Department of Pesticide Regulation 

Mary-Ann Warmerdam 

Director M E M O R A N D U M Arnold Schwarzenegger 

Governor 

1001 I Street • P.O. Box 4015 • Sacramento, California 95812-4015 • www.cdpr.ca.gov

A Department of the California Environmental Protection Agency 

 Printed on recycled paper, 100% post-consumer--processed chlorine-free. 

TO: Randy Segawa 

 Environmental Program Manager I 

 Environmental Monitoring Branch 

FROM: Bruce Johnson, Ph.D. Original signed by

 Research Scientist III 

 Environmental Monitoring Branch 

 916-324-4106 

 Frank C. Spurlock, Ph.D. Original signed by

 Research Scientist III 

 Environmental Monitoring Branch 

DATE: January 23, 2009 

SUBJECT: DOMINANT SOIL TYPES ASSOCIATED WITH FUMIGANT APPLICATIONS 

IN OZONE NONATTAINMENT AREAS 

Background

The Environmental Monitoring Branch is investigating the ability of computer simulation 

models to describe post-application fumigant fluxes. The primary objective is to simulate total 

cumulative volatilization for different application methods and fumigants for use in the volatile 

organic compound (VOC) program. The purpose of this memorandum is to document a 

procedure for determining the dominant soil types associated with fumigant use in different 

regions of California. 

Methods 

Database operations were performed using Oracle and SAS. Fumigant use records consisting 

of pounds of fumigant active ingredient (A.I.), and acres treated, county, meridian, township, 

range, and section were extracted from the 2006 pesticide use report (PUR). Data for 

1,3-dichloropropene (1,3-d), methyl bromide, chloropicrin, metam sodium, and metam potassium 

were included, and only records for use during the May 1 through October 31, 2006 ozone season 

were included. Applications were also restricted to nonattainment areas (NAAs) as defined by a 

lookup table of county, meridian, township, range, section (COMTRS) in each NAA created for the 

VOC calculation program. The five NAAs are Sacramento Valley (Sacvalley), San Joaquin 

Valley (SJV), Southeast Desert (SE_desert), South Coast (SoCoast), and Ventura. For each 

COMTRS, the sum of pounds applied and acres treated were determined. 

In parallel, the following surface soil information was extracted from an existing Oracle table 

(Troiano.layer99): soil texture class, textural subclass modifier, area of soil class within the 

COMTRS and COMTRS area. The soils data in Troiano.layer99 were originally obtained from 
Randy Segawa 

January 23, 2009 

Page 2 

Soil Conservation Service county soil surveys (Soil Conservation Service, 1973; Soil Survey 

Staff, 1997). An additional variable named class_frac that describes the fraction of soil type 

within each COMTRS was created by dividing the acreage of each soil type within a section by 

the total COMTRS acreage. These sectional soil factors were then merged with the use 

information by COMTRS, and sections with no fumigant use were discarded. The Appendix 

contains a more detailed set of notes on these operations. 

This resulted in a set of records for each application of each fumigant in each section containing 

COMTRS, soil class, fraction by acreage of this soil class within section, NAA, and both pounds 

of fumigant applied and acres treated during the 2006 ozone season. An application within a 

section would potentially be listed several times, depending on how many soil types were in that 

section. The pounds applied and acres treated were apportioned over the soil types using 

class_frac, the fraction of each soil type within the section. In other words, use within each soil 

type within a section was indexed in two ways: (1) the product of class_frac and pounds applied 

and (2) the product of class_frac and acres treated. An important methodological feature was that 

all soils within a section were listed if there was any fumigant use within the section, regardless of 

whether fumigant use actually occurred on that soil type. The available information does not 

enable locating individual applications on 

specific soil types. Thus, strictly speaking, the 

soil classes determined in this analysis cannot be 

described as those soils upon which these 

fumigants were applied. Rather, these soils 

represent the dominant soils in sections where 

fumigants were used. 

For each fumigant within each NAA, these 

weighted use measures were summed by soil 

class (using Excel pivot table) producing a table 

of NAA x soil type of pounds applied and 

acreage treated. Subsequently we decided that 

pounds applied was the most important index of 

use and acreage was not included in the write up. 

The soil classification scheme in Troiano.layer99 

included modifiers such as fine sandy loam and 

coarse sandy loam. which resulted in 18 classes. 

