Common soil textures in Yolo County. Symbol size denotes relative abundance. The orange symbol represents a weighted average for the entire county.
Davis soils vary from moderately sandy (Reiff Series) in south and East Davis, through loamy soils (Yolo Series) in Central Davis, to heavy clay soils (Caypay Series) in west and North Davis. The spatial variation of soil properties in Davis is directly related to the fluvial deposition histories of the nearby streams. The heavy soils are found where low velocity waters of Putah Creek deposited material from the Coast Range. This material is notorious for having high concentrations of exotic elements; however the local high concentration of the element Boron is most likely from ground water. Sandier soils are found in locations where depositional energies were higher, or where material from the Sierra Nevada was incorporated. For specifics on the type of soil at your address, check out the UC Davis Soil Resource Lab's Online Soil Survey.
Use as a growth media
The soils found in and around Davis are often thought of as a poor growth medium. While this may be true for an uncultivated parcel of land where one attempts to plant seedlings by hand, but in terms of water storage capacity and nutrient storage the soils found here are some of the most productive in the world. The surface cracking observed in the summer is a result of the high content of smectitic clays, derived from weathered Coast Range rocks. The shrinking and swelling effects of these heavy clay soils (Capay Series) not only make it difficult to plant a vegetable garden, but also wreak havoc on houses or permanent structures. By incorporating copious amounts of mulch it is possible to create a rooting environment hospitable for seedlings, while retaining the high water holding capacity and nutrient store that the local soils offer. Similarly, you can lower the rate at which house plants dry out by incorporating a small amount of local soil into existing potting mix.
pH issues
The pH of soils found in and around the city of Davis range from neutral (7) to alkaline (> 8.5). While this condition does not affect plants native to this region, many plants may not be able to readily access several key micronutrients at this pH. As a general rule of thumb, a pH near 8.2 suggests that CaCO3 is the main buffering agent, and at pH near 8.5 Na2CO3 is the main buffering agent. It is very common in this region for soils with a high pH to also have a high sodium content as well. The sodium is usually more toxic than the high pH, although at higher pH values important micro nutrients such as Iron are less available to plants.
If you were to draw a rectangle around all of Davis and surrounding sprawl you would find that on a per-area basis only about 16% of the land has a moderately alkaline pH value (Yolo County Soil Survey).
| Acres of Land |
| Percent of Total Area |
| Maximum pH (all horizons) |
| 0.54 |
| 6.2 |
| 1637 |
| 1.54 |
| 7.2 |
| 1845 |
| 1.65 |
| 7.3 |
| 4091 |
| 6.11 |
| 8.5 |
| 6574 |
| 9.95 |
| 8.8 |
| 14486 |
| 14.57 |
| 8.2 |
| 19694 |
| 21.77 |
| 7.9 |
| 36891 |
| 51.54 |
| 7.5 |
Expected Shrink-Swell by Map Unit
Soils in Yolo County, as tabulated by expected Linear Extensibility Percent (lep).
