precipitation Storage Efficiency

Crop Choice Effect on Surface Residues and Fallow Efficiency

1998-2008

Fallow Method

W-S-F 8.3 (3.25) a 20.1 aW-SF-F 5.3 (2.08) b 12.5 b

Source of VariationFallow Method 0.0346

LSD 0.05 1.6 (1.14) 6.94†Letters within a column represent differences at LSD (0.05)

ANOVA P>F

0.0452

FallowAccumulation Efficiency

cm (in) Percent

Schlegel et al.

Bushland, TX (Unger, 1978)

Wheat Residue (lb/acre)0 2000 4000 6000 8000 10000 12000

Wat

er S

tora

ge (i

n)

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

Gra

in S

orgh

um Y

ield

(lb/

a)

1000

1500

2000

2500

3000

3500

4000Water StorageYield

Wheat Residue: Soil water storage & Grain Sorghum Yield

Time of Year: Efficiency from Row-Crop Harvest to

Wheat Seeding (W-S-F)

SWREC-Tribune 2001-2007

Time Period Efficiency

PercentRow-Crop Harvest to July Fallow 28.8July Fallow to Wheat Planting -4.6Row-Crop Harvest to Wheat Planting 21.2

Schlegel et al.

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.

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?

Western Kansas Flex-Fallow ResultsGarden City, KS

Average Precipitation (1908-2012) = 18.22 inAverage Precipitation (2008-2012) = 15.75 inAverage Precipitation (2010-2012) = 13.33 in

Kansas Annual Precipitation, 1971-2000

Source: K-State Weather Data Library -- www.oznet.ksu.edu/wdl

19.04 in484 mm

24.21 in615 mm

13.87 in352 mm

50.06 in1272 mm

44.89 in1140 mm

39.72 in1009 mm

34.55 in878 mm

29.38 in746 mm

Flex-Fallow Treatments (Cover, Forage, Grain)Season Crop Year Produced

2007 2008 2009 2010 2011Winter 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 xSpring 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 xOther Chem-fallow x x x x x"" Continuous winter wheat x x x x x

Cover and Forage Crop Termination

Winter Peas

Winter terminated ~May 15 (winter triticale heads)

Spring terminated ~June 1 (spring triticale heads)

Plots split: ½ hayed & ½ sprayed out and left standing

Plant Available Water at Wheat Planting:Standing Cover Crop vs Hay

Cover Crop Method

Cover 0.09 a† 5.76 aHay 0.06 b 4.96 b

Source of Variation

LSD 0.05 0.03 0.45†Letters within a column represent differences at LSD 0.05

Plant Available Water (0-6 ft)(in)

<0.0001

Plant Available Water (0-3 in)(in)

ANOVA P>F

<0.001

• Cover >0.8 inches than hay (0-6 ft)

PAW at Wheat Planting-Fallow Method (2008-12)Fallow Method Difference from Fallow

(in)Fallow 7.91 a 0.00Hairy Vetch 6.24 b -1.68S Pea 6.16 b -1.75W Lentil 6.06 bc -1.85S Lentil 5.68 bcd -2.24S Triticale 5.49 bcd -2.43W Pea 5.40 bcd -2.51S Pea/S Triticale 5.24 cde -2.68S Lentil/S Triticale 5.17 cdef -2.75Hairy Vetch/W Triticale 5.15 def -2.76W Pea/W Triticale 4.95 defg -2.97W Lentil/W Triticale 4.49 efg -3.42W Triticale 4.29 fg -3.62Pea (grain) 4.09 gh -3.82W Wheat 3.28 h -4.64LSD 0.05 0.90

Plant Available Water (0-6 ft)(in)

2009-2012 Yield Results

2 good years, 2 very poor yearsCover Crop vs Hay Crop no effect

Economic ResultsNone

VetchVetch/

Trit LentilLentil/

Trit PeaPea/Trit Trit Wheat Lentil

Lentil/Trit Pea

Pea/Trit Trit

Pea, grain Fallow

ExpensesTotal seeding cost $/A 69 48 24 26 37 32 27 21 23 26 40 35 30 40 0

Total hay cost $/A 19 64 17 60 21 65 64 0 19 36 33 41 39 0 0

Grain harvesting $/A 0 0 0 0 0 0 0 30 0 0 0 0 0 30 0

Fallow spray cost $/A 36 36 36 36 36 36 36 36 36 36 36 36 36 36 48

In-crop spray cost $/A 0 0 0 0 0 0 0 11 0 0 0 0 0 11 0Total Expense (cover) 104 83 60 61 73 68 63 - 59 62 76 71 66 - -Total Expense (hay) 123 148 77 121 94 133 126 - 78 98 109 111 104 - -Total Expense (grain) - - - - - - - 98 - - - - - 117 48

