Soil Genesis SSC 120
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This 4 page Class Notes was uploaded by Rita Feil II on Tuesday September 8, 2015. The Class Notes belongs to SSC 120 at University of California - Davis taught by Randal Southard in Fall. Since its upload, it has received 45 views. For similar materials see /class/191782/ssc-120-university-of-california-davis in Soil Science at University of California - Davis.
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Date Created: 09/08/15
Pedon 5 The pedon 5 series consists of moderately deep to hardpan well and moderately well drained soils that formed in alluvium derived from mixed but dominantly granitic rock sources They are on undulating low terraces with slopes of 0 to 9 percent The mean annual precipitation is about 15 inches and the mean annual temperature is about 61 degrees F TYPICAL PEDON Pedon 5 loam on east facing complex slope of 1 percent in a vineyard at elevation of 40 feet Colors are for dry soil unless otherwise stated When described on May 3 1983 the soil was moist throughout 0 to 6 inches brown 75YR 54 loam dark brown 75YR 34 moist moderate medium and fine subangular blocky structure hard friable slightly sticky and slightly plastic common very ne roots many very fine tubular and interstitial and few fine tubular pores few ne very dark gray 10YR 3 1 FeMi concretions and stains neutral pH 73 clear wavy boundary 5 to 15 inches thick 6 to 10 inches brown 75YR 54 loam reddish brown 5YR 44 moist moderate medium subangular blocky structure hard friable slightly sticky and slightly plastic common very ne roots many very fine tubular and common very ne interstitial pores few thin clay films on ped faces and bridging mineral grains few ne very dark gray 10YR 31 FeMi concretions and stains moderately acid pH 57 clear wavy boundary 0 to 8 inches thick 10 to 16 inches brown 75YR 54 loam reddish brown 5YR 44 moist moderate medium subangular blocky structure very hard friable sticky and plastic many very fine and few fine tubular and common very fine interstitial pores few thin clay films on ped faces common thin clay film bridging mineral grains common light gray 10YR 72 fine sand or silt grains on ped faces and lining pores few fine dark gray 10YR 3 1 FeMi concretions moderately acid pH 59 abrupt wavy boundary 0 to 12 inches thick 16 to 21 inches brown 75YR 54 clay strong brown 75YR 46 moist moderate medium prismatic structure extremely hard firm sticky and very plastic few very ne ne and medium roots common very fine tubular and few very fine interstitial pores common moderately thick clay lms on ped faces many thin clay films bridging mineral grains common slickensides that do not intersect about 3 percent ne very dark gray diameter FeMi concretions neutral pH 70 gradual wavy boundary 4 to 10 inches thick 21 to 26 inches brown 75YR 54 clay dark brown 75YR 44 moist moderate medium prismatic structure extremely hard firm sticky and plastic few very fine ne and medium roots common very fine tubular and few very fine interstitial pores common moderately thick clay films on ped faces and common thin clay lms as bridges between mineral grains about 3 percent very dark gray 10YR 3 1 FeMi concretions and stains neutral pH 73 abrupt wavy boundary 3 to 5 inches thick 26 to 29 inches variegated brown 75YR 54 and light brown 75YR 64 duripan brown 75YR 44 moist extremely hard and brittle silica and sesquioxide cementation in more than 90 percent of the matrix few fine FeMi concretions strongly effervescent with secondary lime in fractures common very fine close tubular pores moderately alkaline pH 80 gradual smooth boundary 1 to 10 inches thick 29 to 48 inches variegated brown 75YR 54 and strong brown 75YR 46 duripan dark brown 75YR 34 moist extremely hard and brittle silica and sesquioxide cementation in more than 90 percent of the matrix common fine FeMi concretions and stains strongly effervescent with segregated lime in fractures common very ne closed tubular pores moderately alkaline pH 80 clear wavy boundary 1 to 25 inches thick 48 to 60 inches brown 75YR 54 duripan dark brown 75YR 34 moist extremely hard and brittle silica and sesquioxide cementation in 70 to 90 percent of matrix common fine FeMi concretions many very fine interstitial pores moderately alkaline pH 80 TYPE LOCATION Pedon 5 County California about 5 miles northeast of Lodi 3700 feet west of intersection of Southern Pacific Railroad and Forest Lake Road 1100 feet south of Forest Lake Road and about 100 feet west into vineyard 1700 feet north and 2600 feet east of the southwest corner of sec 3 T 4 N R 6 E MDBampM Lodi North quadrangle SSC 120 Water Balance 2 PART 1 For the two locations below calculate the water balance Graph the ETp potential evapotranspiration and P precipitation against months of the year On each graph identify regions of deficit D recharge R surplus S and utilization U of soil water Remember that the soil will store water up to its WHC water holding capacity any excess is surplus surplus does not accumulate from one month to the next During utilization of stored water storage does not go below zero Once ETp exceeds P utilization begins Identify the probable soil moisture and temperature regimes from Soil Taxonomy Remember to add 1 C to the air temperature data to estimate MAST Compare and discuss the potential for weathering and leaching at the two locations What are the possible disadvantages of using longterm average precipitation data to predict leaching Is a comparison between locations of only total precipitation sufficient to predict leaching and weathering potential Explain SOIL A WHC 200 mm J F M A M J J A S O N D TOT T C 23 23 23 24 25 26 26 25 25 24 24 23 ETp mm 81 74 94 101 131 144 150 148 130 124 108 97 P mm 55 40 52 77 