Species Lists (create drop-down lists)

All Species

Grasses 

  • Annual Grasses
    • Annual Ryegrass
    • Corn
    • Pearlmillet
    • Sorghum
    • Sudangrass

Small Grain Cereals 

  • Barley
  • Oats
  • Rye
  • Triticale
  • Wheat
  • Perennial Grasses
    • Bahiagrass
    • Bermudagrass
    • Big Bluestem
    • Blue Grama
    • Buffalograss
    • Buffelgrass
    • Caucasian Bluestem
    • Dallisgrass
    • Eastern Gamagrass
    • Elephantgrass
    • Indiangrass
    • Kentucky Bluegrass
    • Orchardgrass
    • Perennial Ryegrass
    • Prairiegrass
    • Reed Canarygrass
    • Smooth Bromegrass
    • Switchgrass
    • Tall Fescue
    • Timothy
    • Wheatgrasses
      • Crested
      • Intermediate
      • Tall
      • Western

Legumes

  • Annuals
    • Alyceclover
    • Arrowleaf Clover
    • Berseem Clover
    • Crimson Clover
    • Lespedezas
      • Common
      • Korean
    • Vetches
      • Common
      • Hairy
    • Subterranean Clover
  • Perennials
    • ​​​​​​​Alfalfa
    • Alsike Clover
    • Birdsfoot Trefoil
    • Cicer Milkvetch
    • Crownvetch
    • Perennial Peanut
    • Red Clover
    • Sainfoin
    • Sericea Lespedeza
    • White Clover

Forbs

  • Annuals
    • Fodder Beet
    • Kale
    • Rape
    • Turnip
    • Perennials
      • ​​​​​​​Chicory
      • ​​​​​​​Plantain

 

​​​​​​​​​​​​​​​​​​​​​Scope (choice of Alaska, Hawaii, Oregon, or conterminous United States)

 

Factor List (drop-down list of the following)
  • Tmin
  • Tmax
  • Combined Temperature
  • Annual Precipitation
  • Combined Climate Factors
  • Soil pH
  • Soil Drainage
  • Soil Salinity
  • Combined Soil Factors
  • Combined Climate and Soil Factors

Species Suitability Maps

Grass

Suitability Maps

GIS-based suitability zones were divided into four suitability zones, based on their climatic and soil tolerances. An arbitrary classification system based on 25% differences in relative yield (RY) was used:

Classification Relative Yield (RY) %
Unsuited 0-25
Marginally unsuited 26-50
Marginally suited 51-74
Well suited 75-100

Nine maps were created for winter barley, one for each of 3 climate factors and one for each of the soil factors, one combined climate factors map, one combine soil factors map, and a map for all of the factors combined.  This allows for each factor to be examined and addressed to improve suitability through management. Small images of maps are provided below, with larger maps linked by clicking.

 

QUANTITATIVE TOLERANCES GIS-BASED MAPS

The contiguous USA
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

All Climate and Soil Factors (most limiting)

Maximum Temperature

Drainage

All Soil Factors (most limiting)

Precipitation

Salinity

All Climate Factors (most limiting)

 

 

Oat

Based on literature and expert oat specialist counsel, climatic and soil tolerances were compiled. Nine maps were created for oat, one for each of 3 climate factors and one for each of the soil factors, one combined climate factors map, one combined soil factors map, and a map for all of the factors combined.  This allows for each factor to be examined and addressed to improve suitability through management. Small images of maps are provided below, with larger maps linked by clicking. For spring oat, all factors except for Tmin values would be the same.

Climate Factors:
, , ,
Soil Factors:
, ,

To create highly detailed and accurate species suitability maps it was necessary to change from a qualitative description of plant characteristics to an approach that defines tolerances quantitatively. Tolerances to climatic and soil factors were defined (Table 1) and used to map suitability based on summary publications (Moser et al., 1996) and expert knowledge of forage scientists. 

Moser, L.E, D.R. Buxton, and M.D. Casler, Eds. 1996. Cool Season Forage Grasses. American Society of Agronomy Monograph 34. 841 pp. ASA, CSSA, and SSSA, Madison, WI. 

Suitability patterns for forage species are caused by different factors in different locations. Low winter temperatures limit the northern range of many species, while low precipitation limits the western range of species in the semi-arid west. Low summer temperatures limit the range of species with increasing elevation while high summer temperatures limit the range in the desert southwest and hot and humid southeast. Soil characteristics (pH, drainage, and salinity) also limit the suitability zones of forage species. However, soil amendments (liming and drainage tiles) can alleviate many of these limitations.  Thus, NRCS Soil Survey data should be informed and revised by management mitigations. 

