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W. Adam Sigler The Big Levers - Management, Soils, and Weather W. Adam Sigler The Big Levers - Management, Soils, and Weather

W. Adam Sigler The Big Levers - Management, Soils, and Weather - PowerPoint Presentation

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W. Adam Sigler The Big Levers - Management, Soils, and Weather - PPT Presentation

Interactions controlling soil water and nitrate loss in a nonirrigated cropping system MT AWRA October 19 th 2018 Funding USDANIFA National Integrated Water Quality Program MSU College of Agriculture ID: 783393

fallow water management crop water fallow crop management nitrate soils year leaching weather soil percolation model sigler tof deep

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Slide1

W. Adam Sigler

The Big Levers - Management, Soils, and Weather

Interactions controlling soil water and nitrate loss in a non-irrigated cropping system

MT AWRA; October 19th, 2018

FundingUSDA/NIFA National Integrated Water Quality ProgramMSU College of AgricultureMSU Office of the Vice President of ResearchMontana EPSCoRMSU Extension Water QualityMontana Fertilizer Advisory Committee

Stephanie A. EwingClain A. JonesRobert A. PaynMarco Maneta Perry Miller

Primary Field Technicians

Simon Fordyce

Kyle Mehrens

Robby Robertson, MSU/BSWC

Slide2

Judith Basin Nitrogen Project

M1 Nitrate-N

Broader Project Goals

To better understand the

sources

of nitrates in ground and surface water

To evaluate which

management practices

are likely to be effective to reduce nitrate leaching and to be adopted

To engage the local community in

participatory

research to meet the first two goals

Today’s Talk

How do agricultural management, weather, and soils interact to control deep percolation and nitrate leaching?

Slide3

Acknowledgments

Producer ResearchAdvisory Group

Nita BronecGreg GroveJim Kulish

Dave LinkerBrandon MorrisBing VonBergen

Advisory CommitteeTom Butcher: Producer, Fergus County

Rick Caquelin : MT NRCS, Central MT Region Range SpecialistChrissy Cook: MSU Extension, Judith Basin CountyDarren Crawford: MSU Extension, Fergus CountyPatricia Creamer: MT NRCS, Judith Basin Dist. Conservationist Pat Hensleigh: Montana NRCS, State Agronomist, Bozeman Curtis Hershberger: Producer and owner of NGS Sales, Denton Jane Holzer: Montana Salinity Control AssociationMark McLendon: NRCS Soil Conservationist, Lewistown Terry Metcalfe: Producer, Benchland Deen L. Pomeroy, RS: Central Montana Health DistrictKen Ronish: Fergus County Commissioner, Denton David Wichman: CARC, Superintendent and Agronomist

PublicationsJackson-Smith D, Ewing S A, Jones. C A, Sigler W A and Armstrong A (in press) The road less travelled: Assessing the impacts of in-depth farmer and stakeholder participation in groundwater nitrate pollution research. J. Soil Water Conserv.John, A.A., Jones, C.A., Ewing, S.A., Sigler, W.A., Bekkerman, A., Miller, P.R., 2017. Fallow replacement and alternative nitrogen management for reducing nitrate leaching in a semiarid region. Nutr. Cycl. Agroecosystems 1–18.Sigler, W.A., Ewing, S.A., Jones, C.A.,

Payn

, R.A., Brookshire, E.N.J., Klassen, J.K., Jackson-Smith, D., Weissmann, G.S., 2018. Connections among soil, ground, and surface water chemistries characterize nitrogen loss from an agricultural landscape in the upper Missouri River Basin. J.

Hydrol

. 556, 247–261.

Slide4

Research Question

How do agricultural management, weather, and soils interact to control deep percolation and nitrate leaching?