ReturnsYield ton/A or bu/A 0.2 2.2 0.2 2.0 0.3 2.2 2.2 33.0 0.3 1.0 0.8 1.2 1.1 14.0 0.0Price $/ton or $/bu 110 110 110 110 110 110 110 7 110 110 110 110 110 7 0Yield Return $/A 25 240 17 219 36 243 238 216 30 105 93 130 121 92 0

N Return $/A 20 20 20 20 20 20 0 0 20 20 20 20 0 0 0

Impact on wheat bu/A -4 -9 -2 -9 -6 -12 -9 -22 -3 -7 -6 -8 -5 -12 0Impact on wheat $/A -26 -59 -13 -59 -39 -78 -59 -144 -20 -46 -39 -52 -33 -78 0

Net Return (cover) -111 -122 -53 -100 -92 -126 -121 - -58 -88 -95 -103 -98 - -Net Return (hay) -124 9 -73 14 -97 7 28 - -68 -51 -55 -47 -29 - -Net Return (grain) - - - - - - - -46 - - - - - -38 -48Net Return (alt vs fallow) -76 56 -25 61 -50 55 75 2 -20 -3 -8 1 19 10

*Assumption: N contribution from legume 0 when hayed, 50 lbs N add for winter trit, and 25 lbs N add for spring trit.

Winter Spring

Economic Results Summary

Return Winter Spring None

VetchVetch/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/AReturns include any reduction of following wheat yieldWinter and spring triticale hay, grain peas, cont. wheat

New Study (W-S-F)Spring oat versus triticale?

Radish or turnip planted with wheat ?

Clover planted with sorghum?

Cocktail mixes?Crop Hay Cover GrainFallowSpring pea xSpring pea/Spring oat x xSpring pea/Spring triticale x xSpring oat x xSpring triticale xYellow sweet clover (planted with sorghum) x xDaikon radish (planted with wheat) xShogoin turnip (planted with wheat) xCocktail mix x x (oat, triticale, pea, buckwheat, forage brassica & forage radish)

PAW at Wheat Planting-Fallow Method (2012-13)Fallow Method Difference from Fallow

(in)Fallow 6.38 a 0.00Spring Pea (grain) 3.26 b -3.12Spring Pea 3.04 b -3.34Spring Oat 2.77 bc -3.61Spring Pea/Triticale 2.61 bc -3.77Spring Triticale 2.04 bc -4.33Spring Peat/Oat 2.03 bc -4.35Cocktail* 1.95 bc -4.42Safflower 1.11 c -5.27LSD 0.05 1.90*Cocktail (oat, triticale, pea, buckwheat, forage brassica, & forage radish)

Plant Available Water (0-6 ft)(in)

ResultsImpact 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 < 3 bu & winter crops < 6 bu

– 2012: second dry year (WF yielded 32 bu/A)

– Spring crops < 23 bu & winter crops < 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?

ResultsSpring 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 @ $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 @ $7.00/bu

– Wheat-fallow yield potential of <25 bu requires fallow

ConclusionIt 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

Reducing Fallow and Tillage in Dryland Cropping Systems

Alan SchlegelSouthwest Research-Extension Center – Tribune, Kansas

Troy DumlerFormer Ag Economist, Research-Extension Center – Garden City, Kansas

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

WSF rotationConventional tillage

Reduced tillage

No-till

WSF, Tribune

0

5

10

15

20

Prec

ip.,

inch

1991 1994 1997 2000 2003 2006 2009

Year

In-Season Precipitation - Sorghum

WSF, Tribune

Weed control during fallow

Tillage Chemical

- - - - # of operations - - - -

CT 4-5 0

RT 2-3 2

NT 0 4

1991-2000

Weed control during fallow

Tillage Chemical

- - - - # of operations - - - -

CT 4-5 0

RT 4-5 (W) 4 (S)

NT 0 4

2001 thru current

Available Soil Water at Wheat Planting

0

2

4

6

8

10

CT RT NTTillage

ASW

, inc

h

WSF, Tribune, 1991-2010

WSF, Tribune

Tribune Wheat Yields in WSF Rotation

NT vs CT: 22%> 1991-2000 & 61%> 2001-2010.

NT vs RT: 9%> 1991-2000 & 32%> 2001-2010.

Available Soil Water at Sorghum Planting

012345678

CT RT NTTillage

ASW

, inc

h

WSF, Tribune, 1991-2010

WSF, Tribune

Tribune Sorghum Yields in WSF Rotation

NT vs CT: 71%> 1991-2000 & 256%> 2001-2010.

NT vs RT: 10%> 1991-2000 & 119%> 2001-2010.

