INFLUENCE OF LIME UPON SOIL FERTILITY.
Assuming as substantially correct the numerical data given above in respect to the three leading ingredients of plant-food—phosphoric acid, potash and nitrogen,—the dominant role of lime in soil fertility, already mentioned, requires some farther illustration and discussion.
“A Lime Country is a Rich Country.”—The instant change of vegetation when we pass from a non-calcareous region to one having calcareous soils, has already been alluded to. ([See this chapter, p. 354)]. But it is not necessary to be a botanist to see the change in the prosperity of the farming population as one enters a lime district. The single log-cabin with, probably, a wooden barrel terminating the mud-plastered chimney, is replaced, first by double log-houses, then by frame, and farther on by brick buildings, with the other unmistakable evidences of prosperity. Thus this is seen in passing from the mountain region of Kentucky into the “blue-grass” country, which is throughout underlaid by calcareous formations; and thus, likewise, in crossing the strike of the formations of Alabama, Mississippi and Louisiana, or any other region where underlying calcareous formations have contributed to the formation of the soils, as compared with some adjacent district where this is not the case. The calcareous loess areas bordering on the Mississippi river and some of its chief tributaries, are conspicuous cases in point, as are also the prairies of Illinois and Indiana.
Effects of High Lime-content in Soils.—The table below illustrates the fact that in the presence of high lime-percentages, relatively low percentages of phosphoric acid and potash may nevertheless prove adequate; while the same, or even higher amounts, in the absence of satisfactory lime-percentages prove insufficient for good production.[123]
SOILS SHOWING LOW PHOSPHORIC ACID
PERCENTAGE.
| High Lime. | ||||||
|---|---|---|---|---|---|---|
| Mississippi | Louisiana | California | ||||
| Kemper County | Vernon County | Yuba County | Amador County | |||
| Number of Sample. | 139 | 171 | 499 | 1113 | ||
| CHEMICAL ANALYSIS OF FINE EARTH. | (Slate Soil) | |||||
| Insoluble matter | 67.08 | 53.19 | 74.29 | 78.79 | 49.96 | 64.92 |
| Soluble silica | 21.10 | 3.80 | 14.96 | |||
| Potash (K₂O) | .70 | .33 | .25 | 1.48 | ||
| Soda (Na₂O) | .14 | .06 | .04 | .43 | ||
| Lime (CaO) | 1.37 | 1.40 | 1.02 | .60 | ||
| Magnesia (MgO) | 1.00 | .74 | .40 | 2.21 | ||
| Br. ox. of Manganese (Mn₃O₄) | .25 | .15 | .02 | .05 | ||
| Peroxid of Iron (Fe₂O₃) | 6.75 | 4.52 | 5.81 | 11.52 | ||
| Alumina (Al₂O₃) | 13.07 | 11.36 | 6.28 | 12.31 | ||
| Phosphoric acid (P₂O₅) | .03 | .05 | .04 | .05 | ||
| Sulfuric acid (SO₃) | .08 | .12 | .02 | .02 | ||
| Carbonic acid (CO₂) | ||||||
| Water and organic matter | 9.45 | 7.27 | 3.64 | 6.63 | ||
| Total | 99.91 | 100.29 | 100.19 | 100.22 | ||
| Hygroscopic Moisture | 11.45 | 18.11 | 4.80 | 5.74 | ||
| absorbed at°C | 8.0 | 25.5 | 15.0 | 15.0 | ||
| Low Lime. | |||||||
|---|---|---|---|---|---|---|---|
| Mississippi | California | ||||||
| Chickasaw County | Carroll County | Shasta County | Humboldt County | ||||
| Number of Sample. | 164 | 48 | 559 | 207 | |||
| CHEMICAL ANALYSIS OF FINE EARTH. | |||||||
| Insoluble matter | 93.62 | 94.98 | 89.39 | 76.27 | 80.38 | 65.35 | 72.24 |
| Soluble silica | 1.36 | 4.10 | 6.90 | ||||
| Potash (K₂O) | .09 | .19 | .50 | 1.13 | |||
| Soda (Na₂O) | .07 | .08 | .04 | .28 | |||
| Lime (CaO) | .07 | .08 | .10 | .11 | |||
| Magnesia (MgO) | .13 | .07 | .40 | 3.33 | |||
| Br. ox. of Manganese (Mn₃O₄) | .02 | .12 | .01 | .12 | |||
| Peroxid of Iron (Fe₂O₃) | 1.09 | 1.21 | 6.67 | 6.99 | |||
| Alumina (Al₂O₃) | 1.47 | 4.37 | 8.48 | 10.24 | |||
| Phosphoric acid (P₂O₅) | .03 | .05 | .04 | .17 | |||
| Sulfuric acid (SO₃) | .01 | .05 | .01 | .02 | |||
| Carbonic acid (CO₂) | |||||||
| Water and organic matter | 2.00 | 4.09 | 3.97 | 5.63 | |||
| Total | 99.94 | 99.70 | 100.62 | 100.24 | |||
| Hygroscopic Moisture | 1.80 | 4.66 | 5.05 | 7.87 | |||
| absorbed at°C | 11.0 | 11.0 | 17.0 | 13.0 | |||
Nos. 139 and 171 are heavy black prairie soils of high productive capacity, whose production had, at the time of sampling, lasted almost undiminished for over twenty years. Nearly the same is true of the two California soils, Nos. 499 and 1113; which, however, are ferruginous loams of only moderate clay-content. In all, the percentage of phosphoric acid shown by the analysis is at or below the recognized limit of deficiency, while the lime-content of all is as high as is required for the welfare of any soil, however constituted. The potash-percentage also is low in all except the “red foothill soil,” No. 1113.
Passing to the soils of low lime-content, we find the two Mississippi soils, poor in both potash, lime and phosphoric acid, so low in production as to be wholly unprofitable in cultivation without previous fertilization; No. 559, from California, produced two fair crops of barley and then no more. No. 207, is the soil of Eel river bottom, California; profusely productive at first, by virtue of its high content of both potash and phosphoric acid; but “giving out” under a few years’ culture of clover or alfalfa (which draw heavily upon lime), and quickly restored to productiveness under the influence of dressings of quicklime. In this case the soil had become acid, a condition which always militates against the success of culture plants, and more especially against those of the leguminous relationship.
What are Adequate Lime Percentages?—We have in the presence or absence of the natural vegetation peculiar to calcareous soils (“calciphile”) an excellent index of the presence or absence of such amounts of lime carbonate as fulfil the conditions of its beneficial effects. Lists of such plants for the United States are given farther on; they agree almost throughout with such plants as are everywhere recognized by American farmers as indicating productive soils.