The Brinkley argus., 1916-04-07
SOILS AND SOIL FERTILITY
No. 5. Organic Matter.
By De F. Hungerford, Assistant Ag- ronomist, University of Arkansas.

By De F. Hungerford, Assistant Ag-
 ronomist, University of Arkansas.
 The organic matter Of the soil Is that part which has been derived from the decay of plants. When the leaves, blades of grass, stems and roots Of plants die they are at once attached by molds and bacteria. The dead vegation gradually decomposes or dis integrates 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 Son. Organic matter is beneficial to both sandy and clay soils, but in different ways. A clay soil without organic matter Is too sticky and compact. The organic matter loosens it, permitting the 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 we'll supplied with organic matters are more reten- tive of moisture than if lacking in that substance. The large spaces between the sand permit the water to draw away SO rapidly that 1t Is soon lost, and the soil dries out If these spaces are filled with 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 its water holding power. This is shown clearly by ex- 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-five 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 | supplied to clay soils the crop will | root deeper as result of the more | able to utilize the moisture stored in the suhsoil 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 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 ceeding crops.
 Soils That Need Organic Matter.
 The soils of the South are, as a rule, deficient in organic matter be cause the high temperature of the summer seasons causes decomposition to take place very rapidly. This ten dancy Is enumerated to a certain ex tent on the creek and river bottom soils by the fact that the large amount of vegetation produced has caused large supply of organic mat ter to be stored up. Continuous crop soon exhausts this original supply s, that even the rich bottom soils be come depleted after twenty-five ol thirty years. The presence of ar abundance of organic matter ii shown by black or dark brown colol extending several inches below the surface. A lack of organic matter i! shown by a light gray or red color.
 Methods of Increasing Organic Mat
 ter Content of the Soil.
 The amount of organic matter il the soil can be increased by applying barnyard manmre, by turning under al the corn and cotton stubbs, stubbl' from grain, sod of meadows and b. turning under green crops The sub ject of manMres will be treated il another lesson. The practice of turn ing under green crops is callet "green manurmg." Where few live stock are kept this is an excellen means or adding organic matter to tn
 soil The crops used for this purpos
 include cowpeas, soy beans, clover rye, oats and wheat. The first thre
 mentioned, i. C., peas, beans sn
 clover, are legumes and are capabI
 of taking nitrogen from the air an
 putting it into the soil. They do thi with the help of bacteria living O
 their roots Al