Burbank: Methods and Discoveries, vol. 10: 245-245 (1914)

A PRACTICAL DRAINAGE SYSTEM

Many hundreds of persons visiting my experiment grounds at Santa Rosa each season have marvelled at the exceedingly varied and prolific crops raised—exclaiming, "What a delightful soil you have!"

Their surprise grows when they are assured that this productive land was originally almost valueless for growing plants. It was made fruitful by artificial drainage and irrigation. The application of the simplest principles of regulation of water supply resulted in transforming a relatively sterile soil into one of the most fertile areas of the earth's surface. The method in which this was accomplished may be outlined as offering a model that may be followed to advantage in draining similar land anywhere.

Probably half the low-lying soils in the United States could be made more productive by drainage. Even if the soil of your lawns and gardens is fair productive, you may advantageously consider advisability of introducing such a system of drainage as that which we have employed at Santa Rosa with such striking results.

The soil consisted of what is called adobe, a black clay-like soil, said to be of volcanic origin, and this particular piece cracked so during the latter part of the dry season, that it was considered unsafe to pasture stock on it, as it endangered the legs of the animals, the cracks being often several inches in width and apparently bottomless. No crop had been grown here for years; and home lots a mile or more out sold for about the price I paid for the four acres.

Of course there is nothing novel about the statement that the drainage of land is important. The matter has been more or less understood since the earliest periods. Yet a very large part of the land of the United States that is given over to lawns and gardens is left to depend entirely on natural drainage, and fails to produce anything like the crops that might be grown on it, if a more rational provision had been made for adjusting the water supply.

In California the value of drainage has been shown in the results obtained even with wheat fields drained and those not drained. Only one or two ditches across a field have made it possible to produce two or three times as large a crop as grown in the same field before the ditches made.

In a certain oat field in Wisconsin, the yield per acre was doubled by drainage. The yield before drainage was only sixteen bushels, but after drainage it increased to 32.3 bushels per acre.

There are at least two bad effects to be expected from an oversupply of water. They are:

  1. An oversupply makes certain areas so soft that they cannot be cultivated at all or at least not until late in the spring.
  2. Air, which is essential to plant growth, cannot enter the soil supplied with a superabundance of water.

Air is as necessary to the roots of plants as water and it is upon this principle that all systems of cultivation and drainage are based.

The complicated chemical changes in growth of the plant cannot take place unless there is sufficient of both air and water. Roots cannot exist where there is a superabundance of water in the soil.

There are several systems of drainage which will not be discussed here. I consider underdrainage with common drain tile the best system for ordinary conditions, and it is with this system that I have had most experience. The discussion is given mostly from the viewpoint of results on my own grounds.

Small, well-burned drain tile was used on my Santa Rosa ground carefully laid with a slope of 1 foot to 40 feet and it has proven eminently satisfactory in every respect for twenty years. The soil is a heavy adobe and was almost worthless before it was drained.

The good results of the drainage were scarcely apparent the first year, but the benefits were multiplied each year until now the soil is easily cultivated and bears enormous crops while before draining no crop could be raised.

This system consists of one main line of 4-inch tile with laterals of two-inch tile every 40 feet. The laterals gather the surplus water quickly after a heavy rain and the main tile carries it to a small stream near by.

The laterals do not need such a large capacity as most people think. It must be remembered that they work both day and night, and Sundays as well as week days and a very small tile will carry a great amount of water in the course of twenty-four hours.

It is a good plan to have the tiles flushed now and then, and if they are not too large they will sometimes be flushed during heavy rains when they are filled to capacity. This flushing serves to keep them clean and the flushing produced naturally when small tiles are used is sufficient reason for recommending the smaller sizes rather than larger ones which are more expensive and generally less efficient.

The general impression is that cracks should be left, and sand put in the cracks. The real way is to surround the joints with clay; then they are permanent. The worst thing to do is to put sand or gravel or straw about the cracks. A tile four feet deep will drain twice as wide an area as a tile two feet deep. About four feet is the proper depth.

The strength of the entire system depends upon the weakest section. Therefore it is necessary in laying the tile to examine carefully each piece, and to see that they are well burned, but not sufficiently to make them impervious. The system must be laid upon the proper grade, for if the line sags, sediment will collect and retard the flow of water.

It is best to make a silt basin at some point where the branching tiles unite. This is formed by digging down a foot or two, and bricking or cementing up a barrel-like receptacle, the entrance pipe from the main system being a little lower than the exit pipe, so that the silt settles.

In the twenty years since the tile system was laid at Santa Rosa, the tile itself has never been exposed, or in any way touched or examined. It continues to perform its function perfectly.

Drainage is really a science in itself, and there is not enough space here to give a full discussion of it. There are a number of good books on the subject, however, and the names of these will be found in the chapter on reference literature.

Before the system is installed, some complete treatise on drainage should be thoroughly studied.

In some cases it is possible to secure the aid of a person who has had experience in laying drain tiles, and where this is possible it is the best plan.