In addition, a soil class “unknown” was 

assigned to sections which did not have soil 

mapping information. In order to further 

Soil classes with finer 

divisions

Broader soil classes 

(soil textural triangle)

CLAY clay

CLAYLOAM clayloam

COARSESAND sand

COARSESANDYLOAM sandyloam

FINESAND sand

FINESANDYLOAM sandyloam

LOAM loam 

LOAMYCOARSESAND loamysand

LOAMYFINESAND loamysand

LOAMYSAND loamysand

SAND sand

SANDYCLAYLOAM sandyclayloam

SANDYLOAM sandyloam

SILTLOAM siltloam

SILTYCLAY siltyclay

SILTYCLAYLOAM siltyclayloam

UNKNOWN unknown

VERYFINESANDYLOAM sandyloam

Table 1. Soil class mapping from finer division to 

broader divisions. All classes are USDA/SCS soil 

classes.
Randy Segawa 

January 23, 2009 

Page 3 

simplify, these 18 groups were aggregated into 12 soil types, plus unknown (Table 1). These 12 

soil types are those listed in the USDA/SCS soil triangle. 

Results 

The distribution of the five fumigants over the NAAs was highly uneven (Table 2). The SJV 

NAA received the largest total pounds of applied fumigants, consisting of 5,439,391 pounds. The 

next largest was Ventura with about one-fifth of SJV at 1,118,998 pounds. The other three NAAs 

had totals which were smaller than SJV by more than an order of magnitude. Pounds applied in 

SJV and Ventura comprised 94% of the total pounds applied. The largest two fumigants were 

metam sodium and 1,3-d at 3,149,867 and 1,721,848 pounds A.I., respectively. These two 

fumigants accounted for 70% of the pounds of fumigants applied in these five NAAs in the 2006 

VOC season (May to October). 

The fraction of use in each soil type by NAA and fumigant is depicted in Table 3. The first and 

second highest fractions within each NAA are highlighted by orange and light blue, respectively. 

Sandy loam dominates the soil types in the SJV over all five fumigants. Similarly, in Ventura 

sandy loam is the highest fraction, except for metam sodium, where loamy sand is the highest 

and sandy loam is the second highest. Outside of the Sacvalley, four soil classes appear to 

dominate the areas where fumigants are used: loam, loamy sand, sand, and sandy loam. In the 

Sacvalley clay loam, silty clay loam, and silt loam were amongst the top two soil types present in 

sections with fumigant applications. As discussed previously, the spatial resolution of the 

fumigant PUR data is only to the section level. Consequently, Table 3 does not describe the 

extent to which fumigants are actually applied to specific soil types, but rather the use-weighted 

fraction of soil types in sections were fumigants were applied for each NAA. 

Sacvalley SE_desert SJV SoCoast Ventura Total

Methyl Bromide 300 671 399,589 57,258 310,895 768,713

Chloropicrin 2,401 6,213 100,397 74,444 383,645 567,098

Metam Sodium 38,051 163,340 2,805,682 5,379 137,415 3,149,867

1,3-d 40,042 7,825 1,361,078 25,860 287,043 1,721,848

Metam Potassium 7,742 0 772,645 0 0 780,387

Total 88,535 178,049 5,439,391 162,941 1,118,998 6,987,914

Table 2. Pounds of A.I. applied in NAAs from May through October 2006.
Randy Segawa 

January 23, 2009 

Page 4 

The representation of four classes: loam, loamy sand, sandy loam, and sand is explicitly 

presented in Table 4. Generally, fractions exceeded 0.5. It was not possible to classify soils in 

some sections and these application pounds were assigned to the unknown soil class. Soil type 

unknown was prominent in SE_desert for metam sodium, SJV and SoCoast for 1,3-d and SJV 

for metam potassium (Table 3). 

