EXPERIMENT STATION REPORTS. 237 



"In the experiment already under way when the problem was turned 

 over to me in the spring of 1918 a series of composts consisting of various 

 proportions of peat and manure had been made, viz., 50-50; 75-25; and 

 90-10 peat and manure respectively including a pile each of peat alone and 

 manure alone. These were used on an experimental plot consisting of 

 nearly pure sand and sowed with Canada field peas. It was soon noted 

 that the plots containing pure (100 per cent) peat first, then in succession 

 the mixtures containing the lesser percentages of peat showed the most 

 rapid growth, in marked contrast not only to the check (sand) as would 

 be expected but to the manure alone. This phenomenon is attributa- 

 ble to nothing else but to the water holding capacity of the peat. 

 Later experiments have shown this same sequence of events on another 

 type of soil with another crop. 



"Bacteriological studies were made of the sandy soil alone and with 

 the different additions during the growing period. 



"The peas were picked and. used in a canning experiment. Studies of 

 the soil solution from these piles showed a larger percentage of nitrates 

 per unit amount of manure in the pile containing the least amount of 

 manure. 



"The concrete compost pit which was described in the 1918 Annual 

 Report was completed in July, 1918, and filled with a mixture of peat, 

 manure, and rock phosphate with the addition of sufficient liquid manure 

 to insure anaerobic conditions as well as to serve as an inoculum. 

 Bacteriological and chemical analyses have been made from samples taken 

 bi-weekly as a rule except through the winter months. 



"Bacteriological analyses show that large numbers both of aerobic 

 and anaerobic cellulose decomposing organisms were present and are on 

 the increase. In the aerobic class, which includes not only bacteria but 

 actinomycetes and molds the average number now (June 1919) ap- 

 proximates 3,000,000 per gram of oven-dry mixtures. The anaerobic 

 class also 'approaches this figure, having increased to this amount from 

 an average of about 5,000 per gram of oven-dry mixture. Thus it would 

 seem that the cellulose portion of the peat must be undergoing decom- 

 position and that the conditions in this pit are not inimical to organ- 

 isms of this class. 



"Work with the organisms concerned in the dissolution of rock phos- 

 phate shows their presence quite frequently in considerable numbers, 

 but at present the known cultural methods are faulty. This is one gen- 

 eral drawback to rapid progress along certain lines of soil bacteriologi- 

 cal work. Chemical analyses of the material from the pit show that there 

 has been roughly an increase of about 8 per cent in the citrate-soluble 

 phosporus in a period of nine months. There has been a decrease in 

 total phosphorus of about 20 per cent of the original amount present. 

 This can be accounted for by the presence of large amounts of citrate- 

 soluble phosphorus in the drainage water. If this also is taken into con- 

 sideration considerably more than 8 per cent of the citrate-soluble phos- 

 pliorus has been liberated in the past nine months. 



"As the presence and number of Azotobacter species in soil can be 

 determined quite readily by the mannit agar plate method it has been 

 possible to enumerate them in this compost with considerable accuracy 

 Azotobacter have been found not only in the surface samples but in the 

 bottom samples, which have existed for over 9 months under decidedly 

 anaerobic conditions. 