74 61 108 137 182 141 126 98 PETp Storage Surplus SOIL B WHC 275 mm J F M A M J J A S O N D TOT T C 8 9 10 12 14 18 23 22 20 15 9 8 ETp mm 20 24 32 48 74 102 124 117 73 47 31 21 P mm 221 204 179 94 64 21 0 0 23 47 108 202 PETp Storage Surplus PART 2 For soil A calculate or show in a graph the depth of wetting in the soil as a function of month of the year In this case assume that the soil consists of sandy loam material with a water holding capacity of 01 cm water10 cm of soil that all of the precipitation comes in one event at the beginning of the month that there is no run off and that wetting leaching occurs only in months when PgtETp What would happen to depth of wetting if the soil material is a very gravelly sandy loam with 50 by volume rock fragments assuming that the rock fragments hold no water and other assumptions from above Discuss the importance of your results with respect to the how parent material can affect leaching and weathering as soil forming processes Pedon 24 Page 1 of1 The Pedon 24 consists of moderately deep moderately well drained soilsthat formed in alluvium from mixed sources Profile 24 soils are on terraces and basin rims and have slopes of 0 to 2 percent The mean annual precipitation is 18 inches and the mean annual temperature is 62 degrees F TAXONOMIC CLASS TYPICAL PEDON Pedon 24 loam on a basin rim of about 1 percent slope under a harvested field of irrigated rice at 34 feet elevation Colors are for dry soil unless othenNise stated When described on April 10 1979 the soil was dry to 2 inches and moist below 0 to 5 inches light yellowish brown 10YR 64 loam dark yellowish brown 10YR 34 moist few medium distinct reddish yellow 75YR 68 mottles strong brown 75YR 58 moist weak coarse subangular blocky structure hard friable sticky and plastic common very fine roots common very fine and fine tubular pores common fine and medium manganese concretions medium acid pH 60 gradual wavy boundary 5 to 12 inches thick 5 to 10 inches pale brown 10YR 63 loam brown 10YR 43 moist few medium distinct reddish yellow 75YR 78 mottles red 25YR 48 moist weak coarse suba ngular blocky structure hard friable sticky and plastic common very fine roots common very fine and fine tubular pores common fine and medium manganese concretions medium acid pH 60 gradual wavy boundary 5 to 8 inches thick 1 0 to 16 inches light yellowish brown 10YR 64 loam brown 75YR 44 moist weak coarse suba ngular blocky structure hard firm sticky and plastic common very fine roots common very fine tubular pores common fine and medium manganese concretions moderately alkaline pH 80 abrupt irregular boundary 4 to 8 inches thick 1 6 to 24 inches pink 75YR 84 clay yellowish red 5YR 46 moist moderate coarse angular blocky structure very hard firm very sticky and plastic few very fine tubular pores common fine manganese concretions and stains common pressure faces moderately alkaline pH 80 abrupt smooth boundary 6 to 12 inches thick 24 to 38 inches very pale brown 10YR 74 duripan reddish yellow 75YR 66 moist massive continuously indurated byl cm laminar silica cap strongly effervescent with laminar capping of lime common manganese and iron stains in seams below capping moderately alkaline pH 80 abrupt smooth boundary 2 to 16 inches thick 38 to 60 inches light gray 10YR 72 weakly consolidated siltstone Slakes in water TYPE LOCATION Sutter County California approximately 32 miles south of Tudor on US Highway 99 then 06 miles west on farm road adjacent to Wilson School then 300 feet north into rice field 300 feet north and 200 feet west ofthe southeast corner Section 15 T l 3 N R 3 E RANGE IN CHARACTERISTICS The mean annual soil temperature is 60 degrees to 65 degrees F The soil temperature is above 47 degrees F the entire year The difference between mean summer and mean winter soil temperature is 30 degrees to 33 degrees F The soil between depths of 6 and 18 inches is usually dry in all parts from June through October and is moist in some or all parts from Novemberthrough May GEOGRAPHIC SETTING Pedon 24 soils are on old remnant terraces and basin rims Slopes are 0 to 2 percent The soils formed in alluvium from mixed sources deposited over unrelated siltstone Elevations are 20 to 80 feet Climate is subhumid with hot dry summers and cool moist winters Mean annual precipitation is l 7 to 20 inches Mean January temperature is 77 degrees F mean Julytemperature is 45 degrees F and mean annual temperature is 60 degrees to 64 degrees F Frostfree season is 260 to 280 days DRAINAGE AND PERMEABILITY Moderatelywell drained very slow to slow runoff moderate oververy slow permeability Some areas ofthis soil are subject to frequent brief to long periods of flooding in December through April A perched watertable is at a depth of l 8 to 36 inches in Decemberthrough April GEOLOGIC TIME SCALE lt1 YEARS E PERIOD EPOCH BEFORE CALIFORNIA EVENTS P R E S E N T Holocene PostModesto Formation gt Post Glacial 11 000 Post Glacial lt10kya 24 Modesto Formation lO40kya a Riverbank Formation 100 E Pleistocene 300kya Q Glacial Turlock Lake Formation 500 Q a 700kya 5 Laguna Formation 1600 g 1 800 000 2000kya a E Pliocene Sierran volcanism Q U 5 300 000 gt4 0 m Mlocene Mehrten Formation lt E I 23 800 000 I I I E E Oligocene 33 700 000 Vallev Sprlngs volcan1c episode m 4 Goldbearing gravels m U Eocene F 8 54 800 000 Ione Formation g Paleocene 65 000 000 Cretaceous 144 000 000 D1nosaurs 8 Jurassic Sierran Nevada batholith w 206 000 000 a 2 Triass1c 248 000 000 Permian 290 000 000 O a P 1 39 2 g a g ennsy vaman 323 000 000 8 5 E O Mississippian a 354 000 000 j Devonian 417 000 000 Land plants A Silurian 443 000 000 Ordovician 490 000 000 Cambrian Ancestral Sierran metamorphic 540 000 000 rocks PRECAMBRIAN
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