Soil Class Sacvalley SE_desert SJV SoCoast Ventura Soil Class Sacvalley SE_desert SJV SoCoast Ventura

clay 0.00 0.00 0.01 0.01 0.00 clay 0.00 0.00 0.00 0.00 0.03

clayloam 0.30 0.00 0.02 0.04 0.01 clayloam 0.20 0.00 0.02 0.03 0.02

loam 0.08 0.00 0.08 0.87 0.09 loam 0.14 0.00 0.09 0.65 0.26

loamysand 0.21 0.00 0.05 0.00 0.02 loamysand 0.00 0.00 0.06 0.10 0.05

sand 0.00 1.00 0.02 0.00 0.02 sand 0.00 0.46 0.08 0.00 0.02

sandyclayloam 0.00 0.00 0.00 0.00 0.00 sandyclayloam 0.00 0.00 0.00 0.00 0.00

sandyloam 0.39 0.00 0.81 0.06 0.58 sandyloam 0.11 0.47 0.65 0.06 0.52

siltloam 0.02 0.00 0.00 0.00 0.00 siltloam 0.20 0.00 0.00 0.04 0.00

siltyclay 0.00 0.00 0.00 0.00 0.00 siltyclay 0.12 0.00 0.00 0.00 0.00

siltyclayloam 0.00 0.00 0.01 0.00 0.28 siltyclayloam 0.23 0.07 0.01 0.07 0.10

unknown 0.00 0.00 0.02 0.03 0.00 unknown 0.00 0.00 0.09 0.04 0.00

Soil Class Sacvalley SE_desert SJV SoCoast Ventura Soil Class Sacvalley SE_desert SJV SoCoast Ventura

clay 0.02 0.06 0.00 0.00 0.01 clay 0.06 0.00 0.04 0.02 0.00

clayloam 0.05 0.08 0.00 0.00 0.01 clayloam 0.00 0.00 0.06 0.01 0.02

loam 0.33 0.01 0.01 0.02 0.03 loam 0.01 0.00 0.07 0.28 0.08

loamysand 0.00 0.01 0.17 0.04 0.55 loamysand 0.00 0.00 0.09 0.01 0.02

sand 0.00 0.00 0.31 0.02 0.05 sand 0.00 0.82 0.04 0.00 0.02

sandyclayloam 0.00 0.01 0.00 0.00 0.00 sandyclayloam 0.00 0.00 0.00 0.00 0.00

sandyloam 0.09 0.42 0.47 0.69 0.21 sandyloam 0.69 0.15 0.51 0.37 0.61

siltloam 0.24 0.01 0.03 0.00 0.14 siltloam 0.15 0.03 0.00 0.00 0.00

siltyclay 0.00 0.00 0.00 0.00 0.00 siltyclay 0.00 0.00 0.00 0.00 0.00

siltyclayloam 0.27 0.00 0.01 0.23 0.00 siltyclayloam 0.09 0.00 0.01 0.14 0.24

unknown 0.00 0.41 0.00 0.00 0.00 unknown 0.00 0.00 0.17 0.16 0.01

Soil Class Sacvalley SJV

clay 0.21 0.02

clayloam 0.00 0.32

loam 0.01 0.02

loamysand 0.00 0.04

sand 0.00 0.04

sandyloam 0.06 0.40

siltloam 0.33 0.00

siltyclay 0.19 0.01

siltyclayloam 0.20 0.00

unknown 0.00 0.15

Metam Potassium

Table 3. Fumigant use (pounds of active ingredient applied) expressed as normalized weights within each NAA as distributed over basic soil types 

based on 2006 PUR restricted to five NAAs and for applications from May through October. The shaded cells represent the highest and second 

highest soil use weights within each NAA. For example, sandyloam was highest at 0.81 for SJV and loam was second at 0.08.

Methyl Bromide Chloropicrin

Metam Sodium 1,3-dichloropropene
Randy Segawa 

January 23, 2009 

Page 5 

Conclusion

The PUR for 2006 was queried for fumigant use within the five NAAs for 2006. The resulting 

section by section use information was merged with soils information and the dominant soil 

types within sections associated with fumigant use was quantified. Excluding the Sacvalley, four 

dominant soil types occurred in sections with fumigant use: loam, loamy sand, sandy loam, and 

sand. 

Sacvalley SE_desert SJV SoCoast Ventura

Methyl Bromide 0.69 1.00 0.95 0.92 0.72

Chloropicrin 0.25 0.93 0.88 0.81 0.84

Metam Sodium 0.42 0.44 0.96 0.77 0.85

1,3-dichloropropene 0.70 0.97 0.71 0.66 0.72

Metam Potassium 0.07 0.49

Table 4. Summary of fraction of soils in the groups: loam, sandy loam, loamy 

sand and loam.
Randy Segawa 

January 23, 2009 

Page 6 

References 

Soil Conservation Service. 1983. National soils handbook. Soil Conservation Service, 

U.S. Department of Agriculture, U.S. Govt. Print. Off., Washington D.C. 

