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Plant Growth Modeling: Tools for Analysis and Management

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Single factors are generally less important than interactions between factors. ... Soybean Cyst Nematodes (SCN) Weeds. Water Stress ... – PowerPoint PPT presentation

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Title: Plant Growth Modeling: Tools for Analysis and Management


1
Plant Growth ModelingTools for Analysis and
Management
2
Types of Yield Limiting Factors
  • Landscape
  • Soil Physical Properties
  • Soil Chemical Properties
  • Biological Factors
  • Man-made Factors
  • Weather
  • Interactions of the above

3
From Fundamentals of Farming and Farm Life by E.
J. Kyle and A. C. Ellis, 1922.
4
YLF Interactions
  • Single factors are generally less important than
    interactions between factors.
  • Crop growth models are increasingly used to
    explain interactions.

5
YLF Precision Management?
  • Can we measure it?
  • Directly or indirectly?
  • Is it perennial or sporadic?
  • Can we change the factor or respond to it?
  • Is managing cost effective?

6
Definition
Modeling is the use of mathematical, logical or
experiential relationships to predict the status
of an organism or system in response to changing
conditions.
7
Models are used for
  • Strategic decisions (what mix of crops to plant)
  • Tactical planning (when to spray)
  • Logistics (allocation of resources)
  • Operational decisions (how much to apply)

8
Plant Growth Modeling
  • Simple regression
  • Multi-variable empirical
  • Rule-based
  • Mechanistic

9
Temporal Variability Focus
  • Crop models will be used to understand the
    interactions between crop parameters

10
Site-Specific Modeling
  • Determining cause and effect on yield variability
  • Ex Paz, et al, 1998
  • Management of temporal variability
  • Ex Gossym-Comax

11
Why Do Soybean Yields VaryA Case Study of the
McGarvey Field
  • Location Perry, Iowa
  • 100 grids
  • Grid size 0.2 hectare
  • Yield, SCN egg count, weeds, soil properties,
    plant population
  • Only 77 grids had 3 years of yield data

12
Yield Limiting Factors
Soybean Cyst Nematodes (SCN) Weeds Water Stress
Theory exists for modeling SCN and weeds, but
water stress is the unknown factor
13
Agronomic Soil Weather
Simulated Annealing
SCN
FLDSKsatRHRF
Crop Model
Set parameter value
RMSEminimized?
Yield
No
Yes
Weed Loss
Yield Optimized Parameters
14
McGarvey Field Soybean Calibration
15
Yield Potential for 1997
Maximum potential yield
Actual Yield
Difference Water Stress, SCN, weeds
16
Turn Water Stress Off
Maximum potential yield
Actual yield
Water StressEffect
17
Turn SCN Off
Maximum potential yield
Actual yield
SCN Effect
18
Turn Weed Effect Off
Maximum potential yield
Actual yield
Weed Effect
19
Estimated Soybean Yield Loss (1997)
Stress Yield Loss kg/ha (bu/ac)
Water Stress 709 (10.7) SCN 119 (
1.8) Weeds 20 ( 0.3) All stress 941 (14.2
) Interactions 93 ( 1.4)
20
Gossym-Comax
  • Cotton growth model based on plant physiology and
    soil water and chemical processes
  • Use of actual and historic weather data provides
    what if scenario evaluation

21
Cotton Growth Models
  • GOSSYM
  • CPM
  • Cotton2K
  • COTONS
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