1072 



DRAGON PLANTS 



DRAINAGE 



Dsemonorops Draco. Other kinds of dragon's blood 

 are produced by Dracaena Draco and Ecastophyllum 

 monetaria (now referred to Dalbergia). "Sticks," 

 "reeds," "tears" and "lumps" of dragon's blood are 

 known to commerce. The resin is used in coloring 

 varnishes, dyeing horn in imitation of tortoise shell, 

 and in the composition of tooth-powders and various 

 tinctures. The dragon tree is Dracaena Draco. 



DRAINAGE. Underground or sub-drains serve to 

 relieve the land of free water, which is harmful to most 

 plants if left to stagnate in the surface soil or subsoil. 

 They serve not only to dry the land in early spring, but 

 indirectly to warm it, for if the water is removed the 

 sun's heat warms the soil instead of cooling it by 

 evaporating the surplus water. Tenacious lands 

 devoted to gardening and small-fruits are made more 

 productive, warmer and earlier by sub-drainage. Drains 

 promote nitrification, assist in liberating mineral plant- 

 food and cheapen tillage. They serve not only to 

 remove deleterious stagnant water, but they promote 

 aeration as well, and this hastens beneficial chemical 

 changes in the soil. Drainage promotes the vigor, 

 healthfulness and fruitfulness of plants. Tenacious 

 soils are made more friable by drains, thereby giving 



1348. Old-fashioned drain-tile. 



1347. Diagrams to explain the effect of lowering the water-table by 

 means of under-draining. On the undrained soil, the roots do not pene- 

 trate deep; and when droughts come, the plants suffer. 



easier access to plant roots, while the percolation 

 through the soil of rainwater, which carries some plant- 

 food, is hastened. Rain-water in the spring is warmer 

 than the soil; in midsummer it is cooler than the soil: 

 therefore, percolation of rain-water warms the soil 

 in the spring and cools it in extremely hot weather. 

 Drains serve not only to relieve land of free water, but 

 they impart to it power to hold additional available 

 moisture, which materially benefits plants during 

 droughts. 



Drainage is of two kinds, surface and sub-drainage. 

 On land on which large outlays of money are to be 

 expended, as in horticultural plantations, it is of the 

 utmost importance that the soil be freed to consider- 

 able depths from stagnant water. Trees, many shrubs, 

 and even some garden crops send their roots deeper 

 into the subsoil than most of the cereals, hence they restore the 

 require a greater depth of drained feeding-ground. In land by un- 

 horticulture the planting may often precede the har- der drain- 

 vest by five to ten years, while with many farm crops age, for lack 

 the harvest follows the planting in a few months. If of an outlet 

 the grain-raiser loses one crop, an annual, by planting within rea- 

 on wet land, the loss is not great, but if the orchardist sonable dis- 

 loses fifteen to twenty years of labor by planting on tance, it is 

 undrained lands, before the mistake is discovered, the probable 

 losses are serious. Some lands require little more than that the 

 to be relieved from surplus surface water in early spring. only way to 

 This may be accomplished by forming ridges and open reclaim it 



furrows as far asunder as the rows of trees are to be 

 placed. But it is only rarely that surface drainage 

 fully prevents serious damage from surplus moisture. 

 Surface drainage may be considered a cheap way of 

 temporarily alleviating undesirable conditions. It 

 does not always eradicate them. Fig. 1347 illustrates 

 how sub-drainage lowers the water-table (or the area 

 of standing water), and thereby ameliorates the soil. 



Sub- drainage 

 consists in placing 

 conduits of tile or 

 other material in 

 the ground at 

 depths varying 

 from2^to4feet, 

 and at such dis- 

 tances apart as 

 will serve to relieve the subsoil of deleterious stagnant 

 water. When suitable stones are at hand, they are 

 sometimes used instead of tile for forming drainage 

 conduits. If such use is made of them, the drains should 

 be somewhat deeper than tile drains, since the stones 

 which form the drain occupy nearly a foot of the depth 

 of the ditch and are more likely to become obstructed, 

 especially if placed near the surface, than are tile 

 drains. The throats or openings of stone drains 

 are irregular in size, while those of tile drains are 

 smooth and uniform in size, and are, therefore, 

 most desirable. Years ago, various flat-bottomed 

 tiles (Fig. 1348) were employed, but the style in 

 general use at present is the cylindrical unglazed 

 tile shown in Fig. 1349. They should be hard- 

 burned. Because of the low cost of cement, 

 tiles made of sand and hydraulic cement have 

 recently come into use; they require no burning, 

 are stronger than tiles made of clay and are just 

 as efficient, except in alkali and where frost 

 penetrates very deep. 



In semi-arid districts in which 

 irrigation is practised, if there is 

 a hardpan, nearly or quite im- 

 pervious to water, located within 

 3% to 4^ feet of the surface, 

 the land will in time become 

 sour or charged with injurious 

 alkaline salts, and in many cases 

 ruinously unproductive. Lands 

 of this description are, for the 

 most part, situated west of the 100th 

 meridian. A striking illustration of 

 raising the water-table by too liberal 

 irrigation may be found in a tract of 

 several thousand acres in Tulare 

 County, California, which formerly 

 produced grapes and peaches abund- 

 antly but now yields nothing except a 

 little hardy forage. The water table in 

 this region was once 30 to 40 feet below 

 the surface, but as a result of constant 

 irrigation has risen to within 2 or 3 feet 

 and, in low places, even to the surface, 

 forming a sort of tule swamp. Since 

 the water-table could not be lowered 

 enough to 



1349. Common cylindrical drain-tile; and a scoop 

 for preparing the bed for the tile. 