musym | name | acres | lep | lep_class -------+------------------------------------------------------------------+---------+------+----------- Ya | Yolo silt loam | 39698 | 2.52 | Low Sc | Sacramento clay | 34886 | 7.50 | High Ca | Capay silty clay | 33465 | 7.50 | High MrG2 | Millsholm rocky loam, 15 to 75 percent slopes, eroded | 30118 | 1.50 | Low Rg | Rincon silty clay loam | 24580 | 6.36 | High BrA | Brentwood silty clay loam, 0 to 2 percent slopes | 23045 | 7.50 | High CtD2 | Corning gravelly loam, 2 to 15 percent slopes, eroded | 22080 | 5.34 | Moderate Mf | Marvin silty clay loam | 20970 | 6.60 | High DaF2 | Dibble clay loam, 30 to 50 percent slopes, eroded | 18612 | 7.11 | High SmE2 | Sehorn-Balcom complex, 15 to 30 percent slopes, eroded | 17794 | 6.17 | High TaA | Tehama loam, 0 to 2 percent slopes | 16622 | 3.75 | Moderate BdF2 | Balcom-Dibble complex, 30 to 50 percent slopes, eroded | 16405 | 5.73 | Moderate SmD | Sehorn-Balcom complex, 2 to 15 percent slopes | 16117 | 6.50 | High BaF2 | Balcom silty clay loam, 30 to 50 percent slopes, eroded | 12637 | 4.50 | Moderate Sg | Sacramento soils, flooded | 12258 | 6.27 | High Cn | Clear Lake soils, flooded | 11666 | 6.92 | High SmF2 | Sehorn-Balcom complex, 30 to 50 percent slopes, eroded | 11226 | 6.33 | High Cc | Capay soils, flooded | 11030 | 7.50 | High Sv | Sycamore complex, drained | 9241 | 4.18 | Moderate Ms | Myers clay | 8938 | 7.50 | High PfF2 | Positas gravelly loam, 30 to 50 percent slopes, eroded | 7920 | 5.34 | Moderate St | Sycamore silty clay loam, drained | 7839 | 4.50 | Moderate Ck | Clear Lake clay | 6946 | 7.50 | High Ra | Reiff very fine sandy loam | 6847 | 1.50 | Low SkD | Sehorn clay, 2 to 15 percent slopes | 6069 | 7.50 | High Sp | Sycamore silt loam, drained | 6054 | 3.42 | Moderate Sa | Sacramento silty clay loam | 6023 | 6.27 | High DbG2 | Dibble-Millsholm complex, 50 to 75 percent slopes, eroded | 5846 | 5.24 | Moderate Wb | Willows clay | 5624 | 7.50 | High Sw | Sycamore complex, flooded | 5517 | 4.18 | Moderate Ss | Sycamore silty clay loam | 5489 | 4.50 | Moderate Pb | Pescadero silty clay, saline-alkali | 5281 | 7.50 | High BaE2 | Balcom silty clay loam, 15 to 30 percent slopes, eroded | 5192 | 4.50 | Moderate Yb | Yolo silty clay loam | 5040 | 4.50 | Moderate PfF3 | Positas gravelly loam, 30 to 50 percent slopes, severely eroded | 4584 | 6.00 | High So | Sycamore silt loam | 4474 | 3.42 | Moderate Rh | Riverwash | 4369 | 1.50 | Low Sh | San Ysidro loam | 4289 | 4.44 | Moderate HcA | Hillgate loam, 0 to 2 percent slopes | 4029 | 5.19 | Moderate Tb | Tyndall very fine sandy loam | 3726 | 1.50 | Low Pc | Pescadero soils, flooded | 3589 | 5.22 | Moderate Za | Zamora loam | 3466 | 3.75 | Moderate Ob | Omni silty clay | 3342 | 7.50 | High Su | Sycamore complex | 3206 | 4.14 | Moderate La | Lang sandy loam | 3001 | 1.50 | Low Wc | Willows clay, alkali | 2929 | 7.50 | High DaG2 | Dibble clay loam, 50 to 75 percent slopes, eroded | 2874 | 7.11 | High Wf | Willows clay, alkali, flooded | 2816 | 7.50 | High Te | Tyndall very fine sandy loam, deep | 2709 | 1.50 | Low Sb | Sacramento silty clay loam, drained | 2663 | 6.27 | High Cb | Capay silty clay, flooded | 2410 | 7.50 | High AaA | Arbuckle gravelly loam, 0 to 2 percent slopes | 2391 | 3.48 | Moderate Sd | Sacramento clay, drained | 2384 | 7.50 | High HdA | Hillgate loam, moderately deep, 0 to 2 percent slopes | 2367 | 3.63 | Moderate Mk | Merritt silty clay loam | 2289 | 3.57 | Moderate Sr | Sycamore silt loam, flooded | 2256 | 3.42 | Moderate Vb | Valdez silt loam, deep | 2222 | 3.42 | Moderate Sn | Soboba gravelly sandy loam | 2205 | 1.50 | Low Lg | Laugenour very fine sandy loam | 2202 | 1.50 | Low SlD | Sehorn cobbly clay, 2 to 15 percent slopes | 2163 | 7.50 | High SkF2 | Sehorn clay, 30 to 50 percent slopes, eroded | 2155 | 7.50 | High Lb | Lang sandy loam, deep | 2123 | 1.50 | Low Mn | Merritt silty clay loam, deep | 2112 | 3.57 | Moderate 163n | Maymen-Millsholm-Lodo association, 30-75 percent slopes | 2092 | 2.25 | Low PfE2 | Positas gravelly loam, 15 to 30 percent slopes, eroded | 2072 | 5.34 | Moderate Tc | Tyndall very fine sandy loam, drained | 1989 | 1.50 | Low Rb | Reiff gravelly loam | 1914 | 1.50 | Low Mo | Merritt silty clay loam, deep, drained | 1858 | 3.57 | Moderate