It will be observed that according to Maercker’s valuation, the average California soil is “rich” in potash and lime, but only “medium” as regards its contents of phosphoric acid and nitrogen. In this respect, and almost throughout, Maercker’s ratings are in remarkable agreement with those made by the writer as far back as 1860.[124] It also appears that Maercker’s figures for “normal” soils correspond to those of the American humid regions; the “arid” figures for potash and lime being “abnormally” high.
Unfortunately neither Maercker’s method of preparing the soil extract, nor his ratings as given in the table, are accepted by all soil chemists even in Germany. As will be seen by reference to Wohltmann’s work on the soils of Samoa and Kamerun ([chap. 21, p. 404]), his methods and numerical estimates differ widely from those given by Maercker, and also from those adopted by the Prussian soil surveys. Reference to the analyses of the soils of Madagascar by Müntz and Rousseaux, given in the same chapter, [page 406], shows still another different method, although as it happens their numerical estimates do not differ very widely from those of Wohltmann. In both cases, a special, more incisive extraction is made for the determination of potash. Why the same more energetic action is not used for the other ingredients also, is not stated, and is obscure. Fortunately, in all cases the action is at least sufficiently strong to secure the dissolution of all the lime existing in the form of carbonate, and of all, or nearly all, the phosphoric acid not securely locked up as ferric phosphate; the latter being inert, is of no special interest (see Analyses of Hawaiian Soils, this chapter, [page 256]).
CHAPTER XX.
SOILS OF THE ARID
AND HUMID[125] REGIONS.
Composition of Good Medium Soils.—In the preceding tables examples have been given of rather extreme types of soils, both rich and poor throughout, and also of such as are deficient in one or several of the important ingredients. In the table below are given the analyses of some of the good average farming lands; uplands of several states, both of the humid and arid regions. In the former, the representative timber trees of such lands are the black, red, white and (less characteristically) the post, black-jack, Spanish, overcup and locally some other oaks; grading higher in proportion to the presence of more or less hickory, and lower as the latter is replaced by pine. In the states south of Ohio, the “oak and hickory uplands” are what the farmer usually looks for, outside of the valleys or bottoms.
Criteria of Lands of the Two Regions.—In the country west of the Rocky Mountains, the timber, while locally very characteristic, cannot be as broadly used as a criterion, partly on account of its scarcity, partly because the dominant factor in the growth of trees is moisture, which is measurably independent of chemical soil-composition. The latter, moreover, on account of climatic conditions, already alluded to ([chapter 16]), does not vary as materially in the arid as the humid region, on account of the almost universal presence of larger proportions of lime carbonate; the variations of which in the humid region govern largely the vegetative changes. For we there find the timber growth of the lowlands ascending into the uplands so soon as the latter becomes decidedly calcareous; as is abundantly exemplified in the loess or “bluff” formations bordering the Mississippi, Ohio, and Missouri rivers, where the black walnut, tulip tree, ash, honey-locust, together with the lowland oaks, hickories and cane usually characterizing the stream bottoms, grow abundantly and with luxuriant development on the adjoining steep hill country as well (see below, chapters 24, 25).
UPLAND SOILS OF HUMID REGION.
