262 



Journal of Agricultural Research 



Vol. VI. No. 7 



obtained. Sorghum made slow growth; leaves yellowish for first seven or eight 

 weeks. 



3. Agricultural Experiment Station, Manhattan, Kans. Plots grown on "creek 

 bottom land," broken from native sod in 1913; drainage poor. Planted on June 15; 

 appeared aboveground on June 22; cultivated twice. Sorghum 30 days slower in 

 maturing than usual, owing to excessive rains. 



4. Belle Fourche Experiment Farm, Newell, S. Dak. Dry farming. Planted on 

 June 10; appeared aboveground on June 26; cultivated on July 22 and August 7; 

 harvested on October 12. Season cold and wet; rainfall far above normal. 



5. Belle Fourche Experiment Farm, Newell, S. Dak. Irrigation farming. Planted 

 on May 31; appeared aboveground on June 26; cultivated on July 23 and August 10; 

 irrigated on August 17; harvested on September 16, when plants were just headed out. 



From the time when the plants were from 20 to 30 cm. in height, sam- 

 ples were taken every 10 days. They were usually cut between 9 and 

 12 a. m., although it has been found that the time of day makes no 

 difference in the amount of hydrocyanic acid present. Plants were 

 selected which represented the average of the plot on that date. For the 

 first sample the whole plant was cut into i-inch lengths and packed into 

 a 600 c. c. friction-top tin can with 20 c. c. of 3 per cent alcoholic sodium 

 hydrate and 2 c. c. chloroform for preservatives and sent to the Minne- 

 sota laboratory for analysis. For the other samples the leaves were cut 

 off where they join the sheath, and the leaves and stalks were packed 

 and analyzed separately. The weight of leaves and of stalks in the 

 total sample cut was recorded. From the fourth sample on, cans of 

 1,600 c. c. capacity were used. An alkaline preservative was used so as 

 to prevent any possible loss of hydrocyanic acid set free by enzymic 

 activity. Alcohol instead of water was used as a solvent for the alkali, 

 because it penetrates the plant tissues more readily. The chloroform 

 prevented any fermentative changes. In the case of the South Dakota, 

 Kansas, and Utah samples, from two to five days elapsed from the time 

 the samples were cut till they were analyzed. In the case of the Minne- 

 sota samples, the fresh material was analyzed. In order to test the 

 efficiency of the preservative, several samples from the Minnesota plots, 

 representing the various stages of maturity of the samples outside of 

 Minnesota, were analyzed for hydrocyanic acid before and after storage 

 in cans, with the results given in Table I. 



Table I. — Efficiency of an alkaline preservative in preventing loss of hydrocyanic acid in 



sorghum 



