Shallow groundwater impacts on corn biophysics and yield during a drought. Sam Zipper Steve Loheide wsc.limnology.wisc.edu

Transcription

1 Shallow groundwater impacts on corn biophysics and yield during a drought Sam Zipper Steve Loheide wsc.limnology.wisc.edu

2 Research Objectives 1. Identify major corn physiological responses to water stress during 2012 drought 2. Contextualize physiological responses in terms of groundwater availability 3. Quantify yield losses as a result of water stress 4. Calculate groundwater subsidy provided to corn from shallow water table

3 Water stress impacts on corn Study site GW & Soil Conditions Physiological response Micro level stomatal conductance Macro level leaf area index Yield response Pollination success Grain yield Groundwater subsidy

4 vegetative pollination grain filling

5 vegetative pollination grain filling Spring: Warm weather, normal Y.T.D. precipitation, optimistic farmers

6 vegetative pollination grain filling July 9: <8 mm precipitation since June 1

7 vegetative pollination grain filling July 18-20: 50 mm rain but it came too late

8 vegetative pollination grain filling Late July, August, September: ~Normal rains, but didn t help

9 vegetative Water Stress Reduced Biomass decreased root & shoot growth decreased nutrient uptake smaller cob size

10 pollination Water Stress Reduced Grain Yield decreased pollination success lower kernel counts shorter cobs

11 grain filling Water Stress Reduced Grain Yield & Biomass reduced kernel mass more frequent kernel abortion higher risk for pests

12 Watershed Subbasins Internally drained Imagery: Landsat ( ) Delineation: Eric Booth

13 Measurements -GW elevation -Stomatal conductance -Leaf area index -Total biomass -Grain mass -Kernel count, kernel mass, etc. Elevation [m] Well Soil moisture station Transect site (no well) Biophysical Transect

14 Measurements -GW elevation -Stomatal conductance -Leaf area index -Total biomass -Grain mass -Kernel count, kernel mass, etc. Elevation [m] Well Soil moisture station Transect site (no well) Biophysical Transect

15 Measurements -GW elevation -Stomatal conductance -Leaf area index -Total biomass -Grain mass -Kernel count, kernel mass, etc. Elevation [m] Well Soil moisture station Transect site (no well) Biophysical Transect

16 Well silt loam Soil moisture station Transect site (no well) Biophysical Transect silt loam silt loam silty clay loam silt loam silt loam silt loam loam Soil data from DATCP Image from NAIP (2010)

17 Well silt loam Soil moisture station Transect site (no well) Biophysical Transect silt loam silt loam silty clay loam silt loam silt loam silt loam loam Soil data from DATCP Image from NAIP (2010)

18 vegetative pollination grain filling

19 600 Stomatal Conductance [mmol m -2 s -1 ] Measure of how easily water, CO2 can enter/leave a plant Higher stomatal conductance higher transpiration, photosynthesis Water stress reduced stomatal conductance reduced photosynthesis 600 Shallow GW Medium GW Deep GW /24 6/7 6/21 7/5 7/19 8/2 8/16 8/30 5/24 6/7 6/21 7/5 7/19 8/2 8/16 8/30 5/24 6/7 6/21 7/5 7/19 8/2 8/16 8/30 0 Stomata Image:

20 800 Stomatal Conductance [mmol m -2 s -1 ] /16 5/24 6/7 6/21 7/5 7/19 8/2 8/16 8/30 5/24 6/7 6/21 7/5 7/19 8/2 8/16 8/30 5/24 6/7 6/21 7/5 7/19 8/2 8/30 WATER STRESS Shallow GW Medium GW Deep GW

21 Leaf Area Index = surface area leaves surface area ground

22 Leaf Area Index = surface area leaves surface area ground 6% 15% 18%

23 Leaf Area Index = surface area leaves surface area ground 6%

24 Stomatal Conductance Micro Scale Decrease in stomatal conductance during drought at all sites Larger and longer decrease at deep GW site than shallow GW site Leaf Area Index Macro Scale Decrease in LAI at all sites due to leaf wilting/rolling Magnitude of decrease correlated with GW depth

25 -66% -76% Shallow Medium Deep

26 -13% -69% -93% 2010 County Average Shallow Medium 2012 Data Deep Image source: rawlingsbrokeragecompany.com

27 -13% -69% -93% Lowry & Loheide (2010), WRR: Additional plant water use in the presence of shallow groundwater, as compared to free drainage conditions 2010 County Average Shallow Medium Deep 2012 Data GW Subsidy = WU GW WU FD Image source: rawlingsbrokeragecompany.com

28 101 bu 142 bu Lowry & Loheide (2010), WRR: Additional plant water use in the presence of shallow groundwater, as compared to free drainage conditions 2010 County Average Shallow Medium Deep 2012 Data GW Subsidy = WU GW WU FD GW Subsidy = (Yield GW Yield FD )/WUE Corn Grain WUE = 0.55 bu/mm (FAO TR07) Image source: rawlingsbrokeragecompany.com

29 101 bu = 184 mm 142 bu = 258 mm Lowry & Loheide (2010), WRR: Additional plant water use in the presence of shallow groundwater, as compared to free drainage conditions 2010 County Average Shallow Medium Deep 2012 Data GW Subsidy = WU GW WU FD GW Subsidy = (Yield GW Yield FD )/WUE Corn Grain WUE = 0.55 bu/mm (FAO TR07) GW Subsidy = mm Image source: rawlingsbrokeragecompany.com