GIS software allow creation of highly detailed and accurate species suitability mapping based on biophysical characteristics of the region and plant characteristics (Hannaway et al., 2005). Precipitation and maximum and minimum temperature climate grids are now available for annual and  monthly periods. Soil type, depth, drainage, pH, salinity, and alkalinity information was obtained from the NRCS STATSGO2 database. Species characteristics were provided by forage experts.

Hannaway, D.B., C. Daly, L. Coop, D. Chapman, and Y. Wei. 2005. GIS-based Forage Species Adaptation Mapping. pp. 319-342. In: S.G. Reynolds and J. Frame (eds). Grasslands: Developments, Opportunities and Perspectives. FAO and Science Pub. Inc., Rome, Italy.

 

Maps

Nine maps were developed; 1) 30-year long-term July maximum temperature 2) 30-year long-term January minimum temperature, 3) 30-year long-term annual precipitation, 4) soil pH, 5) soil drainage, 6) soil salinity, 7) combined climate factors, 8) combined soil factors, and 9) combined climate and soil factors.

Climate: Tmax, Tmin, Ppt, Combined

 

Soil: pH, Drainage, Salinity, Combined

 

All Factors

 

 

Climate Factors:
, , ,
Soil Factors:
, ,

To create highly detailed and accurate species suitability maps it was necessary to change from a qualitative description of plant characteristics to an approach that defines tolerances quantitatively. Tolerances to climatic and soil factors were defined (Table 1) and used to map suitability based on summary publications (Moser et al., 1996) and expert knowledge of forage scientists. 

Moser, L.E, D.R. Buxton, and M.D. Casler, Eds. 1996. Cool Season Forage Grasses. American Society of Agronomy Monograph 34. 841 pp. ASA, CSSA, and SSSA, Madison, WI. 

Suitability patterns for forage species are caused by different factors in different locations. Low winter temperatures limit the northern range of many species, while low precipitation limits the western range of species in the semi-arid west. Low summer temperatures limit the range of species with increasing elevation while high summer temperatures limit the range in the desert southwest and hot and humid southeast. Soil characteristics (pH, drainage, and salinity) also limit the suitability zones of forage species. However, soil amendments (liming and drainage tiles) can alleviate many of these limitations.  Thus, NRCS Soil Survey data should be informed and revised by management mitigations. 

GIS software allow creation of highly detailed and accurate species suitability mapping based on biophysical characteristics of the region and plant characteristics (Hannaway et al., 2005). Precipitation and maximum and minimum temperature climate grids are now available for annual and  monthly periods. Soil type, depth, drainage, pH, salinity, and alkalinity information was obtained from the NRCS STATSGO2 database. Species characteristics were provided by forage experts.

Hannaway, D.B., C. Daly, L. Coop, D. Chapman, and Y. Wei. 2005. GIS-based Forage Species Adaptation Mapping. pp. 319-342. In: S.G. Reynolds and J. Frame (eds). Grasslands: Developments, Opportunities and Perspectives. FAO and Science Pub. Inc., Rome, Italy.

Maps

Nine maps were developed; 1) 30-year long-term July maximum temperature 2) 30-year long-term January minimum temperature, 3) 30-year long-term annual precipitation, 4) soil pH, 5) soil drainage, 6) soil salinity, 7) combined climate factors, 8) combined soil factors, and 9) combined climate and soil factors.

Climate: Tmax, Tmin, Ppt, Combined

Soil: pH, Drainage, Salinity, Combined

All Factors

Climate Factors:
, , ,
Soil Factors:
, ,
Rye

Global and USA Suitability

The United States is a significant producer of rye. In 2020 the U.S. produced roughly 11.5 million bushels of rye that was valued at approximately $59.8 million. The marketing year average price for rye was $5.20 per bushel. In 2022, 12.3 million bushels of rye were produced, an increase of about 9.8 million bushels from the 2021 total production. The national average yield for rye is around 35 bu per acre.

Winter rye is commonly planted as a cover crop. As an example, in 2021, of the 2.1 million acres planted only 294,000 acres were harvested for grain. Therefore, a significant market for rye can be for seed that will be planted as a cover crop. The states with the most harvested acres of rye are Oklahoma, North Dakota, Minnesota, Pennsylvania, and Wisconsin.

