Dec. 15,1925 Mineral Composition of Sunflowers Grown for Silage 1171 
Figure 3 shows the difference in the mineral composition of sun¬ 
flowers and corn when expressed as percentage of the dry material 
and when expressed as pounds removed per acre, assuming an arbi¬ 
trary yield of 10 tons for each crop. The moisture content of sun¬ 
flowers was placed at 80 per cent and com at 70 per cent, which is 
near the average figure for each crop. 
Comparing the percentage composition it is seen that sunflowers 
contain more than three times as much potassium oxide, eight times 
as much calcium oxide, and twice as much magnesium oxide, as does 
corn. The percentage composition in respect to phosphorus pentoxide, 
sulphur, and other elements is about the same for both crops, there 
being slightly greater percentages in sunflowers than in corn. 
In spite of the fact that a lQ-ton yield of sunflowers, as cut for 
silage, yields only 4,000 pounds of anhydrous material, while 10 tons 
of com yields 6,000 pounds, it is found that the amount of bases 
removed by sunflowers is still much greater than is removed by com 
as cut for silage. The two elements showing the greatest differences 
are potassium and calcium, 150 pounds of potassium oxide and 
87.8 pounds of calcium oxide being removed by sunflowers as against 
68.9 pounds of potassium oxide and 16.6 pounds calcium oxide by 
corn. Magnesium oxide is about 1)4 times greater, there being 24.24 
S ounds removed by the sunflowers and 18.3 pounds by the com. 
ulphur is removed in approximately the same amounts by both 
crops, sunflowers removing 9.84 pounds and com 9.78 pounds per 
acre. More phosphorus pentoxide is removed by com than by sun¬ 
flowers, the amounts being 29 pounds and 23.5 pounds, respectively. 
While the percentage of nitrogen is approximately the same in 
sunflowers and com, the amount removed by the 10-ton crop of com 
is greater than that removed by a corresponding crop of sunflowers, 
due to the greater amount of anhydrous material. A 10-ton yield of 
corn contains 88.8 pounds nitrogen as against 61.3 pounds for the 
similar yield of sunflowers. 
The reason that low yields of crops somtimes follow sunflowers may 
be due to the heavy draft which a sunflower crop makes on the soluble 
minerals of the soil, a heavy crop of sunflowers requiring especially 
a large supply of potassium and calcium. It is readily seen, there¬ 
fore, that sunflowers, when grown, should be included in a rotation. 
SUMMARY 
The composition of the ash of sunflowers has been determined for 
different systems of plantings and for different stages of growth. 
A comparison of the minerals removed by 10-ton crops of sun¬ 
flowers and corn is given. 
Sunflowers draw more heavily than corn upon certain soil ele¬ 
ments, especially potassium and calcium. 