Soil Survey Staff. 1997. Title 430 National Soil Survey Handbook, Revision Issued 

December, 1997. National Resources Conservation Service, Washington D.C., U.S. 

Government Printing Office, December 1997.
Randy Segawa 

January 23, 2009 

Page 7 

APPENDIX 

PROCEDURE FOR ESTIMATING FRACTIONS OF FUMIGANT APPLICATIONS 

APPLIED TO DIFFERENT SOIL TEXTURES IN NAAs 

1. create 2006 ozone season fumigant use data (lbs applied, acres_treated) listed by comtrs, 

fumigant, and NAA. 

a. source is PUR (see example SQL query)and then imported into SAS. Unit_treated=’A’ 

only; chemicals = chloropicrin, methyl bromide, 1,3-d, metam sodium and metam 

potassium. 

b. screen comtrs to include only sections in each NAA using VOC NAA comtrs lookup 

table, file=new_statewide_AB_NAA.dat 

c. create sum_lbs_applied and sum_acre_treated for each comtrs 

d. dataset created=WORK.FUMI 

2. run “import_all_soildata.sas” 

a concatenate 92 excel files to create data set WORK.SOIL containing: 

ssaid (soil survey number) 

musym (soil type) 

county_cd 

ddlat (centroid coord, used in diagnostics, discarded in ouput file) 

ddlong (centroid coord, used in diagnostics, discarded in ouput file) 

mtrs 

co_mtrs (a variable that contains errors, it is discarded and recreated as comtrs in 

subsequent processing) 

Total_acres_section (total acres in section) 

Soil_musym_acres (total acres soil type in section) 

3. Create SAS data set called WORK.TEXTURE from ASCII data file MUSYM_texture.lst. 

a. This data file is an SQL download from the ORACLE table Troiano.layer99 (located in 

ORACLE EMON partition). The ASCII file contains variables ssaid,musym, layernum, 

texture and was downloaded taking ONLY layernum=1 (i.e. surface soil). 

b. The variable texture is a code describing main textural class (e.g. sand), textural subclass 

(e.g. coarse sand) and modifier (e.g. gravelly, cobbely etc). 

c. create muid from concatenation of ssaid and musym
Randy Segawa 

January 23, 2009 

Page 8 

4. Run program “get_textureNO_OTHER.sas” 

a. generates corrected comtrs and muid (concatenation of ssaid and musym – the muid is the 

actual soil type code used from here on out). 

b. merge with WORK.FUMI by comtrs iff comtrs is in WORK.FUMI, creating 

WORK.JOIN. This merge is used only to eliminate comtrs where fumigants are not used 

in step d below. Actual fumigant PUR data is merged in the last step of this section as 

described below. 

c. assign main textural class from texture in WORK.TEXTURE. This step removes textural 

class modifiers, creating a variable called class that describes main textural class plus 

sub_class each muid (e.g. VeryFineSandyLoam, LoamyCoarseSand etc.). Note: all 

records missing texture are assigned class=‘OTHER’ (this include sections that are 

missing soil survey data.) Also, nonstandard texture designations such as “variable” or 

“fragments” are assigned class=‘OTHER.’ 

d. merge WORK.JOIN with WORK.TEXTURE by muid; this retains only soil data from 

sections where fumigants are actually used and EXCLUDING class =OTHER. Dataset 

created = WORK.JOIN2. 

e. calculate classfrac (=class fraction) for each class in each comtrs: classfrac = ∑ (acres 

each class in section)/ ∑ (total acres all classes in section). NOTE: as program is 

currently written, the denominator is summed excluding class=other). Dataset created = 

WORK.CLASSFRAC 

f. Merge WORK.CLASSFRAC with WORK.FUMI by comtrs (a one to many merge – 

multiple comtrs listed for each comtrs in WORK.CLASSFRAC). Also note this file 

contains fumigant use data for comtrs that have no class designation because soil survey 

data are not available for every comtrs. These comtrs are assigned classfrac=1 and class

= ‘.’ (i.e. missing data). EXPORT to EXCEL: file=get_textureNO_OTHER.xls. In 

EXCEL, assign class = ‘.’ to class =UNKNOWN.