Title: Plant Growth Modeling: Tools for Analysis and Management
1Plant Growth ModelingTools for Analysis and
Management
2Types of Yield Limiting Factors
- Landscape
- Soil Physical Properties
- Soil Chemical Properties
- Biological Factors
- Man-made Factors
- Weather
- Interactions of the above
3From Fundamentals of Farming and Farm Life by E.
J. Kyle and A. C. Ellis, 1922.
4YLF Interactions
- Single factors are generally less important than
interactions between factors. - Crop growth models are increasingly used to
explain interactions.
5YLF 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?
6Definition
Modeling is the use of mathematical, logical or
experiential relationships to predict the status
of an organism or system in response to changing
conditions.
7Models 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)
8Plant Growth Modeling
- Simple regression
- Multi-variable empirical
- Rule-based
- Mechanistic
9Temporal Variability Focus
- Crop models will be used to understand the
interactions between crop parameters
10Site-Specific Modeling
- Determining cause and effect on yield variability
- Ex Paz, et al, 1998
- Management of temporal variability
- Ex Gossym-Comax
11Why 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
12Yield 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
14McGarvey Field Soybean Calibration
15Yield Potential for 1997
Maximum potential yield
Actual Yield
Difference Water Stress, SCN, weeds
16Turn Water Stress Off
Maximum potential yield
Actual yield
Water StressEffect
17Turn SCN Off
Maximum potential yield
Actual yield
SCN Effect
18Turn Weed Effect Off
Maximum potential yield
Actual yield
Weed Effect
19Estimated 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)
20Gossym-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
21Cotton Growth Models
- GOSSYM
- CPM
- Cotton2K
- COTONS