50 



CONTROL SERIES No. 54 



Series II. — Washed (a) 



(a) By "unwashed" is meant the original ground material furnished to the trade: "washed" 

 designates each product largely freed from water soluble nitrogen by successive washings with 

 water. 



Conclusions. 



Dried Blood, Dark. I'he two lots of fertilizer grade Dried Blood .showed 

 satisfactory nitrogen availahility. The direct-heat drying system employed in 

 the preparation of this product, which is probably responsible for the dark color 

 characterizing this grade of blood, apparently does not lower the quality of the 

 material as a nitrogen source. The results secured on the 1929 sample in Series 

 II, the washed product, do not confirm the low availability recorded in the 1929 

 experiment, and indicate that the material is of excellent quantity. No explana- 

 tion can be given for the low test secured in 1929. 



XTottonseed Meal. All three grades of Cottonseed Meal showed satisfactory 

 nitrogen availability, the lower protein meals leading the higher grade both in 

 dry matter yield and in nitrogen recovered. 



Darling's Tankage. Experiments with this product have given consistent 

 results for three successive years. The average availability of the total nitrogen 



