Wheat-Steaw and its Value to the Land. 715 



its relations with Chemistry" (Vol. 3, p. 63), quotes from S. W. 

 Johnson some very instructive fig-ures reoardiug the materials removed 

 from the soil by an acre of wheat. He found the total weight of the 

 crop — grain and straw together — to be 6440 lb. Of this 1840 lb. was 

 grain and 4600 straw. The entire crop takes out of the soil 120 lb. 

 of potash, nitrogen, and phosphoric oxide; of this 120 lb., 59 lb. 

 goes into the grain and 61 lb. into the straw. Moreover, of the 120 lb., 

 48 lb. consists of nitrogen, 23 lb. of phosphoric oxide, and 49 lb. 

 of potash. That is to sny, the wheat crop, taken as a whole, needs 

 roughly half as much of phosphoric oxide as of eitlier nitrogen or 

 potash. It is, however, when we consider the composition of the grain 

 and straw separately that we notice the striking difference. Of the 

 48 lb. of nitrogen 34 lb. pass through the straw into the grain, and 

 only 14 lb. remain permanently m the straw; of the 23 lb. of 

 phosphoric oxide, 15 lb. pass over into the gTain and only 8 lb. 

 remain in the straw; with potash, on the other hand, the conditions 

 are reversed : out of the 49 lb. no less than 39 lb. are ultimately 

 found in the straw, while oidy 10 lb. are transferred into the grain. 

 The fact is that, as tiie grain of the maturing crop ripens, most of the 

 phosphoric oxide and nitrogen pass up out of the stalk and lodge in 

 the grain. 



Consider now what it would mean if all the grain were sold off 

 the f ana and all the straw got rid of by burning or otherwise ; every 

 acre of cultivated soil would, under the above conditions, lose about 

 48 lb. of nitrogen, 23 lb. of phosphoric oxide, and 49 lb. of potash, 

 all of which would have to be returned to the soil in the form of 

 fertilizers. If only the grain were sold off and the straw put back 

 into the soil, the yearly loss per acre to be made good would amount 

 to 34 lb. of nitrogen and 15 lb. of phosphoric oxide, but only 10 lb. 

 of potash. In other words, the quantity of potash lost to the soil 

 by disposing of botii grain and straw is five times as great as when 

 only the grain is disposed of. 



Of course the latter argument would not apply if the straw were 

 burnt and the ashes uniformly distributed over the stubble lands, but 

 such a course presents some practical difficulties, and even then the 

 loss of humus and nitrogen would still occur. 



The manurial value of straw has of late been the subject of 

 investigation in some of the United States experiment stations, par- 

 ticularly those of the States of New York, South Dakota, and Illinois. 

 At the first-named station straw has been valued for purely fertilizing 

 purposes at fiom 16s. 8d. to 25s. per ton, while South Dakota valued 

 it at from 8s. 4d. to 20s. lOd. per ton. In this connection the 

 American Ferttlizer remarks that to burn or to waste straw is like 

 burning real money, seeing that straw is a richer fertilizer than stable 

 manure, containing more nitrogen, two and a half as much times as 

 mu(di phosphorus, more potash, and three times as much humus- 

 ma kill,?: materials. In support of this statement the following 

 percentage composition of straw and of stable manure is quoted : — 



Straw. Manure. 



Nitrogen .50 .48 



Potash 30 to .90 .40 



Phosphorus 25 .10 



Moistijre 25.00 74.00 



