Underdrainage.--There are great swamps, and small ones, whose water should be carried off by open ditches. Our present interest is in the wet fields of the farm,--the cold, wet soil of an entire field, the swale lying between areas of well-drained land, the side of a field kept wet by seepage from higher land,--and here the right solution of the troubling problem lies in underdrainage. An excess of water in the soil robs the land-owner of chance of profit. It excludes the air, sealing up the plant-food so that crops cannot be secured. It keeps the ground cold. It destroys the good physical condition of the soil that may have been secured by much tillage, causing the soil particles to pack together. It compels plant-roots to form at the surface of the ground. It delays seeding and cultivation. An excess of water is more disheartening than absolute soil poverty. The remedy is only in its removal. The level of dead water in the soil must be below the surface--three feet, two and one half feet, four feet,--some reasonable distance that will make possible a friable, aerated, warm, friendly feeding-ground for plant-roots. Only under drainage can do this. Counting the Cost.--Thorough underdrainage is costly, but it is less so than the farming of fields whose productiveness is seriously limited by an excess of water. The work means an added investment. Estimates of cost can be made with fair accuracy, and estimates of resulting profit can be made without any assurance of accuracy. The farmer with some wet land does well to gain experimental knowledge, and base future work upon such experience. He knows that he cannot afford to cultivate wet land, and the problem before him is to leave it to produce what grass it can produce, sell it, or find profit in drainage. He has the experience of others that investment in drainage is more satisfactory than most other investments, if land has any natural fertility. He has assurance that debt incurred for drainage is the safest kind of debt an owner of wet land can incur. He has a right to expect profit from the undertaking, and he can begin the work in a small way, if an outlet is at hand, and learn what return may be expected from further investment. Almost without fail will he become an earnest advocate of underdrainage. [Illustration: Drain tile.] Where Returns are Largest.--The total area of land needing drainage is immense. Swamps form only a small part of this area. Yields of much old farm land are limited by the excess of water during portions of the year. As land becomes older, the area needing drainage increases. The owner of wet land does well to gain his first experience in a field where a swale or other wet strip not only fails to produce a full crop, but limits the yield of the remainder of the field by delaying planting and cultivation. This double profit often is sufficient to repay cost in a single year.