30 101 bu = 184 mm 142 bu = 258 mm Lowry & Loheide (2010), WRR: Additional plant water use in the presence of shallow groundwater, as compared to free drainage conditions 2010 County Average Shallow Medium Deep 2012 Data GW Subsidy = WU GW WU FD GW Subsidy = (Yield GW Yield FD )/WUE Corn Grain WUE = 0.55 bu/mm (FAO TR07) GW Subsidy = mm Corn Biomass WUE = 3.3 kg/m 3 (UW-Ex) GW Subsidy = up to 148 mm GW Subsidy = ~ mm 18-30% mean annual precipitation 28-47% mean annual ET Image source: rawlingsbrokeragecompany.com

31 1. Identify major corn physiological responses to water stress during 2012 drought 2. Contextualize physiological responses in terms of groundwater availability 3. Quantify yield losses as a result of water stress 4. Calculate groundwater subsidy provided to corn from shallow water table

32 1. Identify major corn physiological responses to water stress during 2012 drought Reduced stomatal conductance rates Reduced LAI Mistimed pollen release Reduced transpiration, photosynthesis 2. Contextualize physiological responses in terms of groundwater availability 3. Quantify yield losses as a result of water stress 4. Calculate groundwater subsidy provided to corn from shallow water table

33 1. Identify major corn physiological responses to water stress during 2012 drought Reduced stomatal conductance rates Reduced LAI Mistimed pollen release Reduced transpiration, photosynthesis 2. Contextualize physiological responses in terms of groundwater availability More extreme physiological response at deeper GW sites 3. Quantify yield losses as a result of water stress 4. Calculate groundwater subsidy provided to corn from shallow water table

34 1. Identify major corn physiological responses to water stress during 2012 drought Reduced stomatal conductance rates Reduced LAI Mistimed pollen release Reduced transpiration, photosynthesis 2. Contextualize physiological responses in terms of groundwater availability More extreme physiological response at deeper GW sites 3. Quantify yield losses as a result of water stress Relative to 2010: bu/ac grain loss, 17.4 tons/ac silage loss Relative to shallow GW site: up to 92% grain loss, 79% silage loss 4. Calculate groundwater subsidy provided to corn from shallow water table

35 1. Identify major corn physiological responses to water stress during 2012 drought Reduced stomatal conductance rates Reduced LAI Mistimed pollen release Reduced transpiration, photosynthesis 2. Contextualize physiological responses in terms of groundwater availability More extreme physiological response at deeper GW sites 3. Quantify yield losses as a result of water stress Relative to 2010: bu/ac grain loss, 17.4 tons/ac silage loss Relative to shallow GW site: up to 92% grain loss, 79% silage loss 4. Calculate groundwater subsidy provided to corn from shallow water table Up to mm additional water provided by shallow GW 28-48% mean annual ET

36 1. Identify major corn physiological responses to water stress during 2012 drought Reduced stomatal conductance rates Reduced LAI Mistimed pollen release Reduced transpiration, photosynthesis 2. Contextualize physiological responses in terms of groundwater availability More extreme physiological response at deeper GW sites 3. Quantify yield losses as a result of water stress Relative to 2010: bu/ac grain loss, 17.4 tons/ac silage loss Relative to shallow GW site: up to 92% grain loss, 79% silage loss 4. Calculate groundwater subsidy provided to corn from shallow water table Up to mm additional water provided by shallow GW 28-48% mean annual ET GW is an important resource for crop production!!

37 Questions? Funding: Tons of Help: Advice: NSF Grant DEB Anna Grant Birge Award Taylor Pomije Erin Gross Eric Booth Steve Loheide Chris Kucharik Gregg Sanford Other WSC/ WRE faculty, post-docs, students Field Help: Doug Brugger Erin Crabb Sean Gillon Emilio Medina Missy Motew Evren Soylu Carolyn Voter Nathan Wells Jiangxiao Xiu Joey & Tyler

38 800 Stomatal Conductance [mmol m -2 s -1 ] /16 5/24 6/7 6/21 7/5 7/19 8/2 8/16 8/30 5/24 6/7 6/21 7/5 7/19 8/2 8/16 8/30 5/24 6/7 6/21 7/5 7/19 8/2 8/30 WATER STRESS Shallow GW Medium GW Deep GW

39 Leaf Area Index = surface area leaves surface area ground 6% 15% 18%

40 101 bu = 184 mm 142 bu = 258 mm Lowry & Loheide (2010), WRR: Additional plant water use in the presence of shallow groundwater, as compared to free drainage conditions 2010 County Average Shallow Medium Deep 2012 Data GW Subsidy = WU GW WU FD GW Subsidy = (Yield GW Yield FD )/WUE Corn Grain WUE = 0.55 bu/mm (FAO TR07) GW Subsidy = mm Corn Biomass WUE = 3.3 kg/m 3 (UW-Ex) GW Subsidy = up to 148 mm GW Subsidy = ~ mm 18-30% mean annual precipitation 28-47% mean annual ET Image source: rawlingsbrokeragecompany.com

41 Results Silage & Grain Yields +17% -13% -69% -93% -40% -76% 2010 County Average Shallow Medium 2012 Data Deep 2010 County Average Shallow Medium Deep 2012 Data Image source: lifeonadairy.blogspot.com Image source: rawlingsbrokeragecompany.com

42 Well silt loam Soil moisture station Transect site (no well) Biophysical Transect silt loam silt loam silty clay loam silt loam silt loam silt loam loam Soil data from DATCP Image from NAIP (2010)

43 Study Site Measurements -GW elevation -Stomatal conductance -Leaf area index -Total biomass -Grain mass -Kernel count, kernel mass, etc. Well Soil moisture station Transect site (no well) Biophysical Transect