20 BULLETIN 353, U. S. DEPAKTMEXT OF AGRICULTURE. 



were split in the Hays samples, while in the Amarillo samples the 

 stems were left entire. Sphtting the stems when collecting sorghum 

 samples greatly accelerates air drying and probably adds to the uni- 

 formity of the dried samples. This practice is recommended in the 

 preparation of sorghum samples for correcting yields. 



AMOUNT OF MOISTURE IN AIR-DRY SAMPLES. 



The amount of moisture in the air-dry material depends not only 

 upon the humidity of the atmosphere but also on the nature of the 

 material in the sample. The sorghums, unless allowed to remain 

 an extraordinary time under conditions suited for drying, retain a 

 considerable percentage of moisture because of their large stems 

 with the hard outer walls. Alfalfa, on the other hand, being quite 

 succulent and leafy, loses its moisture rapidly and rather completely. 

 Alfalfa at Chico had 9.7 per cent of moisture in the air-dried mate- 

 rial, wliile at Arhngton Farm, Va., there was 10.4 per cent. This 

 difference probably represents the effect of the different degrees of 

 humidity at the two places. 



Timothy at New London, Ohio, retained 14.7 per cent of moisture 

 in the air-dried material, while the mixture of tall oat-grass and orchard 

 grass at Arlington Farm, Va., retained 17.9 per cent. Sorghum at 

 Amarillo, where the stems were not spht in the samples, retained an 

 average of 32.7 per cent. It is unfortunate that dry-matter deter- 

 minations were not made on the samples collected at Hays, Kans., 

 as this would have given an opportunity to compare with the Ama- 

 rillo samples others in which the stems were spht and the drying 

 was much more complete. 



The above percentages no doubt represent fairly accurately the 

 moisture percentages which may be expected in the air-dry samples 

 of these different crops. 



EFFECTS OF DRYING SAMPLES IN THE SUN AND IN THE SHADE. 



To compare the relative moisture content of air-dry material 

 allowed to cure in the shade with that cured in the direct sunshine, 

 two sets of alfalfa samples were taken at Chico, Cal., and two sets 

 of the mixture of tall oat-grass and orchard grass were prepared at 

 Arhngton Farm, Va., one set at each station being placed in the 

 shade to cure, wliile the corresponding set was cured in the sun. 

 The results, as given in Table V, show that while the total shrink- 

 age was greater in the shade-cured samples at both places the mois- 

 ture content of the air-dry material was a little less in the siui-cured 

 samples at Chico and a little greater in those cured in the same way 

 at Ai'hngton Farm. 



