Soil Data Explorer - POSITAS

Official Series Description

Lab Data Summary

Aggregate lab data for the POSITAS soil series. This aggregation is based on all pedons with a current taxon name of POSITAS, and applied along 1-cm thick depth slices. Solid lines are the slice-wise median, bounded on either side by the interval defined by the slice-wise 5th and 95th percentiles. The median is the value that splits the data in half. Five percent of the data are less than the 5th percentile, and five percent of the data are greater than the 95th percentile. Values along the right hand side y-axis describe the proportion of pedon data that contribute to aggregate values at this depth. For example, a value of "90%" at 25cm means that 90% of the pedons correlated to POSITAS were used in the calculation. Source: KSSL snapshot (updated 2020-03-18). Methods used to assemble the KSSL snapshot used by SoilWeb / SDE

Pedons used in the lab summary:

MLRA	Lab ID	Pedon ID	Taxonname	CI	NSSL / NASIS Reports	Link To SoilWeb GMap
14	40A2928	S1959CA001001	POSITAS	5	Primary | Supplementary | Taxonomy | Pedon | Water Retention | Correlation | Andic Soil Properties	37.6502762,-121.6961136
14	40A2929	S1959CA001002	POSITAS	5	Primary | Supplementary | Taxonomy | Pedon | Water Retention | Correlation | Andic Soil Properties	37.6255569,-121.7852783

Water Balance

Monthly water balance estimated using a leaky-bucket style model for the POSITAS soil series. Monthly precipitation (PPT) and potential evapotranspiration (PET) have been estimated from the 50th percentile of gridded values (PRISM 1981-2010) overlapping with the extent of SSURGO map units containing each series as a major component. Monthly PET values were estimated using the method of Thornthwaite (1948). These (and other) climatic parameters are calculated with each SSURGO refresh and provided by the fetchOSD function of the soilDB package. Representative water storage values (“AWC” in the figures) were derived from SSURGO by taking the 50th percentile of profile-total water storage (sum[awc_r * horizon thickness]) for each soil series. Note that this representation of “water storage” is based on the average ability of most plants to extract soil water between 15 bar (“permanent wilting point”) and 1/3 bar (“field capacity”) matric potential. Soil moisture state can be roughly interpreted as “dry” when storage is depleted, “moist” when storage is between 0mm and AWC, and “wet” when there is a surplus. Clearly there are a lot of assumptions baked into this kind of monthly water balance. This is still a work in progress.

Sibling Summary

Siblings are those soil series that occur together in map units, in this case with the POSITAS series. Sketches are arranged according to their subgroup-level taxonomic structure. Source: SSURGO snapshot (updated 2024-02-21), parsed OSD records (updated 2023-10-06) and snapshot of SC database (updated 2023-10-02).

Select annual climate data summaries for the POSITAS series and siblings. Series are sorted according to hierarchical clustering of median values. Source: SSURGO map unit geometry and 1981-2010, 800m PRISM data (updated 2023-10-09).

Geomorphic description summaries for the POSITAS series and siblings. Series are sorted according to hierarchical clustering of proportions and relative hydrologic position within an idealized landform (e.g. top to bottom). Most soil series (SSURGO components) are associated with a hillslope position and one or more landform-specific positions: hills, mountain slopes, terraces, and/or flats. Proportions can be interpreted as an aggregate representation of geomorphic membership. The values printed to the left (number of component records) and right (Shannon entropy) of stacked bars can be used to judge the reliability of trends. Small Shannon entropy values suggest relatively consistent geomorphic association, while larger values suggest lack thereof. Source: SSURGO component records (updated 2023-10-04).

Competing Series

Soil series competing with POSITAS share the same family level classification in Soil Taxonomy. Source: parsed OSD records (updated 2023-10-06) and snapshot of the SC database (updated 2023-10-02).

Select annual climate data summaries for the POSITAS series and competing. Series are sorted according to hierarchical clustering of median values. Source: SSURGO map unit geometry and 1981-2010, 800m PRISM data (updated 2023-10-09).

Geomorphic description summaries for the POSITAS series and competing. Series are sorted according to hierarchical clustering of proportions and relative hydrologic position within an idealized landform (e.g. top to bottom). Proportions can be interpreted as an aggregate representation of geomorphic membership. Most soil series (SSURGO components) are associated with a hillslope position and one or more landform-specific positions: hills, mountain slopes, terraces, and/or flats. The values printed to the left (number of component records) and right (Shannon entropy) of stacked bars can be used to judge the reliability of trends. Shannon entropy values close to 0 represent soil series with relatively consistent geomorphic association, while values close to 1 suggest lack thereof. Source: SSURGO component records (updated 2023-10-04).

There are insufficient data to create the 3D mountains figure.

There are insufficient data to create the 3D flats position figure.

Soil series sharing subgroup-level classification with POSITAS, arranged according to family differentiae. Hovering over a series name will print full classification and a small sketch from the OSD. Source: snapshot of SC database (updated 2023-10-02).

Block Diagrams

Click a link below to display the diagram. Note that these diagrams may be from multiple survey areas.