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

TRIBUNE 1974-2004Y = -27.3 + 3.78X

n = 253 r2 = 0.638 RMSE = 10.7 P<0.0001

WATER SUPPLY: ASW + PRECIP. (in.)0 5 10 15 20 25 30

WH

EA

T G

RA

IN

(bu/

acre

)

0

20

40

60

80

100

CONVENTIONAL TILLAGEY = -19.9 + 3.24X

n = 75 r2 = 0.651 RMSE = 8.84 P<0.0001

WIN

TER

WH

EA

T G

RA

IN

(bu/

acre

)

0

20

40

60

80

100TRIBUNE1974-2004

A

NO TILLAGEY = -56.4 + 5.20X

n = 64 r2 = 0.831 RMSE = 8.79 P<0.0001

WATER SUPPLY: ASW + PRECIP. (in.)4 8 12 16 20 24 28

0

20

40

60

80

100

B

TRIBUNE 1973-2003Y = -35.9 + 6.70X

n = 142 r2 = 0.595 RMSE = 21.7 P<0.0001

WATER SUPPLY: ASW + PRECIP. (in.)0 5 10 15 20 25

SO

RG

HU

M G

RA

IN

(bu/

acre

)

0

20

40

60

80

100

120

140

160

180

CONVENTIONAL TILLAGEY = -20.9 + 5.22X

n = 59 r2 = 0.409 RMSE = 22.11 P<0.0001

SO

RG

HU

M G

RA

IN

(bu/

acre

)

0

20

40

60

80

100

120

140

160

180TRIBUNE1973-2003

A

NO TILLAGEY = -46.0 + 7.45X

n = 28 r2 = 0.834 RMSE = 14.94 P<0.0001

WATER SUPPLY: ASW + PRECIP. (in.)0 4 8 12 16 20 24

0

20

40

60

80

100

120

140

160

180

B

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.

Sorghum Costs

MiloCT CT CT RT RT RT NT NT NT

Rate Price Total Rate Price Total Rate Price TotalSeed 3 2.87 8.61 3 2.87 8.61 3 2.87 8.61Fertilizer

N 45 0.24 10.80 50 0.39 19.50 55 0.39 21.45P 20 0.44 8.80 22 0.44 9.68 25 0.44 11.00

HerbicideBiceplite II Mag 1.5 13.43 20.15 1.5 13.43 20.15 1.5 13.43 20.15RT3 0 0.40 0.00 22 0.20 4.40 22 0.20 4.402,4-D 0 0.20 0.00 2 3.10 6.20 2 3.10 6.20Atrazine 0 2.62 0.00 51 0.15 7.65 51 0.15 7.65Glyphosate 0.00 32 0.12 3.84 32 0.12 3.84Glyphosate 0.00 32 0.12 3.84 32 0.12 3.84Glyphosate 0.00 0.00 0.00herb 0.00 0.00 0.00herb 0.00 0.00 0.00herb 0.00 0.00 0.00

MachinerySweep 3 7.42 22.26 0 7.42 0.00 0 7.42 0.00NH3 appl 1 10.55 10.55 0 10.55 0.00 0 10.55 0.00D/L Fert 0 4.75 0.00 1 4.75 4.75 1 4.75 4.75Herbicide 1 4.98 4.98 3 4.98 14.94 3 4.98 14.94Plant 1 12.61 12.61 1 13.63 13.63 1 13.63 13.63

Total 98.76 117.19 120.46

Wheat Costs

WheatCT CT CT RT RT RT NT NT NT

Rate Price Total Rate Price Total Rate Price TotalSeed 50 0.13 6.50 50 0.13 6.50 50 0.13 6.50Fertilizer

N 40 0.24 9.60 45 0.24 10.80 50 0.39 19.50P 15 0.44 6.60 17 0.44 7.48 20 0.44 8.80

HerbicideAlly 0.1 13.21 1.32 0.1 13.21 1.32 0.1 13.21 1.32Banvel 4 0.43 1.72 4 0.43 1.72 4 0.43 1.72RT3 0 0.20 0.00 16.5 0.20 3.30 16.5 0.20 3.302,4-D 0 3.10 0.00 1 3.10 3.10 1 3.10 3.10Glyphosate 0.00 0.00 32 0.12 3.84Glyphosate 0.00 0.00 32 0.12 3.84Glyphosate 0.00 0.00 32 0.12 3.84herb 0.00 0.00 0.00herb 0.00 0.00 0.00herb 0.00 0.00 0.00

MachinerySweep 4 7.42 29.68 2 7.42 14.84 0 0.00 0.00NH3 appl 1 10.55 10.55 1 10.55 10.55 0 10.55 0.00D/L Fert 0 4.75 0.00 0 4.75 0.00 1 4.75 4.75Herbicide 1 4.98 4.98 2 4.98 9.96 5 4.98 24.90Plant 1 11.14 11.14 1 13.31 13.31 1 13.31 13.31

Total 82.09 82.88 98.72

Tribune Tillage Study

2010-2011 market year average price ($5.50, $4.85) and costs.

Questions?