tailieunhanh - SUB-SOIL PLOWING

Describe the Mapes plow. Why is the motion in the soil of one and a half inches sufficient? How does the oxidation of the particles of the soil resemble the rusting of cannon balls in a pile? The sub-soil plow is an implement differing in figure from the surface plow. It does not turn a furrow, but merely runs through the subsoil like a mole—loosening and making it finer by lifting, but allowing it to fall back and occupy its former place. It usually follows the surface plow, entering the soil to the depth of from twelve to eighteen. | SUB-SOIL PLOWING Describe the Mapes plow. Why is the motion in the soil of one and a half inches sufficient How does the oxidation of the particles of the soil resemble the rusting of cannon balls in a pile The sub-soil plow is an implement differing in figure from the surface plow. It does not turn a furrow but merely runs through the subsoil like a mole loosening and making it finer by lifting but allowing it to fall back and occupy its former place. It usually follows the surface plow entering the soil to the depth of from twelve to eighteen inches below the bottom of the surface furrow. The best pattern now made the Mapes plow is represented in the following figure. sub-soil plows first made raised the whole soil about eight inches and required very great power in their use often six eight or even ten oxen. The Mapes plow raising the soil but slightly may be worked with much less power and produces equally good results. It may be run to its full depth in most soils by a single yoke of oxen. Of course a motion in the soil of but one and a half inches is very slight but it is sufficient to move each particle from the one next to it which in dry soils is all that is necessary. Whoever has examined a pile of cannon-balls must have observed that at the points where they touch each other there is a little rust. In the soil the same is often the case. Where the particles touch each other there is such a chemical change produced as renders them fit for the use of plants. While these particles remain in their first position the changed portions are out of the reach of roots but if by the aid of the sub-soil plow their position is altered these parts are exposed for the uses of plants. If we hold in the hand a ball of dry clay and press it hard enough to produce the least motion among its particles the whole mass becomes pulverized. On the same principle the sub-soil plow renders the compact lower soil sufficiently fine for the requirements of fertility. Pg 234 Why are .