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Saving Soil Moisture.
"The Soil." He says: "Since each independent soil grain of a moist soil is more or less completely surrounded by a film of water, it is evident that, other conditions being present, the largest aggregate surface area may retain the most water per cubic foot. Now, a cubic foot of marbles one inch in diameter possesses an aggregate surface of 27.7 square feet, while if the marbles were reduced in diameter to one-thousandth of an inch, then the total area per cubic foot is increased to 37,700 square feet." From this it is evident that the total amount of water capable of being absorbed by a soil which is cloddy and lumpy is very slight in comparison with what it would be were it in a finely divided state; and not only is its absorbing power less, but its power of holding moisture is also greatly reduced.
A large amount of water is lost during the winter and spring months, owing to the surface drainage of melting snows and heavy rainfalls. To prevent this loss, fall plowing may be practiced, and when the subsoil is very hard and compact, the use of the subsoil plow may prove most beneficial. Should the ground break up in clods, then it may be allowed to remain during the winter without harrowing, to more thoroughly subject it to the beneficial action of the elements. But if the soil is in good mechanical condition, and in fruit-land, plants should be growing on it during the winter.
Harrowing to save moisture.-The harrow, besides
pulverizing and fining the soil for the seed-bed, is most efficient in furnishing an earth-mulch. The spring-tooth harrow is in reality a cultivator, and its action is similar to that of the cultivator. When used as an instrument to conserve moisture, the teeth should penetrate to the depth of about three inches, and to produce the best effect the ridges left by it should be leveled off by a smoother, which can now be purchased as an attachment to the harrow. The tillage of orchards by the harrow is now practiced extensively, and nothing short of irrigation will so nearly meet the demands of trees for moisture, particularly upon the heavier soils.
The Acme harrow is a most excellent implement on soils which are comparatively free from stones and rubbish. The plow-like action of its blades serves to pulverize the soil, to spread the mulch evenly, and it leaves a most excellent seed-bed.
The cutaway or disc harrows may be either beneficial or of absolute injury. If the discs are so set that they cover but a portion of the surface with the mulch, they leave a ridge exposed to the action of the wind and sun, and the rate of evaporation is greatly increased. The discs should be set at such an angle that the whole surface shall be stirred or covered. Their chief value lies in their cutting and pulverizing action on clay soils, but as conservers of moisture they are inferior to the Acme or the spring-tooth. Soils which need the disc harrow to pulverize them should generally be gone over again with some shallower tool.
Cultivating to Save Moisture.
The mellower the soil, the lighter should be the work done by the harrow. On most heavy orchard soils, it will be found necessary to use the heavy tools, like the spring-tooth and disc harrows, in the spring, but if the land is properly handled it should be in such condition as to allow the use of a spike-tooth or smoothing harrow during summer. This light summer harrowing should be sufficient to keep down the weeds, and it preserves the soilmulch in most excellent condition. With such a tool and on land in good tilth, a man can harrow ten or more acres a day.
Cultivators and conservation of moisture.-The action of cultivators is not materially different from that of the spring-tooth harrow. The size of the teeth should be regulated by the work to be performed, an implement with many small teeth being preferable to one with a few large teeth, when the object is to conserve moisture. It must be borne in mind that in a dry time the less surface exposed the less will be the evaporation. If a large-toothed implement is used to destroy grass and weeds, then it should be followed by a smoother to reduce the ridges and prevent loss of moisture. Ridge culture is only allowable when the object is to relieve the soil of moisture on bottom lands where the water comes very near the surface, or for some special crops, where a high degree of warmth is required early in the season. In these cases, it may be necessary to throw up ridges to produce the proper degree of warmth for germination, but even then the ridges
should be slight. Nothing could be better calculated to dry out a potato field or a corn field than throwing the ground up in high ridges, leaving a large surface exposed to the action of sun and wind. In fruit plantations which are in a proper state of cultivation, a small-toothed or even spike-toothed cultivator will be found sufficient to maintain the surface mulch.
The roller, in its relation to soil moisture, is an implement whose value depends largely upon local conditions. There is no tool which requires more judgment as to its proper use. On light, loose, sandy or gravelly soils, where every effort must be made to solidify and pack the particles closely together, the roller must be used repeatedly. The difficulty with such soils is that the spaces between the grains are so large that the water is permitted to pass through freely, and is lost by percolation. The capillary openings are so large that there is very feeble rise of the water to take the place of that used by plants and lost by evaporation. The roller lessens the size of these pores in solidifying the soil, and the capillary force the capillary force is then strong enough to draw the water to the surface. If, now, the soil is left in this condition, it has been put in the best possible form for parting with its moisture into the atmosphere, and it will take advantage of the opportunity unless prevented by establishing a surface mulch. In seeding land in a dry time, the soil should be rolled in order to bring sufficient moisture to the seeds to insure germina
Rolling and Smoothing.
tion. When circumstances will permit, the roller should be followed by a smoothing harrow, that the surface mulch may be restored and the moisture stopped before reaching the atmosphere. On clay lands the roller must be used with much caution. If used immediately after grain is sown and a heavy rain follows, there is danger of the soil becoming so compact on the surface that the tender shoots are unable to get through, and the most direct connection is established between the soil moisture and the air. A good method of treatment for clay is to roll before the seed is sown, then harrow and
Fig. 15. A planker or float.
make a good seed bed, and then drill in the grain. After the plants are well up the roller may be used again, which will bring the water to the surface, where the growing plants can make use of it before it passes off by evaporation.
Various kinds of plankers or floats may be used in the place of the roller to smoothen and compact recently tilled lands. A good tool of this kind is shown in Fig. 15. "To make this cheap and easilymade adjunct to good cultivation, take two hardwood planks, 2x8 inches and 7 feet long, and