Suitability Zones

GIS-based suitability zones were divided into four suitability zones, based on their climatic and edaphic tolerances. An arbitrary classification system based on 25% differences in relative yield (RY) was used: (1) 75-100% RY = well-suited; (2) 50-75% RY = moderately-suited; (3) 25-50% RY = marginally-suited; and (4) 0-25% RY = not suited.

 

 

Climate Factors:
, , ,
Soil Factors:
, ,
Climate Factors:
, , ,
Soil Factors:
, ,

Based on literature and expert triticale specialist counsel, climatic and soil tolerances were compiled. Nine maps were created for winter triticale, one for each of 3 climate factors and one for each of the soil factors, one combined climate factors map, one combine soil factors map, and a map for all of the factors combined.  This allows for each factor to be examined and addressed to improve suitability through management. Small images of maps are provided below, with larger maps linked by clicking. For spring barley, all factors except for Tmin values would be the same.

Climate Factors:
, , ,
Soil Factors:
, ,

Based on literature and expert wheat specialist counsel, climatic and soil tolerances were compiled. Nine maps were created for winter wheat, one for each of 3 climate factors and one for each of the soil factors, one combined climate factors map, one combined soil factors map, and a map for all of the factors combined.  This allows for each factor to be examined and addressed to improve suitability through management. Small images of maps are provided below, with larger maps linked by clicking. For spring wheat, all factors except for Tmin values would be the same.

 

Climate Factors:
, , ,
Soil Factors:
, ,

Legume

Defining the regions within the USA where the various fall dormancy (FD) and winter survival index (WSI) alfalfa cultivar types can be successfully used is an important marketing and management application of GIS technologies. These maps provide a guide for cultivar selection decisions and for identifying areas for conducting further field evaluations to validate and/or revise these maps.

Low winter temperatures limit the northern range of the FD and WSI types, while other climate and soil factors also combine to define optimal cultivar characteristics.

Agronomic field trials have been the standard evaluation technique for selecting cultivars, but extrapolation of information from one site to another for these types of trials has always been problematic. By developing suitability zone maps, based on our best knowledge of cultivar characteristics, field-based evaluation can make more efficient use of available testing resources. Using these techniques and technologies, the limited number of field trials can be extended across the USA and contribute to the global suitability information contained in the quantitative tolerances tables and function.

 Drop-down menu for Fall Dormancy Level

 

Drop-down menu for Winter Survival Index

 

Climate

  Jan Tmin

  Jul Tmax

  Ann Precipitation

  Combined

Soil

  pH

  Drainage

  Salinity

  Combined

Climate and Soil Combined

Historically, maps have been drawn based on primary use areas, showing broad geographic areas, e.g. Compendium of Common Forages maps within Forages: An Introduction to Grassland Agriculture, 7th ed. (2018), John Wiley & Sons, Inc.

(Alsike clover generalized adaptation and common use map.)

More highly detailed maps, based on quantitative climatic and soil factor tolerances and using GIS spatial grids, provide information on where species are suitable for a variety of intended uses.

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database. The procedure used to produce these suitability maps is described below.

Suitability curves were developed for each clover species for three climate variables (average annual precipitation, average July maximum temperature, and average annual extreme low temperature) and three soil variables (drainage class, pH, and salinity). For each variable and each species, the curves were fit using estimated yield data across the full range of values for the given variable.  

The coefficients for the model equations were applied to spatial data layers representing each climate and soil variable, resulting in spatial outputs of percent yield for each of the clover species and each climate and soil variable. The percent yield layers were then classified into four suitability classes, as follows: 

100%-75% - Suitable
75%-50%  - Moderately suitable
50%-25%  - Marginally suitable
25-0%    - Not suitable

Finally, three "hybrid" suitability layers were produced for each clover species based on combinations of 1) the three climate variables, 2) the three soil variables, and 3) all six climate and soil variables together.  These combined suitability layers were created by selecting for each location the lowest suitability value of the included variables, with the idea that the overall suitability for a species will be limited by the most restrictive factor. 

Data sources
----------------
Climate data: 800m PRISM 30-year normals for years 1981-2010 (PRISM Climate Group, Oregon State University, http://prism.oregonstate.edu, accessed 2018-01-17)

Soils data:  NRCS STATSGO (Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. U.S. General Soil Map (STATSGO2). Available online at https://sdmdataaccess.sc.egov.usda.gov. Accessed 2018-01-10)

 

Quantitative Tolerances GIS-based Maps

The contiguous USA

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

Click on the thumbnail image to view a larger map.

