The Country Gentleman 81(42): 1827 (October 14, 1916)

The Sun and the Soil
E. R. Jones

A WET soil is a cold soil. It weakens seeds and sickens plants. The way to warm a soil is to drain it. A drain three feet deep never made a soil too dry. The force of capillarity is always present to keep a film of water round the soil grains. This force fixes the limit up to which drainage is necessary, and beyond which it is impossible.

In a drained soil the heat of the sun is directed to the soil and not to the unnecessary water it may contain. The sun is thus given a chance to make its work count. Starting at thirty-two degrees the sun has to raise the soil temperature as nearly to the optimum as possible. Eighty degrees is the best reached at Lincoln, Nebraska. Crops have learned to do fairly well at sixty degrees.

The moment soils thaw out in spring each cubic foot of saturated clay weighs about 100 pounds—seventy pounds of soil and thirty pounds of water at thirty-two degrees Fahrenheit. Fifteen pounds of water to a cubic foot is plenty.

A cubic foot of wet peat weighs about seventy-five pounds, of which fifty pounds is water. Saturated peat is in worse shape than saturated clay.

It takes five times as much heat to warm a pound of water as it does to warm a pound of soil. For every unit of heat required to warm the twenty-five pounds of peat one degree, ten units are required to warm the fifty pounds of water one degree. Only one sunbeam in eleven is used to warm the soil. The other ten spend themselves on the water. Do you wonder why a wet soil warms up slowly? Does not a teakettle boil more quickly when it is only half full of water?

But somebody says: "Let the water evaporate." This is a desperate remedy. Evaporation requires energy. It is the heat applied at the bottom of a teakettle that makes the steam shoot out at the top. It takes just as much heat to evaporate a pound of water slowly as it does to drive it off rapidly as steam.

The cheapest energy available to the soil is the sunbeam.

The sunbeams that are required to evaporate a single pound—about one pint—of water at thirty-two degrees would raise the temperature of about thirty-eight pounds of water or 190 pounds of soil—nearly three cubic feet—from thirty-two to sixty-two degrees. You cannot afford to let the water evaporate at this tremendous expense. It is better to let gravity draw off the excess water without expending any sunbeams at all. Let the sunbeams be consumed in warming only the soil and the necessary water.

The raindrops falling in the early spring are usually warmer than the soil. If the soil is saturated with water these raindrops run off the land as they would run off a duck's back, carrying their heat with them. The raindrops enter a drained soil, and their heat enters with them. This helps the sunbeams warm the soil.

Another thing: Warm air circulates in a drained soil. It acts like a hot-air furnace. Warm air enters the soil and leaves some of its heat there.

A warm soil allows the soil bacteria to work—fixing nitrogen, decomposing vegetable matter and producing soluble plant food. There is neither heat nor air enough in a wet soil to let the decomposing bacteria work.

Seeds germinate rapidly in a warm soil. Moreover, you can get on a well-drained soil earlier in the spring with a seeder or planter than you can get on a wet soil. The rows of corn show green between lines of drain tile before you can plant on the undrained land at all.

Some weeds thrive at low temperatures. Corn and cultivated crops generally do not. Weeds get the start of the corn during a cold spring.

Warm soils prevent frosts in the late spring and early fall. A warm soil has a breath of warm air escaping from it at night. This protects the tender plants in the absence of the sunbeams. The next morning the sunbeams warm the soil again, thus making the soil a reservoir of heat for use on a cold night. But you must give the sunbeams a chance.