1. CA-2012-05-08-17 | Alameda Area - March 1966

   The relationship of geologic formations, landforms, and soil series in the Alameda Area (Soil Survey of Alameda Area, California; March, 1966).

Map Units

Map units containing POSITAS as a major component. Limited to 250 records.

Map Unit Name	Symbol	Map Unit Area (ac)	Map Unit Key	National Map Unit Symbol	Soil Survey Area	Publication Date	Map Scale
Goldeagle-Positas-Balcom complex, 30 to 75 percent slopes	275	32913	461618	hhbx	ca011	1999	1:24000
Positas gravelly sandy loam, 30 to 50 percent slopes	276	5950	461619	hhby	ca011	1999	1:24000
Positas loam, 0 to 2 percent slopes	PkA	1310	455839	h9bh	ca013	1973	1:24000
Positas loam, 2 to 9 percent slopes	PkC	760	455840	h9bj	ca013	1973	1:24000
Positas gravelly loam, 0 to 9 percent slopes	PsC	1097	459849	hfhv	ca097	1968	1:20000
Positas gravelly loam, 9 to 15 percent slopes	PsD	330	459850	hfhw	ca097	1968	1:20000
Positas gravelly loam, 30 to 50 percent slopes, eroded	PfF2	8251	459257	hdwr	ca113	1968	1:20000
Positas gravelly loam, 30 to 50 percent slopes, severely eroded	PfF3	4595	459258	hdws	ca113	1968	1:20000
Positas gravelly loam, 15 to 30 percent slopes, eroded	PfE2	2073	459256	hdwq	ca113	1968	1:20000
Positas gravelly loam, 2 to 20 percent slopes, eroded	PoC2	8984	456610	hb4c	ca609	1963	1:20000
Positas gravelly loam, 20 to 40 percent slopes, eroded	PoE2	8179	456611	hb4d	ca609	1963	1:20000
Positas gravelly loam, 40 to 60 percent slopes, eroded	PoF2	3335	456612	hb4f	ca609	1963	1:20000
Positas gravelly loam, thick surface, 2 to 10 percent slopes, eroded	PtB2	2271	456613	hb4g	ca609	1963	1:20000
Positas gravelly clay loam, 2 to 15 percent slopes	PaD	941	463290	hk2v	ca649	1967	1:24000
Positas gravelly loam, 30 to 45 percent slopes	PzaE	671	464427	hl8j	ca654	1966	1:24000
Positas gravelly loam, 9 to 30 percent slopes	PzaD	396	464426	hl8h	ca654	1966	1:24000
Positas gravelly loam, 3 to 9 percent slopes	PzaB	296	464425	hl8g	ca654	1966	1:24000
Arbuckle-Positas complex, 9 to 15 percent slopes	102	16365	457205	hbrk	ca665	1977	1:24000
Arbuckle-Positas complex, 15 to 30 percent slopes	103	13345	457206	hbrl	ca665	1977	1:24000
Arbuckle-Positas complex, 30 to 50 percent slopes	104	5835	457207	hbrm	ca665	1977	1:24000
Arbuckle-Positas complex, 50 to 75 percent slopes	105	4545	457208	hbrn	ca665	1977	1:24000
Positas fine sandy loam, 2 to 9 percent slopes	PtC	6458	457471	hc14	ca672	1966	1:20000
Positas fine sandy loam, 9 to 15 percent slopes	PtD	3113	457472	hc15	ca672	1966	1:20000
Positas fine sandy loam, 15 to 30 percent slopes	PtE	1345	457474	hc17	ca672	1966	1:20000
Positas cobbly fine sandy loam, 2 to 15 percent slopes	PuD	657	457475	hc18	ca672	1966	1:20000
Positas fine sandy loam, 9 to 15 percent slopes, severely eroded	PtD3	176	457473	hc16	ca672	1966	1:20000
Milpitas-Positas fine sandy loams, 2 to 9 percent slopes	MeC	5585	457625	hc63	ca673	1974	1:24000
Milpitas-Positas fine sandy loam, 9 to 15 percent slopes, eroded	MeD2	4881	457626	hc64	ca673	1974	1:24000
Milpitas-Positas fine sandy loams, 15 to 30 percent slopes, eroded	MeE2	1574	457627	hc65	ca673	1974	1:24000
Milpitas-Positas fine sandy loams, 30 to 50 percent slopes, eroded	MeF2	640	457628	hc66	ca673	1974	1:24000
Positas-Bitcreek complex, 2 to 9 percent slopes	600	2864	466570	hnhn	ca691	2008	1:24000
Positas fine sandy loam, 9 to 15 percent slopes, severely eroded	PtD3	28	1412883	1jf6w	ca772	1981	1:24000
Positas cobbly fine sandy loam, 2 to 15 percent slopes	PuD	15	1412884	1jf6x	ca772	1981	1:24000
Arbuckle-Positas complex, 9 to 15 percent slopes	102pr	4	1412868	1jf6d	ca772	1981	1:24000

Map of Series Extent

Approximate geographic distribution of the POSITAS soil series. To learn more about how this distribution was mapped, or to compare this soil series extent to others, use the Series Extent Explorer (SEE) application. Source: generalization of SSURGO geometry (updated 2023-10-04).