INSPECTION OF COMMERCIAL FERTILIZERS 41 



The experiment was run in two series to show (1) the availability of the total 

 nitrogen and (2) the availability of the water insoluble nitrogen. Necessary 

 checks were run with double the amount of nitrogen from dried red blood, the 

 standard nitrogen source, in order to prove that in the minimum nitrogen apph- 

 cations the full effect of the nitrogen would be secured. Checks were also run 

 by usirfg increased amounts of the basic fertilizer application (phosphoric acid 

 and potash). 



Water was supplied by both sub-irrigation and surface application in amounts 

 representing 50 per cent of the water holding capacity of the soil mixture until 

 hot weather when it was increased to 60 per cent. 



Japanese barnyard millet was the crop grown. All pots had ten plants during 

 the early part of the experiment but in each of eight pots (29, 35, 36, 50, 58, 71, 

 96 and 111) only nine plants reached full growth due to a wind storm occiuring 

 on July 13 which broke one plant from each pot. On July 20 a premature yellow- 

 ing was noted on all pots. This, however, did not stop growth. Pot 117 had 

 to be planted over two weeks after the first planting. It was allowed to grow 

 two weeks after the crop from the other pots had been harvested, so that the 

 length of the growing season was the same. 



With the exceptions noted above, the experiment was conducted the same as 

 described on pages 11 and 12, Control Bulletin 25. 



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

 carbonate on yield of dry matter and nitrogen assimilated, six additional pots 

 were included in the experiment. To each of two pots were added two, four 

 and six grams of a mineral containing about 38 per cent of manganese carbonate 

 with some manganese silicate (36.65% Mn304). In addition to the manganese 

 the mineral contained 18 per cent calcium oxide, 5 per cent magnesium oxide, 

 and 4.95 per cent ferric oxide, largely in form of carbonates. The six pots received 

 the basic fertilizer application, including lime, common to all of the other pots, 

 and the nitrogen was supplied in unit quantity (.42 gram) from dried red blood. 

 In the preparation of the soil, fertilizer appUcation, and general care of the 

 experiment including the harvesting of the crop, credit should be given to Mr. 

 Harold R. Knudsen of the Department of Agronomy of the Massachusetts 

 Agricultural College. 



The following table shows the yield of dry matter and the nitrogen recovered 

 in the above-ground parts of the plant; the nitrogen availability of each product, 

 from the standpoint of both total and water insoluble nitrogen and on the basis 

 of yield of dry matter and nitrogen recovered from dried red blood being placed 

 at 80. The activity of the total and water insoluble nitrogen in each product 

 as shown by the two laboratory methods is also given. 



