58 CONTROL SERIES No. 51 



Nitrogenous Tankage. About 51 per cent of the total nitrogen is in water 

 insoluble form. Although the nitrogen activity is above the passing mark by the 

 laboratory methods, the vegetation test shows the water insoluble nitrogen to be of 

 inferior quality. In 1928 it was found to be of passing quahty, although about 20 

 per cent less available than the water insoluble nitrogen from animal tankage. 

 This completes two years' experiments with this material. 



Agrinite. About 69 per cent of the total nitrogen is in water insoluble form. 

 This completes three years' experiments with this product. All of the tests have 

 shown the water insoluble nitrogen to be of passing quahty, but from 10 to 20 per 

 cent below that recorded for fish and animal tankage. ' 



Hynite. About 80 per cent of the total nitrogen is in water insoluble form and 

 shows an availability of about 50 per cent, which is about 13 per cent under re- 

 sults recorded for 1928. In 1927 and 1926 the water insoluble nitrogen was classed 

 by the vegetation tests as of inferior quality. The availability of the total nitro- 

 gen is about 61 per cent, as compared with dried red blood at 80 per cent. 



Avail Tankage. About 81 per cent of the total nitrogen is in water insoluble 

 form and of inferior quaUty, as measured by both the vegetation test and both 

 laboratory methods, being about 30 per cent imder that for fish. This completes 

 three years' experiments with this material during which consistent results have 

 been secured. In only one year was the water insoluble nitrogen found of passing 

 quality (50 per cent available). The availabiUty of the total nitrogen is only 

 about 46 per cent, as compared with about 50.5 and 58 per cent for 1927 and 1928, 

 respectively. 



Peruvian Guano. About 63 per cent of the total nitrogen is in water insoluble 

 form. The availability of both the total and the water insoluble nitrogen is 

 higher than for dried i*ed blood which is used for the standard. These results 

 confirm those secured in 1928 on a similar sample. It would seem that the alka- 

 Une laboratory method was not reliable in measuring the activity of the water 

 insoluble nitrogen in this material as it has shown results below 50 per cent each 

 year. The neutral laboratory method gives satisfactory results on this product. 



Darling's Tankage. This completes two years' experiments on this product. 

 About 64 per cent of the total nitrogen is in water insoluble form, and in quality 

 from 15 to 17 per cent under fish and animal tankage. 



Supernite. About 87 per cent of the total nitrogen is in water insoluble form. 

 The availability of both the total and the water insoluble nitrogen is satisfactory 

 and confirms results secured in 1928 on a similar sample. 



Uric Acid. This years' results confirm the availabiUty secured in the 1928 

 experiment on the same sample, the quality of the nitrogen surpassing that from 

 dried red blood used as the standard. 



The Effect of Manganese Salts on Yield of Dry Matter and Recovery of 



Nitrogen. 



In order to obtain data as to the effect of varying amounts of manganese sulfate 

 on yield of dry matter and nitrogen assimilated, as well as a comparison of the 

 effect of manganese carbonate with manganese sulfate, ten additional pots were 

 included in the experiment. All of these pots received the unit quantity of nitro- 

 gen (.42 gram) in the form of dried red blood. The same basic fertilizer used in 

 the main experiment was used in these pots also, except that in the case of the pots 

 receiving manganese carbonate and one pair of pots receiving manganese sulfate, 

 all the phosphoric acid was derived from 16% superphosphate instead of from 

 equal parts of superphosphate and basic slag phosphate. 



One pair of pots received 2.6 grams of a mineral containing 36.65% Mn304 in 

 the form of manganese carbonate with some manganese silicate. This mineral 

 was the same product that was used in the 1928 experiment in two, four and six- 