 
State Maps
Alaska
Climate Factors Soil Factors Combined Factors

Minimum temperature

pH

Climate and Soil

Maximum temperature

Drainage

All Climate

Precipitation

Salinity

All Soil

Hawaii
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Climate

Precipitation

Salinity

All Soil

Oregon
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Climate

Precipitation

Salinity

All Soil

Historically, maps have been drawn based on primary use areas, showing broad geographic areas, e.g. Compendium of Common Forages maps within Forages: An Introduction to Grassland Agriculture, 7th ed. (2018), John Wiley & Sons, Inc.

 

More highly detailed maps, based on quantitative climatic and soil factor tolerances and using GIS spatial grids, provide information on where species are suitable for a variety of intended uses.

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database. The procedure used to produce these suitability maps is described below.

Suitability curves were developed for each clover species for three climate variables (average annual precipitation, average July maximum temperature, and average annual extreme low temperature) and three soil variables (drainage class, pH, and salinity). For each variable and each species, the curves were fit using estimated yield data across the full range of values for the given variable.  

The coefficients for the model equations were applied to spatial data layers representing each climate and soil variable, resulting in spatial outputs of percent yield for each of the clover species and each climate and soil variable. The percent yield layers were then classified into four suitability classes, as follows: 

Classification Relative Yield (RY) %
Unsuited 0-25
Marginally unsuited 26-50
Marginally suited 51-74
Well suited 75-100

 

Finally, three "hybrid" suitability layers were produced for each clover species based on combinations of 1) the three climate variables, 2) the three soil variables, and 3) all six climate and soil variables together.  These combined suitability layers were created by selecting for each location the lowest suitability value of the included variables, with the idea that the overall suitability for a species will be limited by the most restrictive factor. 

Data sources
----------------
Climate data: 800m PRISM 30-year normals for years 1981-2010 (PRISM Climate Group, Oregon State University, http://prism.oregonstate.edu, accessed 2018-01-17)

Soils data:  NRCS STATSGO (Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. U.S. General Soil Map (STATSGO2). Available online at https://sdmdataaccess.sc.egov.usda.gov. Accessed 2018-01-10.

 

QUANTITATIVE TOLERANCES GIS-BASED MAPS

The contiguous USA

Climate Factors

Soil Factors

Combined Factors

Minimum Temperature

pH

All climate and soil factors (most limiting)

Maximum Temperature

Drainage

All soil factors (most limiting)

Precipitation

Salinity

All climate factors (Most limiting)

Click on the thumbnail image to view a larger map.

 
State Maps
Alaska
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Climate

Precipitation

Salinity

All Soil

 

Hawaii

 

Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Climate

Precipitation

Salinity

All Soil

Oregon
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Climate

Precipitation

Salinity

All Soil

 

Historically, maps have been drawn based on primary use areas, showing broad geographic areas, e.g. Compendium of Common Forages maps within Forages: An Introduction to Grassland Agriculture, 7th ed. (2018), John Wiley & Sons, Inc.

 

 

More highly detailed maps, based on quantitative climatic and soil factor tolerances and using GIS spatial grids, provide information on where species are suitable for a variety of intended uses.

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database.

 Suitability curves were developed for each clover species for three climate variables (average annual precipitation, average July maximum temperature, and average annual extreme low temperature) and three soil variables (drainage class, pH, and salinity). For each variable and each species, the curves were fit using estimated yield data across the full range of values for the given variable.  

The coefficients for the model equations were applied to spatial data layers representing each climate and soil variable, resulting in spatial outputs of percent yield for each of the clover species and each climate and soil variable. The percent yield layers were then classified into four suitability classes, as follows: 

100%-75% - Suitable
75%-50%  - Moderately suitable
50%-25%  - Marginally suitable
25-0%    - Not suitable

Finally, three "hybrid" suitability layers were produced for each clover species based on combinations of 1) the three climate variables, 2) the three soil variables, and 3) all six climate and soil variables together.  These combined suitability layers were created by selecting for each location the lowest suitability value of the included variables, with the idea that the overall suitability for a species will be limited by the most restrictive factor. 

 QUANTITATIVE TOLERANCES GIS-BASED MAPS

The contiguous USA

Climate Factors

Soil Factors

Combined Factors

Minimum Temperature


pH

 

All climate and soil factors (most limiting)

 

 

Maximum Temperature

Drainage

All soil factors (most limiting)

 

Precipitation

Salinity

All climate factors (Most limiting)

Berseem clover primary use areas as a summer or winter annual.

