OKLAHOMA ACADEMY OF SCIENCE 35 



get the necessary plant food. This soil is characterized by its 

 tough, plastic hardpan subsoil about three feet thick below which 

 there is a more, open lower subsoil. 



In 1916 the Oklahoma Experiment Station started some ex- 

 periments on this type of soil with the main object to studying 

 methods of breaking up the sub-soil so that plant roots could pene- 

 trate it and to bring about better moisture and air circulation. 

 The plots selected had been seeded to alfalfa in 1913 and at that 

 time manure was applied at the rate of 12 tons per acre to one-half 

 of the plot,- the other half of the plot having no treatment. In 

 1916 the plots were further divided and lime applied to half of the 

 manured plot and half of the plot that had no treatment, at the 

 rate of 2 1-2 tons of ground limestone per acre. Since that time 

 the plots have received no further treatment. Careful data have been 

 recorded regarding root development, likelihood of the alfalfa plant, 

 and the' crop yield. In studying the root developm.ent two plants 

 were extracted from each of the four plots in 1920, for at this 

 time is was observed that the alfalfa was gradually dying out on 

 the check plot. It was noted that the roots from the plants on plot 

 one failed to penetrate the plastic, clay-hardpan. On plot 2 v/hich 

 received lime in 1916 the roots extended about 6 inches deeper than 

 in the checlc filot. On plot 3 where barnyard manure was applied 

 in 1913 the tap root penetrated the clay hardpan and established 

 a root system in the open, porous lov^^er subsoil. On plot 4 which 

 received manure in 1913 and lime in 1916 the roots extended farther 

 into the open,- porous sub-soil and had the greatest root develop- 

 ment. 



In order to determine v/hether the root development was caused 

 by the stimulating effect of the manure and lim.e on the plant or the 

 :mprovem»ent of the physical condition of the soil by the lime and 

 ijrganic matter, chemical and physical study of the soil was made, 

 and the foUovv'ing are some of the observations : 



Table Shov/ing Maximum Moisture Holding Capacity 1920. 