Judith Watershed

Moccasin Terrace

Study Area

Field C

Slide5

Management

, Weather, Soils

High Leaching Risk

Grower Standard Practice is a three year rotation

Year 1: Spring Grain

Year 2: Summer Fallow

Year 3: Winter Wheat

Year 4: Spring Grain

Year 5: Summer Fallow

Year 6: Winter Wheat

Bauder

et al. 1993

Chemical Summer Fallow = plant growth suppressed for a full year with herbicide

Slide6

Management

, Weather, Soils

Crop

Crop

Fallow

Crop Sequence CategoriesFallow-Crop-Crop-(FC)(CC)(CF)

Slide7

Management,

Weather, Soils

Seasonal Variation in Precipitation and Reference Potential Evapotranspiration

Slide8

Management, Weather,

Soils

North Catchment

South Catchment

(

ToF ~ 61 cm)(ToF ~ 131 cm)Thickness of Fines (ToF)

Slide9

Management, Weather,

Soils

Field C

Slide10

Richards Equation

Richards

Eq is in terms of water pressure; for mass balance, we need to convert pressure to water content.

Input Precipitation

Potential EvaporationPotential TranspirationSoil horizon hydro param (van Genuchten)OutputSoil moisture content

Water fluxHydrus 1D – Water movement through variably saturated soilvan Genuchten Equation Parameters (to implement Richards)

Θr - residual soil water content (L3/L3)Θs - saturated soil water content (L3/L3)α - corresponding approximately to the inverse of air-entry matric potential or bubbling pressure (1/L)n – pore size distribution index (dimensionless)Ks – saturated hydraulic conductivity (L/T)l – pore connectivity/tortuosity parameter (dimensionless), assumed to be 0.5 by Mualem 1976

Slide11

Model Soil Configuration

Gravel (sand) van

Genuchten

Θ

r = 0.05 (L3/L3)

Θs = 0.37 (L3/L3)α = 0.04 (1/L)n = 3.2 (dimensionless)Ks = 640 (L/T)

Fines (clay loam) van GenuchtenΘr = 0.08 (L3/L3)Θs = 0.44 (L3/L3)α = 0.02 (1/L)n = 1.41 (dimensionless)Ks = 8.18 (L/T)

Slide12

Model Calibration

Slide13

Modeling to Address Research Question

Period of available

Agrimet data

Management

(3 rotation scenarios)Weather

(15 years)Soils(30 depth increments)= 90 model scenarios for 3 year rotations with fallow over variable ToF

Slide14

Modeled Precipitation Partitioning by Crop Sequence Category

Evaporation

Transpiration

Deep Percolation

Storage

Each bar is the mean of 15 years of model results

Slide15

Nitrate Concentration by Crop Sequence

Nitrate Sources

Fertilizer:

Mineralization:

HighHigh

HighLow0High

Slide16

Model Results by Crop Sequence Category

Deep Percolation (cm yr

-1)

Slide17

Field C

Model Results

ToF

% field

With Fallow

Without FallowOverallFCCCCF

CC0-5552.86.55.93

10.6

3

>55

47.2

2.8

1.9

0.5

5.9

0.5

ToF

% field

With Fallow

Without Fallow

Overall

F

C

C

C

C

F

C

C

0-55

52.8

4.9

3

2.7

9.1

2.7

>55

47.2

2.2

1

0.4

5

0.5

Modeled Deep Percolation (cm yr

-1

)

Modeled Nitrate Leaching (kg N ha

-1

yr

-1

)

Preliminary Results

Slide18

Catchment Scale Model Results

North Catchment

Landscape Scale Sigler et al. 2018

Current Soil Modelling

Deep Percolation (cm yr-1

)5.41.9Nitrate Leaching(kg N ha-1 yr-1)11.12.5South CatchmentLandscape Scale Sigler et al. 2018Current Soil ModelingDeep Percolation (cm yr-1)8.72.2

Nitrate Leaching(kg N ha-1 yr-1)18.42.8Preliminary Results

Slide19

Precipitation

Fallow-

Crop

Crop-

Crop

Crop-FallowSoils

ManagementToF = 55Leaching risk is highest during fallow and post-fallow periodsToF <40cm soils contribute disproportionately to leachingHeavy precip yrs dominate mean 15 year leaching ratesConclusions