Source: Clark, Andy (ed.). 2007. Berseem Clover. In: Managing Cover Crops Profitably, 3rd ed. Sustainable Agriculture Network, Beltsville, MD.

Climate Factors:
, ,
Soil Factors:
, ,

Historically, maps have been drawn based on primary use areas, showing broad geographic areas, e.g. Compendium of Common Forages maps within Forages: An Introduction to Grassland Agriculture, 7th ed. (2018), John Wiley & Sons, Inc.

(Crimson clover adaptation and use map.)

Crimson Clover SARE Cover Crop Map

 

(Crimson clover SARE cover crop map. Source: Managing Cover Crops Profitably, 3rd Ed., Sustainable Agriculture Research & Education.)

 

More highly detailed maps, based on quantitative climatic and soil factor tolerances and using GIS spatial grids, provide information on where species are suitable for a variety of intended uses.

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database.

 

Quantitative Tolerances GIS-based Maps

The contiguous USA
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

 

State Maps
Alaska

Climate Factor

Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

Hawaii

Climate Factor

Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

 

Oregon

Climate Factor

Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

Historically, maps have been drawn based on primary use areas, showing broad geographic areas, e.g. Compendium of Common Forages maps within Forages: An Introduction to Grassland Agriculture, 7th ed. (2018), John Wiley & Sons, Inc.

(Kura clover adaptation and use map.)

More highly detailed maps, based on quantitative climatic and soil factor tolerances and using GIS spatial grids, provide information on where species are suitable for a variety of intended uses.

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database.

 

Quantitative Tolerances GIS-based Maps

The contiguous USA
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

 
State Maps
Alaska
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

 
Hawaii
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

 

Oregon
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database. The procedure used to produce these suitability maps is described below.

Suitability curves were developed for each clover species for three climate variables (average annual precipitation, average July maximum temperature, and average annual extreme low temperature) and three soil variables (drainage class, pH, and salinity). For each variable and each species, the curves were fit using estimated yield data across the full range of values for the given variable.  

The coefficients for the model equations were applied to spatial data layers representing each climate and soil variable, resulting in spatial outputs of percent yield for each of the clover species and each climate and soil variable. The percent yield layers were then classified into four suitability classes, as follows: 

100%-75% - Suitable
75%-50%  - Moderately suitable
50%-25%  - Marginally suitable
25-0%    - Not suitable

Finally, three "hybrid" suitability layers were produced for each clover species based on combinations of 1) the three climate variables, 2) the three soil variables, and 3) all six climate and soil variables together.  These combined suitability layers were created by selecting for each location the lowest suitability value of the included variables, with the idea that the overall suitability for a species will be limited by the most restrictive factor. 

QUANTITATIVE TOLERANCES GIS-BASED MAPS

The contiguous USA

Climate Factors

Soil Factors

Combined Factors

Minimum Temperature

pH

All climate and soil factors (most limiting)

 

 

Maximum Temperature

Drainage

All soil factors (most limiting)

 

Precipitation

Salinity

All climate factors (Most limiting)

Historically, maps have been drawn based on primary use areas, showing broad geographic areas, e.g. Compendium of Common Forages maps within Forages: An Introduction to Grassland Agriculture, 7th ed. (2018), John Wiley & Sons, Inc.

(Red clover adaptation and use map.)

More highly detailed maps, based on quantitative climatic and soil factor tolerances and using GIS spatial grids, provide information on where species are suitable for a variety of intended uses.

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database.

 

Quantitative Tolerances GIS-based Maps

The contiguous USA
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

 
State Maps
Alaska
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

Hawaii
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

 

Oregon
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database. The procedure used to produce these suitability maps is described below.

Suitability curves were developed for each clover species for three climate variables (average annual precipitation, average July maximum temperature, and average annual extreme low temperature) and three soil variables (drainage class, pH, and salinity). For each variable and each species, the curves were fit using estimated yield data across the full range of values for the given variable.  

The coefficients for the model equations were applied to spatial data layers representing each climate and soil variable, resulting in spatial outputs of percent yield for each of the clover species and each climate and soil variable. The percent yield layers were then classified into four suitability classes, as follows: 

100%-75% - Suitable
75%-50%  - Moderately suitable
50%-25%  - Marginally suitable
25-0%    - Not suitable

Finally, three "hybrid" suitability layers were produced for each clover species based on combinations of 1) the three climate variables, 2) the three soil variables, and 3) all six climate and soil variables together.  These combined suitability layers were created by selecting for each location the lowest suitability value of the included variables, with the idea that the overall suitability for a species will be limited by the most restrictive factor. 

