north of the southern boundary of Tennessee. Its climatic range is similar to that of cotton, being between 45° N. to 38° S. Lat. in the Eastern, and from 36° N. to 38° S. Lat. in the Western Hemisphere. Certain varieties of upland rice are said to be adapted to a somewhat wider climatic range. While upland rice may be raised by methods not dissimilar to that of oat culture, it is neither so productive nor of so good a quality as when raised by irrigation, the method most commonly practiced.

07. Soil. The principal considerations concerning soil for rice are the ability to irrigate it, to drain it promptly, and to become solid with sufficient rapidity after the water has been removed for the passage of animals and machinery. Different degrees of fertility, however, are recognized, and soils of a clay nature have been found better than those of a sandy or peaty character; although here, as with other crops, a loamy soil with a fair degree of organic matter is desirable. The principal areas in the United States devoted to rice are: (1) the delta land and inland marshes of the South Atlantic States, (2) the alluvial lands along the Mississippi River, and (3) the prairie soil of southwestern Louisiana and southeastern Texas. The practices prevailing in the third area are radically different, both because the topography makes possible larger fields and because the solid subsoil allows the use of self-binding harvesters for gathering the crop. Upland rice may be grown upon any soil that will grow maize or cotton, and the method of culture is not materially different from that of oats or other spring sown grain.

508. Rotation.-A rotation of crops is seldom practiced on the rice plantation, although it is recognized that a rotation would increase the yield of rice per acre; but it would reduce the area grown. One very important reason for a rotation of crops is to free the land of noxious weeds; and planters are being forced to adopt a rotation for this purpose, which consists

WAGON ROAD. OUTSIDE LEVEE.

of interjecting some other crop about once in four years, preferably a cultivated crop, such as maize, or merely permitting the plantation to grow up to dry land weeds.

509. Fertilizers.-Many kinds of fertilizing material are commonly employed in oriental countries; in the United States

Plat of rice field in Raywood plantation showing method of Irrigation in southwestern Louisiana and southeastern Texas. The different tracts are on different levels. Water enters at measuring flume, floods first tract, passes over field levee, floods second tract, and so on until the whole field is flooded. Water is removed through drainage ditch by opening field levees. On this plantation the water in the main canal shown in illustration has been raised a total of sixty-five feet by means of three pumping stations. At the initial station the canal is 150 feet wide. (After Bond.)

the land is seldom manured for rice. The irrigation of the land presents problems concerning nitrification and supply of fertilizing constituents from the water that have not been fully

worked out. Usually the water has an abundance of potash, a partial supply of nitrogen for the crop requirement, and scarcely any phosphoric acid. The Louisiana Station suggests the possibility of applying nitrogen and phosphorus in high grade commercial fertilizers in small quantities continuously to the water at the flood gates. Stable manure can be used judiciously upon places where surface soil has been removed in leveling

Plat showing method of irrigating rice plantation in South Atlantic States. Heavy black lines represent levees about six feet high, thirty-five feet wide at bottom and twelve feet wide at top. Main canal reaches from river to creek between two levees. Double lines around each tract represent marginal canals or face ditches about three feet wide and deep, and single lines represent field ditches about fifty feet apart. Water enters and leaves each tract through the same flume by means of a box, called a trunk, so arranged that it can be set to allow the water to enter at high tide or can be set to allow water to leave at low tide. (After Keeney.)

the land; but heavy applications are to be avoided upon good soil, lest it cause the rice to lodge. If the straw and hulls are returned to the land the fertilizing ingredients removed are comparatively small. Here, as elsewhere, the economy of fertilizers is a local question, and no specific rules can be given. (117)

510. Laying Out the Plantation.-In preparing a plantation for rice culture, the area must be laid off into fields and a levee

or dike thrown up around them. On at least one side of each field there must run a canal or sub-canal. These fields vary in shape and size according to the topography of the land and the ability to bring water to it. Usually the fields range in size from ten to forty acres. These fields are now subdivided into smaller areas, in order to get the water over the whole area with some uniformity. It is at this point that the system followed in the South Atlantic States differs radically from that of the South Central States. In the former the fields are subdivided by ditches placed parallel, usually about fifty feet apart, through which the water is conveyed to and from the land. In the South Central States the fields are divided into sub-fields or cuts, this being done by throwing up field or cut levees along the contour lines twelve to eighteen inches high. To flood the field, water is turned into the highest cut and conveyed from there to the next highest cut, and so on until the field has all been flooded. A drainage ditch at the long part of the field removes the water. The main features of the two systems are shown in the illustrations on pages 362 and 363.

It is important that each of the smallest units of land be as level as possible, so that the water can be kept at as uniform depth as may be over the whole area, since uniformity of depth of water is a prime factor in the growth and maturity of the crop. To obtain the best result, there should not be a variation of more than six inches in the depth of water.

511. Water Supply. In the South Atlantic States the lands chiefly used for rice culture are the deltas near tidewater. Land is selected so that it may be flooded from the river at high tide and drained at low tide; and is sufficiently remote from the sea to be free from salt water. Rice may be grown in slightly brackish water, but salt water is disastrous. Usually the land is not less than fifteen nor more than thirty miles from the sea. A tide of four feet is sufficient and less is sometimes used. Where properly located, water in this region is ample. Along

the Mississippi River the water was formerly supplied from the river by putting a pipe through the levee, the land being highest next the river and the drainage being away from the stream. The water is now conveyed over the levee by means of a siphon, the former method being prohibited by law because the majority of disastrous breaks in the levees was attributed to them. In southwestern Louisiana and southeastern Texas not only are streams used for irrigation but advantage is taken of a stratum of water that underlies this territory at a depth of 125 to 200 feet. When tapped, this water rises near the surface, sometimes within twenty feet, and in a few instances flowing wells have been obtained. Whatever the source of water, it is pumped to raise it to the proper level. The individual planter may have his own pumping outfit or water may be furnished an extensive area from a single system, and the planter is charged a certain percentage (usually one-fifth) of the rice raised for water supplied, or a certain number of pounds of rough rice (usually two barrels, or 324 pounds).

Water for irrigation purposes should be uniform in temperature, not too cold, free from noxious weed seeds and injurious salts. 512. Amount of Water Required.-The amount of water required will vary with many conditions, including evaporation, seepage, drainage and the rainfall. Where abundant and obtained by gravity, larger quantities are likely to be used than where it is pumped. The Louisiana Station says that in that State each acre of rice is assumed to receive the equivalent of one-half inch of water daily during ninety days; this is forty-five inches. Deducting twenty inches for rainfall leaves twenty-five inches to be supplied by irrigation.1

The Office of Experiment Stations has measured the water used at two plantations where water is obtained by pumping, with the following results:2

1 La. Bul. 77, p. 382.

O. E S. Bul. 113, pp. 22-28.