DbF2 | Dibble-Millsholm complex, 30 to 50 percent slopes, eroded | 1788 | 4.47 | Moderate SkE2 | Sehorn clay, 15 to 30 percent slopes, eroded | 1775 | 7.50 | High Lm | Loamy alluvial land | 1708 | 1.50 | Low Md | Maria silt loam, deep | 1661 | 3.51 | Moderate Mb | Maria silt loam | 1644 | 3.51 | Moderate Wa | Willows silty clay loam | 1458 | 6.36 | High Wm | Willows clay, marly variant | 1420 | 7.50 | High HcC2 | Hillgate loam, 2 to 9 percent slopes, eroded | 1385 | 5.10 | Moderate Wg | Willows soils, flooded | 1331 | 5.97 | Moderate AaB | Arbuckle gravelly loam, 2 to 5 percent slopes | 1326 | 3.48 | Moderate TaB | Tehama loam, 2 to 5 percent slopes | 1242 | 3.75 | Moderate Lk | Laugenour very fine sandy loam, deep, flooded | 1180 | 1.50 | Low Lh | Laugenour very fine sandy loam, flooded | 1172 | 1.50 | Low Rk | Riz loam | 1166 | 6.00 | High CtE2 | Corning gravelly loam, 15 to 30 percent slopes, eroded | 1063 | 5.34 | Moderate HdC | Hillgate loam, moderately deep, 2 to 9 percent slopes | 1060 | 3.63 | Moderate Mp | Merritt complex, saline-alkali | 897 | 3.57 | Moderate DbE2 | Dibble-Millsholm complex, 9 to 30 percent slopes, eroded | 804 | 5.13 | Moderate Mc | Maria silt loam, flooded | 793 | 3.51 | Moderate Rn | Riz loam, flooded | 787 | 6.00 | High Ld | Lang silt loam | 744 | 1.50 | Low Tf | Tyndall silty clay loam | 741 | 2.25 | Low Pa | Pescadero silty clay | 727 | 7.50 | High Td | Tyndall very fine sandy loam, flooded | 684 | 1.50 | Low 114n | Bressa-Dibble complex, 30 to 50 percent slopes | 666 | 4.15 | Moderate Sf | Sacramento clay, deep | 645 | 7.50 | High Vc | Valdez complex, flooded | 645 | 3.42 | Moderate Va | Valdez silt loam | 581 | 3.42 | Moderate Wd | Willows clay, alkali, drained | 566 | 7.50 | High Wn | Willows clay, marly variant, saline-alkali | 553 | 7.50 | High Se | Sacramento clay, flooded | 544 | 7.50 | High Oa | Omni silty clay loam | 523 | 6.60 | High Ch | Clear Lake silty clay loam | 402 | 5.97 | Moderate 142l | Henneke-Montara-Rock outcrop complex, 15 to 50 percent slopes | 366 | 4.50 | Moderate CrE2 | Climara clay, 2 to 30 percent slopes, eroded | 333 | 7.50 | High BaD3 | Balcom silty clay loam, 5 to 15 percent slopes, severely eroded | 312 | 4.50 | Moderate 154n | Henneke gravelly loam, 30 to 75 percent slopes | 303 | 3.08 | Moderate Lc | Lang sandy loam, deep, flooded | 280 | 1.50 | Low BaG3 | Balcom silty clay loam, 50 to 75 percent slopes, severely eroded | 264 | 4.50 | Moderate 112c | Westfan loam, 0 to 2 percent slopes | 260 | 3.42 | Moderate 115c | Clear Lake clay, 0 to 1 percent slopes,occasionally flooded | 160 | 9.59 | Very High 166n | Montara clay loam, 5 to 30 percent slopes | 145 | 4.50 | Moderate 115n | Bressa-Dibble complex, 50 to 75 percent slopes | 142 | 4.12 | Moderate 320c | Millsholm loam, 5 to 30 percent slopes | 113 | 1.92 | Low 160c | Grandbend loam, 0 to 2 percent slopes | 107 | 4.27 | Moderate 127c | Mallard clay loam, 0 to 1 percent slopes | 100 | 5.93 | Moderate 174l | Maymen-Hopland-Mayacama association, 50 to 75 percent slopes | 66 | 2.75 | Low GP | Gravel pits | 61 | 1.50 | Low 114c | Westfan clay loam, 0 to 1 percent slopes | 59 | 4.58 | Moderate 188c | Westfan loam, clay substratum, 0 to 2 percent slopes | 58 | 4.32 | Moderate 173l | Maymen-Hopland-Mayacama association, 30 to 50 percent slopes | 42 | 2.75 | Low 280c | Skyhigh-Millsholm complex, 15 to 50 percent slopes | 24 | 3.59 | Moderate 171l | Maymen-Hopland-Etsel association, 15 to 50 percent slopes | 24 | 2.43 | Low 129c | Mallard clay loam, 0 to 1 percent slopes, occasionally flooded | 21 | 5.80 | Moderate 108c | Scribner silt loam, 0 to 1 percent slopes | 20 | 2.86 | Low 129n | Diablo clay, 30 to 50 percent slopes | 7 | 7.50 | High 165n | Millsholm loam, 30 to 75 percent slopes | 7 | 1.50 | Low
