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

Winter Wheat Nielsen et al.

What is Plant Available Water?

PSE = Interval Precip SW end – SW beg PSE – Precipitation Storage Efficiency Soil water retained + Precipitation stored during the fallow period

How do you measure Water Use? Water Use = Soil Water Change + Precipitation + Irrigation - Runoff - Deep Percolation

How do you measure Water 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 (Tribune, KS) Schlegel et al.

Vigil et al. 2012

Nielsen, et al. PSE During Fallow in W-F

Precipitation Storage Efficiency

Crop Choice Effect on Surface Residues and Fallow Efficiency Schlegel et al.

Wheat Residue: Soil water storage & Grain Sorghum Yield

Time of Year: Efficiency from Row-Crop Harvest to Wheat Seeding (W-S-F) 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 Results Garden City, KS Average Precipitation ( ) = in Average Precipitation ( ) = in Average Precipitation ( ) = in

Kansas Annual Precipitation, Source: K-State Weather Data Library in 484 mm in 615 mm in 352 mm in 1272 mm in 1140 mm in 1009 mm in 878 mm in 746 mm

Flex-Fallow Treatments (Cover, Forage, Grain) SeasonCropYear Produced WinterYellow sweet cloverxx ""Yellow sweet clover/Winter triticalex ""Hairy vetchxxxxx ""Hairy vetch/Winter triticalexxxx ""Winter lentilxxx ""Winter lentil/Winter triticalexxx ""Winter peaxxxxx ""Winter pea/Winter triticalexxxx ""Winter triticalexxxxx ""Winter pea (grain)xxx SpringSpring lentilxxxxx ""Spring lentil/Spring triticalexxxx ""Spring peaxxxxx ""Spring pea/Spring triticalexxxx ""Spring triticalexxxx ""Spring pea (grain)xx OtherChem-fallowxxxxx ""Continuous winter wheatxxxxx

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 >0.8 inches than hay (0-6 ft)

PAW at Wheat Planting-Fallow Method ( )

Yield Results 2 good years, 2 very poor years Cover Crop vs Hay Crop no effect

Economic Results

Economic Results Summary ReturnWinterSpringNone Vetch Vetch /TritLentil Lentil /TritPea Pea /TritTritWheatLentil Lentil /TritPea Pea /TritTrit Pea, grainFallow Cover crop Hay Grain only Best alternative Fallow costs $48/A Returns include any reduction of following wheat yield Winter 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? CropHayCoverGrain Fallow Spring peax Spring pea/Spring oatxx Spring pea/Spring triticalexx Spring oatxx Spring triticalex Yellow sweet clover (planted with sorghum)xx Daikon radish (planted with wheat)x Shogoin turnip (planted with wheat)x Cocktail mixxx (oat, triticale, pea, buckwheat, forage brassica & forage radish)

PAW at Wheat Planting-Fallow Method ( )

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 < 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?

Results Spring triticale forage –4 years of no yield impact & 1 year yield reduced –2008, 2009, 2010, & 2011 no impact – bu –On average wheat yield -2.5 to 5 bu/A (range: +2 to -24) –1 ton $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 $7.00/bu –Wheat-fallow yield potential of <25 bu requires fallow

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

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

Objectives Determine effect of long-term tillage practices ( ) in a wheat- sorghum-fallow rotation on: - Soil water - Grain yield Alan Schlegel Southwest Research-Extension Center – Tribune, Kansas

WSF rotation  Conventional tillage  Reduced tillage  No-till

WSF, Tribune

Weed control during fallow TillageChemical # of operations CT4-50 RT2-32 NT

Weed control during fallow TillageChemical # of operations CT4-50 RT4-5 (W)4 (S) NT thru current

WSF, Tribune,

WSF, Tribune

Tribune Wheat Yields in WSF Rotation NT vs CT: 22%> & 61%> NT vs RT: 9%> & 32%>

WSF, Tribune,

WSF, Tribune

Tribune Sorghum Yields in WSF Rotation NT vs CT: 71%> & 256%> NT vs RT: 10%> & 119%>

Summary ( ) 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

Cost of Production TillageWheatSorghum CT$82.09$98.76 RT$82.88$ NT$98.72$ * Input costs do not include harvest costs which vary with yield.

Sorghum Costs

Wheat Costs

Tribune Tillage Study market year average price ($5.50, $4.85) and costs.

Questions?