QUANTITATIVE TOLERANCES GIS-BASED MAPS

The contiguous USA

Climate Factors

Soil Factors

Combined Factors

Minimum Temperature

pH

All climate and soil factors (most limiting)

 

 

Maximum Temperature

Drainage

All soil factors (most limiting)

 

Precipitation

Salinity

All climate factors (Most limiting)

Historically, maps have been drawn based on primary use areas, showing broad geographic areas, e.g. Compendium of Common Forages maps within Forages: An Introduction to Grassland Agriculture, 7th ed. (2018), John Wiley & Sons, Inc.

 

More highly detailed maps, based on quantitative climatic and soil factor tolerances and using GIS spatial grids, provide information on where species are suitable for a variety of intended uses.

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database.

 

GIS-based quantitative tolerances maps

The contiguous USA
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

 

State Maps
Alaska

Climate Factor

Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

Hawaii

Climate Factor

Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate


Oregon

Climate Factor

Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

Historically, maps have been drawn based on primary use areas, showing broad geographic areas, e.g. Compendium of Common Forages maps within Forages: An Introduction to Grassland Agriculture, 7th ed. (2018), John Wiley & Sons, Inc.

(Subterranean Clover Adaptation & Use Map.)

(SARE Managing Cover Crops Map. Source: Managing Cover Crops Profitably, 3rd Ed., Sustainable Agriculture Research & Education.)

More highly detailed maps, based on quantitative climatic and soil factor tolerances and using GIS spatial grids, provide information on where species are suitable for a variety of intended uses.

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database.

 

Quantitative Tolerances GIS Maps

The contiguous USA
Climate Factors Soil Factors Combined Factors

Minimum Temperature Wet

pH Wet

Climate and Soil Wet

Minimum Temperature Dry

pH Dry

Climate and Soil Dry

Maximum Temperature Wet

Drainage Wet

All Soil

Precipitation Wet

Salinity Wet

All Climate Wet

Precipitation Dry

Salinity Dry

All Climate Dry

Map designations of wet and dry refer to different precipitation requirements for current use areas (40-60 inch rainfall zones, designated wet) and potential use areas (16-26 inch rainfall zones, designated dry). 

 

State Maps
Alaska
Climate Factors Soil Factors Combined Factors

Minimum Temperature Wet

pH Wet

Climate and Soil Wet

Minimum Temperature Dry

pH Dry

Climate and Soil Dry

Maximum Temperature Wet

Drainage Wet

All Soil Wet

Precipitation Wet

Salinity Wet

All Climate Wet

Precipitation Dry

Salinity Dry

All Climate Dry

Hawaii
Climate Factors Soil Factors Combined Factors

Minimum Temperature Wet

pH Wet

Climate and Soil Wet

Minimum Temperature Dry

 

pH Dry

Climate and Soil Dry

Maximum Temperature Wet

Drainage Wet

All Soil Wet

 

Precipitation Wet

 

Salinity Wet

All Climate Wet

Precipitation Dry

 

Salinity Dry

All Climate Dry

 

Oregon
Climate Factors Soil Factors Combined Factors

Minimum Temperature Wet

pH Wet

Climate and Soil Wet

 

Minimum Temperature Dry

pH Dry

Climate and Soil Dry

Maximum Temperature Wet

Drainage Wet

All Soil Wet

Precipitation Wet

Salinity Wet

All Climate Wet

Precipitation Dry

Salinity Dry

All Climate Dry

Historically, maps have been drawn based on primary use areas, showing broad geographic areas, e.g. Compendium of Common Forages maps within Forages: An Introduction to Grassland Agriculture, 7th ed. (2018), John Wiley & Sons, Inc.


(White clover adaptation an use map.)

More highly detailed maps, based on quantitative climatic and soil factor tolerances and using GIS spatial grids, provide information on where species are suitable for a variety of intended uses.

The following collection of maps were developed by a group of Oregon State University scientists, using the PRISM-generated collection of climate factor grids and the NRCS soil characteristics database.

 

GIS-based Quantitative Tolerances Maps

The contiguous U.S.
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

 

State Maps
Alaska
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate

Hawaii
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

 

Precipitation

Salinity

All Climate

Oregon
Climate Factors Soil Factors Combined Factors

Minimum Temperature

pH

Climate and Soil

Maximum Temperature

Drainage

All Soil

Precipitation

Salinity

All Climate