202 EEPOET OF OFFICE OF EXPERIMENT STATIONS. 



Independent of the foregoing project, work was conducted op soil 

 biology in its relation to humus formation. The improvement of the 

 laboratory equipment for this work included the installation of a 

 specially designed autoclave, consisting of a cylinder 28 inches in 

 diameter and 36 inches long, connected with a steam boiler for the 

 purpose of sterilizing soil. In addition, a complete equipment was 

 secured for the determination of the various forms of nitrogen in 

 the soil, and apparatus was designed for keeping the soil sterile 

 while air and water are supplied freely, and for the cultivation of 

 higher plants without the presence of bacteria, A special study was 

 made of Pseudomonas radicicola of the soy bean in its relation to 

 the transformation of the nitrogen in the soil and the bacterial con- 

 tent of soils and its capacity for nitrification, denitrification, and 

 other activities were determined. Much of the work done on this 

 project the past year was of a preliminary nature. 



In the study of clover anthracnose, sjDecial attention was given to 

 the physiology of disease resistance. During the past year about 200 

 acres of clover were grown in the State from immune seed and in 

 every case the clover was free from anthracnose. The distribution 

 of the disease-resistant strains was continued. 



Studies on the life history and habits of the cattle tick were pur- 

 sued as in the previous year, and the degrees of temperature and 

 humidity limiting the tick area were determined. The time required 

 for eggs to hatch and for seed ticks to die was worked out for three 

 stations, Knoxville, Dallas, and Baton Rouge. This was found to be 

 all a matter of cumulative effective temperature, and from the data 

 obtained it is possible to establish the time limits of pasturing cattle 

 without exposing them to tick infection. 



The Hatch fund work of the station in agronomy included the 

 development of a double system of cropping, a study of temperature 

 and rainfall conditions with reference to crop production, experi- 

 ments on subsoiling and deep plowing, a determination of the relative 

 fertilizing values of ground phosphate rock and other phosphates, 

 and a study of the lime requirements of Tennessee soils. Barley used 

 in the double cropping system and fed to steers was found to be one 

 of the best crops for building up the land. The value of deep culture 

 became evident during the past dry year. Selection Avork with 

 cereals was continued and the station now has its own strains of 

 barley, oats, and tall oat grass. The results of experiments in a 

 rotation of cowpeas and wheat and the utilization of various phos- 

 phates were published in Bulletin 90 of the station during the year. 

 Kock phosphate gave about as good results where no lime was used 

 on some soils, but on others inferior results were secured. Decidedly 

 the best results were obtained from acid phosphate with lime. 



