Pine Bluff daily graphic., 1916-04-09


 ronomlst. University of Arkansas.
 ne organic matter of the soil is that part which has been derived from the decay of plants. When the leaves.
 piaues or grass, stems and roots or plants dla they are at once attached
 by molds and bacteria. The dead Negad1on gradually decomposes or dis lntegrates until the original appear. ance and structure is lost and the material becomes dark colored shapeless mass. called humus.
 Effect of Organic Matter on the Soil.
 Organic matter is beneficial to both sandy and clay soils but in different ways. clay soil without organic matter is too sticky and compact. The organic matter loosens il, permitting me surplus water to drain away and allows air to penetrate to the roots of the crop. On the other hand. sandy soils are too loose and open Water drains away too rapidly and too much air is permitted to enter.
 Effect of Organic Matter on Moisture.
 Sandy soils that are well supplied with organic matters are more reten- tive of moisture than if lacking in that substance The large spaces between tEe sand permit the water to draw away so rapidly that it is soon lost. and the soil dries out. If these spaces are hlled WltlI organic matter the water meets more opposition in it's downward movement consequently it remains for longer time in the zone occupied by the plant roots The fact that organic matter is exceedingly porous adds to it's water holding power. This is shown clearly hy OK periments showing that 100 pounds of straw will take up 200 pounds of Wa ter whereas the same amount of sand will hold only twenty y-tiye. pounds. and 100 pounds of peat soil, which con- sists entirely of humus. will take up from 600 to 1000 pounds of water. Clay soils do not need to have their water holding capacity increased be- cause they are naturally very renten- tive of moisture. such soils are so compact, however, that the roots have difficulty in penetrating deeply into the subsoil. Consequently the crops. are likely to be shallow rooted. The surface soil dries out quickly and the crop suffers. This accounts for the fact that crops often suffer from drought on clay lands sooner than on more sandy soils. If organic matter is t0 al f1o x,,;J root deeper as result of the more open structure and therefore will be able to utilize the moisture stored in the sutsoil and can resist drought. Organic Matter and Plant Food. Organic matter not only improves the physical condition of soils and aids moisture control, but it also con- tains a large amount of nitrogen and other plant feeds in an available form. When the organic matter decays this
 plant food can be used by the sue ceeaing crops
 Soils That Need Organic Matter. The soils of the South are. as a l rule, deficient in organic matter be, cause the high temperature of the summer seasons causes decomposition
 to take place very rapidly. This ten dency is counteracted to certain ex- tent on the creek and river bottom soils by the fact that the large 1 amount of vegetation produced has caused a large supply of organic mat l ter to be stored up. Continuous crop l ping to corn and cotton, however, soon exhausts this original supply So l that even the rich bottom soils be- come depleted after twenty-five or | thirty years. The presence of an abundance of organic matter is
 shown by a black or dark brown color extending several inches below the
 surface. A lack of organic matter is
 shown by light gray or red color.
 Methods of Increasing Organic Mat ter Content of'the Soil.
 The amount of organic matter in l the soil can be increased by applying
 barnyard manure, by turning under all | the corn and cotton stubbs, stubble from grain, sod of meadows and by l turning under green crops. The sub | feet of manures will be treated ln another lesson. The practice of turn ing under green crops is called | green manurng." Where few live
 stock are kept this is an excellent l means or adding organic matter to the
 soil. The crops used for this purpose 1 include cowpeas, soy .beans, clover.
 rye. oats and wheat. The first three
 mentioned, i. e., peas, beans and 1 clover, are legumes and are capable
 oR taking nitrogen from the air and
 uuttinz it into the soil They do this with the help of bacteria liyMg ea