Drainage, extracted from STATSGO
or SSURGO soil data, was a categorical rating with eight categories from excessively drained to very poorly drained and water.
GEI, genotype by environment interactions: GGE, genotype main effects plus genotype by environment interaction effects; GIS, geographic information system; MET, multienvironment trials; NOAA, National Oceanic and Atmospheric Administration; RCB, randomized complete block design; STATSGO
, state soil geographic database; TPE, target population of environments.
Soil texture classifications of samples from the sites were compared with those listed in STATSGO
, the soils database (STATSGO
, Washington, DC), and Spearman rank correlation was used to assess correlations between field data and data from the GIS.
To assess soil drainage, the STATSGO
database was analyzed by individual Hydrologic Soil Groups by map unit in the database.
databases aggregate county soil survey maps to represent soil patterns at the scale of a state or region (1:250 000) (USDA 1991).
map is linked to the USDA's Soil Interpretations Record (SIR) attribute database, which gives the proportionate extent of the component soils and their properties for each map unit.
Soil properties at the three locations were obtained from the USDA NRCS SSURGO and STATSGO
databases (Soil Survey Staff 2007) included with the EPIC model (table 1).
databases divide states into polygons of similar aggregate soil characteristics called Soil Associations (SA).
In locations where SSURGO is not available, the tabular data can be still obtained from the STATSGO
database (USDA, 1994), but maps must be created by other means.
Curve number II was assigned based on the dominant land use from National Land Cover Dataset and soil hydrologic group from STATSGO
according to the Soil Conservation Service's (SCS) Texas Engineering Technical Note No.
One of these data sets is part of the STATSGO
(State Soil Geographic) database (USDA, 1994) at the 1:250,000 scale underlying map.
For soil inputs, the STATSGO
database was used to extract data layers for sand, clay and organic matter contents, using the same approach used earlier to extract the values of K.