Agricultural Land Rating Systems...

for the Non-Soil Scientist

Earl Yamamoto, State Department of AgricultureFebruary 5, 2000 Advance slide

• Presentation Overview of major rating

systems Comparison of systems What approach?

OVERVIEW

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• Four major systems Land Capability

Classification,USDA

Overall Productivity Rating,Land Study Bureau, UH

Agricultural Lands of Importance to the State of Hawaii (ALISH), DOA/USDA/CTAHR

Land Evaluation & Site Assessment (LESA) System, LESA Commission

OVERVIEW

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Land Capability Classification

USDA1972

• Description Statewide USDA & UH soil

surveys• Soil data used by all systems

Agricultural suitability as limited by soil & climatic conditions• System favors mainland field

crop & mechanization

8 Classes I-VIII, best to worse• Effective cutoff=LCC Class IV

Productivity estimated only for limited crops• Sugar, pine, pasture,

woodland

Soils mapped statewideAdvance slide

Land Capability Classification

USDA1972

• Acreage in Agricultural District LCC I, II & III statewide:

381,609 acres (estimate)

Percent LCC I, II & III:

20.6% of ag district

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Overall Productivity Ratings,Detailed Land Classification

LSB, UH1965-1972

• Description Developed concurrent

with USDA soil survey Soils grouped into land

types based on soil & productive capabilities

Two sets of productivity ratings:• Overall Productivity Rating-

“A”, very good to “E”, not suitable

• Crop Productivity ratings forPine, sugar, vegetables, forage, grazing, orchard, timber

Soil types drawn over aerial photos (variable scales)

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Overall Productivity Ratings,Detailed Land Classification

LSB, UH1965-1972

• Acreage in Agricultural District LSB A-C statewide:

447,250 acres (estimate)

Percent LSB A-C:

24% of ag district

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ALISH

DOA/USDA, UH/CTAHR 1977-78

• Description Part of national effort

(USDA) to inventory important farmlands

National criteria applied, adapted by USDA, CTAHR & DOA

Adopted by State Board of Agriculture, 1977

Broad range of factors considered• Soils, climate, moisture supply,

input use, etc.,• Production-related factors

generalized

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ALISH

DOA/USDA, UH/CTAHR 1977-78

• Description 3 classes of

important agricultural lands• Prime

– Soils with best physical, chemical, & climatic properties for mechanized field crops

– Excludes built-up land/urban, water bodies

• Unique– Land other than prime for

unique high-value crops--coffee, taro, watercress, etc.

• Other important agricultural lands

– State or local important lands for production, not prime or unique; needing irrigation or requiring commercial production management

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ALISH

DOA/USDA, UH/CTAHR 1977-78

• Acreage in Agricultural District ALISH statewide:

846,363 acres (estimate)

Percent ALISH:

45.8% of ag district

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LESA

LESA Commission1983-86

• Description 1983 State Land

Evaluation & Site Assessment Commission(Act 273, Session Laws, 1983)• Standards & criteria for

identifying important agricultural lands

• Inventory of important agricultural land

LESA system• Numeric scoring system• USDA system to determine

impact of federal activity on farmland

• Used to identify lands or evaluate individual sites

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• Description Three components

• Agricultural production goals

• Land evaluation (LE)– Soils, topography, climate

• Site assessment (SA) – Non-physical properties

(location, land use)

LESA

LESA Commission1983-86

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• Description Ag production goals

for crop acreage requirements• Amount of land required to

attain ag production objectives

• Estimates based on current & expected levels of production, population & per capita consumption

• Typical crops profiled:– Sugar, pine, mac nuts, coffee,

local dairy, eggs/poultry

• Crop acreage used to set cutoff score for LESA IAL lands

LESA

LESA Commission1983-86

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• Description Land Evaluation (LE)

• Combines 5 soil ratings into single score for land capability

– LCC– ALISH– LSB– Modified Storie Index– Soil Potential Index

• LE score is weighted average

LESA

LESA Commission1983-86

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• Description Site Assessment (SA)

• Based on USDA LESA manual, selected locational, environmental, operational factors

• 10 site factors;categories of factors:

– Farm productivity/profitability– Land use potential/conflicting uses– Conformance with government

programs/policies

• Soils rated for each criterion, weighted, summed

Final LESA rating=(LE rating+SA score) divided by 2

Threshold score for LESA IAL based on projected acreage

Mapping & GIS coverage limited

LESA

LESA Commission1983-86

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LESA

LESA Commission1983-86

• Acreage in Agricultural District LESA IAL statewide:

759,534 acres (estimate)

Percent LESA IAL:

41.1% of ag district

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Comparison of Systems

• Common features Soils-based with factors

for topography, climate• Vary in consideration of

other attributes like crop yield

Limitations to agricultural productivity considered in some form• Mostly physical and climatic

limitations

All are available on State GIS in some form

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Comparison of Systems

• Major differences Soils-based systems

exclude other factors related to ag profitability

Determination of ag land requirements• LESA system unique in its use

of agricultural production goals

• Other systems do not predetermine land requirements

Incorporation of land use policy considerations• LESA includes policy criteria• Land use policy dealt with in

other systems only by the exclusion of urbanized, built-up, subdivided land

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• Amount of land rated suitable for agriculture

LEAST

LCC 21% of ag district LSB 24%

LESA 41% ALISH 46%

MOST

Comparisonof Systems

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• Comparison of systems

LSB -- “A”-“C” lands

LCC -- Lands better than Class IV

LCC

LESA

LSB

ALISH

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ALISH “Prime” & “Other Important Ag”

LESA Lands above threshold IAL score

Comparison of Systems

• Evaluation criteria (based on CTAHR, 1990) Ease of use

• Low cost, clear explanations, factors well-defined

Objectivity• Measurable factors with

quantifiable data

Consistency• Scores would be same across

individuals, clear definitions, interpretations consistent, no incentive for score manipulation

Adaptability• Can be readily updated to

reflect change

GIS-readinessAdvance slide

Comparison of Systems

• Ease of Use Easiest

•LCCStraightforward use of soils data

•ALISH•LSB

Crop indices & inputs would need to be reassessed; more cost to State

Difficult• LESA

Most complex, scoring system is opaque, mapping problems; most costly to define & use

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Comparison of Systems

• Objectivity Most objective

•LCC•LSB

Criteria clear/quantifiable for both

Less objective•ALISH

No standardized way to define “unique”

Least•LESA

Factors not clear, difficult to quantify & map

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• Consistency Most consistent

•LCC•LSB

Properties, criteria clear

Less so•ALISH

Both “unique” & “other” introduce variability

Least•LESA

Variability in interpreting, assigning values/weights to factors

Comparison of Systems

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• Adaptability Most adaptable

•ALISH Criteria can be reapplied, accommodates unique crops

Less so•LCC

Criteria constant, least sensitive to local crop potential

•LSBDated, system indexed to sugar & pine & farm practices at time

Least•LESA

Components outdated; indexed to sugar & pine; productivity goals rigid; most difficult to update

Comparison of Systems

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• GIS-readiness Most GIS-ready

•LCCUSDA NRCS maintains GIS soils data, source of State GIS data

•ALISHOn State GIS, USDA soils data for update available

Less so•LSB

On State GIS, data old

Least GIS-ready•LESA

Data on State GIS of questionable value/need to redigitize; problems encountered in mapping factors

Comparison of Systems

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Closing Thoughts

• Summary1.Each of the systems has

limitations in application--none ideal2.Ratings change with change in conditions or opportunities

Some examples...

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Closing Thoughts

Example of how one factor--irrigation--changes ratings

Under LCC system, good ag lands WITHOUT irrigation

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Closing Thoughts

... good ag lands WITH irrigation

... without irrigation

Example of how one factor--irrigation--changes ratings

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LSB

“C”“D”

ALISH

“Unique”

Closing Thoughts

Two views of Lanai pineapple under different rating systems--LSB “D” vs. ALISH “Unique”

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Closing Thoughts

LSB

Two views of Hanalei Valley taro under different rating systems--LSB “E” vs. ALISH “Unique”

ALISH “unique”

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Closing Thoughts

3.All need to be updated to reflect present conditions--some more than others

4.In general, system is more robust if:• Emphasis is on resource

suitability• System criteria are well-

defined

• Summary1.Each of the systems has

limitations in application--none ideal

2.Ratings change with change in conditions or opportunities

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Closing Thoughts

• In considering a system... Purpose of ratings:

identify resource,system will be soils-based

Factors of land use policy more appropriate for public decision making process,creates problems if built into rating system

Must weigh value of additional time/money spent on development & maintenance of system

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Credits

Department of AgricultureJames Nakatani, Director

Earl Yamamoto

State Office of Planning, DBEDTDavid Blane, Director

Ruby EdwardsChris Chung

Dennis Kim, State GIS Program