Red Earths

Red Earths


(Russian, krasnozemy), a type of soil formed under broad-leaved forests in a moist subtropical climate and, partially, in tropical savannas.

Typical features of red earths are a high content of sesqui-oxides (ferric and aluminum oxides) and a very low content of bases and silica. A warm, moist climate promotes intensive processes of rock disintegration, decomposition of aluminosilicates, and loss of calcium and magnesium. Ferric oxides give red earths a bright reddish or orange color. The most typical red earths are found on gentle slopes of 8°-10° to 20°-25°; on steep slopes red earths are weakly developed, shallow, and usually strongly eroded. Strongly marked horizons of washed-out and washed-in material are usually not observed in the profile of these soils. The reaction of red earths is acid or weakly acid (pH of a water extract is 5.0-5.7). They usually have a clayey loam or clayey texture. A distinction is made between the red earths of subtropical forests and those of tropical savannas.

Red earths are widespread in the central and southeastern parts of China, in Vietnam, Japan, eastern Australia, the southeastern United States, Brazil, Uruguay, Africa, the island of Madagascar, southern France, Italy, Spain, and other European countries. In the USSR they are found on the eastern shore of the Black Sea (in the Georgian SSR) and on the southwestern coast of the Caspian Sea (Azerbaijan SSR). Tea, tobacco, grapes, and citrus fruits are among the crops grown on red earths.


References in classic literature ?
Their march this day lay among singular hills and knolls of an indurated red earth, resembling brick, about the bases of which were scattered pumice stones and cinders, the whole bearing traces of the action of fire.
At the distance of about thirty miles from Punta Alta, in a cliff of red earth, I found several fragments of bones, some of large size.
We looked back on it now, the slanting rays of a low sun turning the streams to threads of gold and glowing on the red earth new turned by the plough and the broad tangle of the woodlands.
He crossed to the window and exclaimed, "Lord, how good it is to think of lanes, muddy lanes, with brambles and nettles, you know, and real grass fields, and farmyards with pigs and cows, and men walking beside carts with pitchforks--there's nothing to compare with that here--look at the stony red earth, and the bright blue sea, and the glaring white houses--how tired one gets of it
In front of the first rank, along the river, three men, plastered with bright red earth from head to foot, strutted to and fro restlessly.
The main soil types of the area are broadly identified as Black Earths and Grey Clays (Vertisols) and Red Earths (Alfisols).
The Grey Clay, being inherently well structured and moderately fertile, is more resilient to cropping than the Red Earths of the area.
For soils low in clay, such as the Red Earths, good correlations between aggregation and SOM have been observed.
Soils such as the Red Earths are most susceptible to degradation.
The detrimental impact of cropping on the inherently infertile and weakly structured Red Earth soils is severe and probably occurs soon after the soils are first cultivated.
There were declines in K of 86% on the Red Earth cultivated for 15 years and 66% on the Red Earth cultivated for [is greater than] 40 years.
Site Location WSA >250 [micro]m (%) Decline Red Earth Reference Warialda 43a Cropped (15) 20b 53 Reference Warialda 57a Cropped (40) 25b 56 Grey Clay Reference Warialda 64a, Lucerne (15) 36b 44 Sorghum (40) 39b 39 Reference Croppa Ck 33a Cropped (2) 35a -3 Cropped (43) 22b 33 Reference Moree, 54a Cropped (25) 24b 55 Black Earth Reference Warialda 49a Cropped (40) 14a 71 Reference Warialda 60a Cropped (25) 50a 16 Site Macropore K (mm/h) Decline(%) Red Earth Reference 399a Cropped (15) 55b 86 Reference 144a Cropped (40) 49a 66 Grey Clay Reference 507a Lucerne (15) 231b 54 Sorghum (40) 91b 82 Reference 216a Cropped (2) 219a -5 Cropped (43) 153a 29 Black Earth Reference 192a Cropped (25) 80b 58 Reference 377a Cropped (40) 213b 44 Reference 444a Cropped (25) 194b 56