364 HOW CROPS FEED. 
larger quantity depressed the yield. It is probable that less 
than 71 lbs. would have produced an equal effect, since 47 
lbs. gave so nearly the same result. The ash composition 
of bar ley, grain, and straw, in 100 parts, is as follows, 
according to Zoeller, (H. C. G., pp. 150 to 151): 
Grain. Straw. 
Potash, 18.5 12.0 
Soda, 3.9 46 
Magnesia, 7.0 30 
Lime, 2.7 7.3 
Oxide of iron, 0.7 1.9 
Phosphoric acid, 32.4 6.0 
Sulphuric acid, 2.8 2.8 
Silica, 31.1 59 7 
Chlorine, 1.1 26°-* 
The proportion of ash in the air-dry grain is 24 per 
cent, that in the straw is 5 per cent, (Ann. Ch. u. Ph. 
CXII, p. 40). Assuming the average barley crop to be 
33 bushels of grain at 53 lbs. per bushel = 1,750 Ibs., and 
one ton of straw,* we have in the bariey crop of an acre 
the following quantities of ash-ingtedients: 
ze ‘ 2 
aie : > "3 poe 
gS s 8 © § $8 33. 9.7 
s & 8 By > Ce gee eee 
Barley Grain, 43% 81 1% B81 12 08 142 190008 
Straw, 100.00 120 46 30 73 19 60 28 26 
| 
| 
| 
| 
Total, 143.75 20.1 6.3 6.1 8.5 2.2 20.4 4.0 3.1 
In the account of Hellriegel’s experiments, it is stated 
that the maximum barley crop in some other of his trials, 
corresponds to 8,160 lbs. of grain, or 154 bushels of 53 
Ibs. each per acre. This is more than 4} times the yield 
above assumed. 
The above figures show that no essential ash-ingredi- 
ent of the oat crop is present in larger quantity than 
potash. Phosphoric acid is quite the same in amount, 
* These figures are employed by Anderson, and are based on Scotch statistics 
