This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
A thorough distribution of tile drains installed as outlined below, should meet all the requirements commonly imposed from the drainage standpoint upon the construction of these recreation areas. Lines of 4-inch tile should be placed, at intervals of not more than 10 feet. For the most thorough and ideal drainage of these areas, provided the cost is not prohibitive, the construction would be as follows: A neat sub-grade should be made at a depth not exceeding 15 to 18 inches below the proposed finished surface of the recreation area. The necessary lines of tile should be laid in trenches at a depth varying between 2 and 2 1/2 feet below the finished grade, these trenches to be filled with cinders, crushed stone or gravel (Fig. 1355). On this sub-grade, thus completed, the entire recreation area should be filled to a point approximately 6 inches below the proposed finished grade, with cinders, or some equally porous material. On this finished surface, the remaining 6 inches should be filled with a layer of loam free from clay, but composed of a small percentage of sand.
In this way, a firm surface will be obtained which will readily care for any surface and subsoil water.
The secret of a perfect road surface lies (1) in the proper crown of the road, and (2) in the adequate drainage of the subsoil or foundation. The first provision cares for the surface water, and the second provision eliminates any surplus ground-water.
On all private estates on which roads are constructed on heavy clay soils and not on grades greater than 4 per cent, the secret of success depends upon drainage installed in either of the two ways shown in Fig. 1358 or Fig. 1359. Installing a line of drains under the middle of the road is used in soils in which the groundwater level is abnormally high. Such drains should range in depth from 2 to 3 1/2 feet below the finished surface of the road, and the trenches should be filled with a porous material and not with the natural soil. The method of installing drainage under the sides of the road, as shown in Fig. 1358 is used in heavy clay soils, and serves to keep the foundation of the road on well-drained soil. These drains are installed at a depth varying from 2 to 3 feet in trenches filled with cinders or equally porous material.
Fig. 1357. Draining a tennis-court.
Turf pleasure roads, so frequently constructed on private estates, should be thoroughly drained with a line of tile placed under the middle of the road, unless the road is constructed on a heavy foundation of field-stone or gravel which forms a natural drain path for surface-water and soil-water.
In providing drainage along the sides of roads constructed on clay soils through virgin woods, it is sometimes necessary to carry these drainage lines a considerable distance through the woods to suitable outlet points. The joints of all such fines of drainage should be cemented, otherwise the artificial conditions produced by the increased drainage will work serious injury to many large trees growing on either side. In general it is very unsafe to install drainage fines through virgin woods, without this precaution. Roads constructed through such woods would better be drained by laying a line of tile under the middle of the road as shown in Fig. 1359.
A most frequent method of providing drainage for walks is that shown in Fig. 1359. A line of 4-inch tile is laid at a depth varying between 18 inches and 30 inches below the finished grade of the walk and following the middle line of the walk. The trench for the tile is filled with a porous material to a height even with the bottom of the cinders used for the foundation of the walk, or laid as shown in Fig. 1359.
All trees planted in clay soil require drainage. If the pockets in which such trees are planted are not thoroughly drained, the area excavated and re-filled with soil when the trees are planted becomes a pocket for ground-water. This pocket or reservoir collects the water, which, if not carried off by means of drains, will very likely cause the death of the trees. All large trees, especially those which do not grow best with their roots in the water, must be provided with drainage. The common method of drainage is to install a line of 4-inch tile leading from the bottom of the excavated hole to a main line of tile which may have been installed for other drainage purposes, or to the nearest outlet if no such line exists.
It is a frequent practice, especially on large estates, to install open ditches from 50 to 100 feet apart in swamps and in salt marshes, in order to provide a means for draining such areas, and thus preventing the presence of stagnant water, which is conducive to the breeding of mosquitos. These trenches are excavated at depths varying from 2 to 3 1/2 feet. The more frequent the trenches, the shallower they may be made and still provide adequate drainage.
The foregoing article pertains only to the particular phases of drainage especially to be considered in connection with landscape work. For additional information on the general details concerned with drainage, refer to the main article upon drainage, p. 1072.
A. D. Taylor.
Fig. 1360. Detail of drain connections. (See Fig. 1356.)
Drainage is an essential in all retentive soils and is a safeguard even on sandy gravelly subsoils against overwatering. Drainage is likely to be vetoed on the score of expense or on the excuse that the subsoil is gravelly; whereas, there are only gravel stones in hard-pan which holds water. A drain made by filling a pit with stones is frequently inadequate as it fills with water, which backs up into the hole, saturates the soil around the roots and rots them. Rotting of only a part of the roots may injure the tree more than the cutting off of that amount of roots.
The soil in which to plant should be open, porous and aerated. Soil which has been piled up as in grading operations is likely to be sour from the decay of the sod and from the packing by teams and scraper. Muck from ponds which has been piled and mixed with lime for a year may still be sour. Clay soil packed by the water and packing-sticks may remain too compact and not aerated enough, may be too much saturated with water and, therefore, rot the roots. Manure should not be mixed in the soil around the roots on account of the danger of souring and rotting the roots. This rotting is determined by digging down to the roots and finding them of blue-black color with a sour smell. Sometimes this decay has not reached through the bark of the roots and other times it has penetrated the bark and turned the cambium blue-black. Sour soil is likely to be of bluish or greenish color rather than chocolate-brown, and have a sour smell like that underneath a manure heap. The smell is most readily detected by breaking open a lump of soil. In digging into sour soil and soil that is over-satu-rated, the spade makes a peculiar sucking noise as in digging in a bog.
If at the time of examination the soil is already become sour, it is best to take out this sour soil and put in fresh soil covering the roots only 4 inches. The ball of earth in the center will not be so liable to get sour because it has not been disturbed. As brought out by Stringfellow in the "New Horticulture," soil that is dug over will take in water and become saturated; whereas, soil that has not been disturbed will retain air in the soil-spaces even if submerged. The ball of earth is also prevented from becoming saturated by the undisturbed feeding-roots which absorb the moisture.
Watering cannot be by rule, but must depend on examination of both ball of earth in the center and the outer roots. The difficulty will be to keep the ball of earth sufficiently damp on account of the rapid withdrawing of moisture by the roots. The danger will be that the soil outside the ball of earth will take up the water too rapidly, remain saturated several days and rot the roots. Examination is best done by shovel and fork, digging down 1 1/2 feet both in the ball and outside. An easier way is to bore into the soil with an auger. It will usually be found that the central ball of earth is dry and dusty in the summer even if the surface and outer soil is damp. The growth of weeds and grass will indicate the same. A good way to water is to make a basin around the width of the ball of earth, fill it with water 6 inches deep, make crowbar holes into the ball for it to soak in. Many mistakes are made in overwatering- letting the hose run all night or watering every day, thereby rotting the roots.
Mulching is frequently neglected, the tree starving for lack of humus. A close-cut lawn around a newly planted tree may be the ideal of neatness, but it means starvation and thirst for the tree and is the principal cause of slow growth over several years, making new, bare and ugly landscapes. The mulch should extend as wide as the roots and be from 3 to 6 inches deep, of strawy manure, leaves, grass, salt hay or similar organic matter. Too much manure may sour the soil and rot the roots, if it lies heavy and compact and keeps out the air. Light strawy manure is better. If the mulch blows about and is untidy, it may be kept in position by wire netting, earth, or the planting of small shrubs.
Fig. 1361. Setting a newly transplanted large tree.