The black cotton soil occurs sometimes in patches, in others extending over plains of hun dreds of square miles.
The red soil of the Madras districts in EOMC places covers extensive plains with a hard-crusted surface, in others it is open, friable, easily worked, and generally fertile. These parts are cropped with cotton and cereals; the grey soils with varagoo, Panicurn Italiorm, and the inferior soils with Penicillaria spicata and Sorghum vulgare.
The soil of that part of the Carnatic which lies nearest to the sea, is loam and sand, sparingly mixed with marine remains, and it has been formed from the debris of the granitic and syenite mountains inland. The rocks of these mountains contain a very small proportion of felspar, which ECCMS to account for the want of the proper admixture of clay, and for the superabundance of iron. It is either a loam mixed with sand and gravel, and strongly impregnated with iron, or, in low and wet places, a stiff red loam mixed with vegetable earth and fine sand, or, on eminences, gravel and sand ; and it is often so much impreg nated with COM111011 Salt tilat it presents a saline efflorescence in dry weather.
Near Madras, it is a heavy sterile salt loam mixed with 81I1C10113 sand ; and along the sea coast, and for some miles inland, sea-shells aro found in a thick black tenacious clay from 10 to 50 feet below the surface.
Between St. Thomas Mount and AreHose, par ticularly on tho higher tracts, the soil is equally poor, though that of the valleys is more fertile, doubtless from the more valuable Farts being washed into theni.
In the valleys along the Eastern Ghats and between the ranges of hills, the soil is chiefly loamy, mixed with sand, and with a considerable proportion of vegetable tnould, which imparts to it its dark shade of brown. The vegetable admix ture and loaminess are owing to the great quantity of water with which it is inundated for a great part of the year for the rice cultivation.
Can/La/ore has black soil, red soil, calcareous soil, and grey-coloured soil, the last being from schistose rocks, gneiss, mica, and hornblende, and is naturally poor. Cumboo, the Penicillaria
spicata, is grown on red and grey soils ; sorghum on black or red soils. Calcareous soil yields ss-ell under moderate but regular rainfall. Black cotton soil has great power of absorbing and fetaining moisture. Mr. Robertson found it capable of holding more than one-third of 'its entire weight of water, and that it has in a very remarkable degree the power of absorbing inoisture from the air. In one night, black soil absorbed per cent., and sandy soil only three-fourths per cent. ' One portion placed in an atmosphere saturated with inoisture, took up 7.99 per cent. of water iv a single night. Its value as a top-dressing merits , trial.
The Neilglierry group of mountains is uniformly covered with a thick stratum of clayey, grey coloured, friable vegetable earth, overlying a , thicker stratum of red earth.
Iti the low valleys and flats at the foot of these hills, and also in the declivities of the hills, the soil is of a black or deep-brown colour, of tenacious consistence when moist, crumbling, into powder and often splitting into masses when dry. It resembles the black soil forming the swampy ground in peat bogs, and also resembles the black soil of the plains of ledia, from which, however, it differs in containing a large quantity of car bonaceous matter and much oxide of iron. Dr. BC117.a exposed it for an hour to an intense heat, from which it lost 25 per cent. of its weight, and changed into an ochry-red powder, but it did not vitrify- as the Dckhan black soil does.
Malabar lands are classed as yielding 20 fold, 15 fold, and 10 fold.
Mysore, for a great part of the level surface of thc table-land, has a red ferruginous arenaceous earth lying over syenite. White kaolin is frequently found between the two. It has a soft greasy feel, and is sometimes mixed with a fine sand. Kaolin of a fine white colour is found in many parts of Mysore.
The Canarese-speaking natives of Mysore dis tinguish eight different soils, viz.:— 1'11ra, black cotton soil, quite free from stones. Kara, the same but stony-.