16 EF. A. CARLSON 
Removal of nitrogen from the soil in crops grown on the plats in 
Series I 
»S ¢ 
The amounts of nitrogen removed in the crops were esti- 
mated and are recorded in table 5. The nitrogen is expressed 
in pounds per acre for the ten-years period. 
TABLE 5. Amount oF NITROGEN IN Crops. SERIES I 
Burnt [Nitrogen in crops 
Plat Crop Fertilizer lime |(pounds per acre, 
(pounds )jtotal for ten years) 
7092 | Rotation with- | Farm manure 0 684 
out legume 
7008 Hole eee Farm manure 9,000 798 
7005 | Rotation with | Farm manure 0 817 
legume 
7011 | Rotation with Farm manure 9,000 948 
legume 
7006 | Grass Farm manure 0 325 
7012 | Grass Farm manure 9,000 354 
79014 | Rotation with- | Farm manure and K,SO, 0 844 
out legume 
7015 | Rotation with- | parm manure and K.SO, 9,000 868 
out legume 
It appears that the nitrogen varies with different crops. 
The greatest removal of nitrogen was in the crops in rotation 
with legumes. The hay crops removed less than half the 
amounts of nitrogen estimated in the crops in rotation with 
legumes. These results are of extreme importance in consider- 
ing the total nitrogen in the soils of these plats recorded in 
table 3, in which, as already stated, it is shown that the plats 
kept ‘in grass increased in nitrogen in the first foot, while the 
plats in rotation with legumes and those in rotation without 
legumes decreased in nitrogen. The fact that less nitrogen was 
removed from the grass plats may aid in some degree in explain- 
ing these differences in percentages of nitrogen. 