| Oak Uplands with Hickory and Walnut. | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| State. | Tennessee. | Mississippi. | Alabama. | Georgia. | |||||
| County. | Rutherford | Pontotoc | Benton | Cherokee | Polk | ||||
| Number of Sample | 7 | 226 | 216 | 110 | 502 | ||||
| Chemical Analysis of Fine Earth. | |||||||||
| Insoluble matter | 75.35 | 82.66 | 83.27 | 88.83 | 83.35 | 78.73 | 84.77 | 72.32 | 76.55 |
| Soluble silica | 7.31 | 5.56 | 6.04 | 4.23 | |||||
| Potash (K₂O) | .26 | .37 | .55 | .26 | .73 | ||||
| Soda (Na₂O) | .26 | .22 | .08 | .12 | .17 | ||||
| Lime (CaO) | .34 | .28 | .25 | .33 | .29 | ||||
| Magnesia (MgO) | .30 | .23 | .48 | .40 | .26 | ||||
| Bro. ox. of Manganese (Mn₃O₄) | .04 | .28 | .76 | .22 | .18 | ||||
| Peroxid of Iron (Fe₂O₃) | 5.18 | 2.39 | 4.80 | 3.71 | 6.29 | ||||
| Alumina (Al₂O₃) | 5.57 | 4.51 | 6.28 | 5.08 | 7.10 | ||||
| Phosphoric acid (P₂O₅) | .08 | .08 | .07 | .09 | .26 | ||||
| Sulfuric acid (SO₃) | .08 | .02 | .06 | .10 | .11 | ||||
| Carbonic acid (CO₂) | |||||||||
| Water and organic matter | 5.50 | 3.11 | 4.20 | 5.15 | 6.60 | ||||
| Total | 99.77 | 100.32 | 100.88 | 100.23 | 99.54 | ||||
| Humus | |||||||||
| “ Ash | |||||||||
| Hygroscopic Moisture | 7.29 | 4.08 | 6.84 | 4.50 | 8.71 | ||||
| absorbed at°C | 22°C | 18°C | |||||||
| Short-leaved Pine.. | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| State. | North Carolina | South Carolina | Mississippi | Louisiana | ||||||
| County. | Cabarrus | Spartan- burgh | Sumner | Franklin | Morehouse | |||||
| Number of Sample | 9 | 5 | 142 | 71 | 232 | |||||
| Chemical Analysis of Fine Earth. | ||||||||||
| Insoluble matter | 78.79 | 86.19 | 43.74 | 49.61 | 90.23 | 92.55 | 88.75 | 90.56 | 81.70 | 87.45 |
| Soluble silica | 7.40 | 5.87 | 2.32 | 1.81 | 5.75 | |||||
| Potash (K₂O) | .13 | .21 | .24 | .14 | .44 | |||||
| Soda (Na₂O) | .01 | .09 | .09 | .09 | .27 | |||||
| Lime (CaO) | .34 | .03 | .09 | .07 | .10 | |||||
| Magnesia (MgO) | .31 | .21 | .20 | .19 | .24 | |||||
| Bro. ox. of Manganese (Mn₃O₄) | .05 | .01 | .07 | .08 | .39 | |||||
| Peroxid of Iron (Fe₂O₃) | 4.99 | 11.70 | 1.84 | 2.41 | 3.55 | |||||
| Alumina (Al₂O₃) | 4.02 | 26.54 | 1.86 | 2.20 | 4.87 | |||||
| Phosphoric acid (P₂O₅) | .14 | .13 | .09 | .08 | .10 | |||||
| Sulfuric acid (SO₃) | .08 | .01 | .01 | .01 | .08 | |||||
| Carbonic acid (CO₂) | ||||||||||
| Water and organic matter | 3.88 | 11.60 | 2.83 | 4.31 | 2.54 | |||||
| Total | 100.14 | 100.22 | 99.87 | 100.14 | 100.03 | |||||
| Humus | ||||||||||
| “ Ash | ||||||||||
| Hygroscopic Moisture | 3.65 | 11.21 | 3.57 | 4.4 | 5.47 | |||||
| absorbed at°C | 21.8°C | 21.8°C | 21.8°C | |||||||
UPLAND SOILS OF ARID REGION.
| California. | ||||||
|---|---|---|---|---|---|---|
| Placer Co. Auburn. | San Diego Co. National City. | Ventura Co. | Riverside Co. Arlington. | |||
| Number of Sample | 51 | 47 | 182 | 1406 | ||
| Chemical Analysis of Fine Earth. | ||||||
| Insoluble matter | 69.52 | 86.21 | 74.91 | 82.84 | 76.41 | 84.61 |
| Soluble silica | 7.93 | 8.20 | ||||
| Potash (K₂O) | .38 | .48 | .62 | .87 | ||
| Soda (Na₂O) | .07 | .14 | .16 | .29 | ||
| Lime (CaO) | .96 | .36 | .95 | 1.57 | ||
| Magnesia (MgO) | 1.09 | .54 | .96 | 1.33 | ||
| Br. ox. of Manganese (Mn₃O₄) | .39 | .10 | .04 | .04 | ||
| Peroxid of Iron(Fe₂O₃) | 12.42 | 3.69 | 5.07 | 4.20 | ||
| Alumina (Al₂O₃) | 10.97 | 5.12 | 5.94 | 5.30 | ||
| Phosphoric acid (P₂O₅) | .16 | .23 | .13 | .14 | ||
| Sulfuric acid (SO₃) | .01 | .03 | .04 | .01 | ||
| Carbonic acid (CO₂) | ||||||
| Water and organic matter | 5.14 | 2.60 | 2.67 | 1.60 | ||
| Total | 101.10 | 99.50 | 99.41 | 100.05 | ||
| Humus | 1.14 | .56 | 1.06 | .20 | ||
| “ Ash | 1.12 | 1.04 | 1.00 | .64 | ||
| Hygroscopic Moisture | 2.30 | 6.59 | 1.77 | |||
| absorbed at°C | 15 | 15 | 15 | |||