20 



ON THE CONTINUED CULTIVATION OF WHEAT. 



together, produced in each experiment, is stated. The follow- 

 ing exhibits the quantity of grain obtained from each crop, per 

 rood : — 



On comparing this table with the first one, it will be found that 

 the same general result appears with regard to the grain as was 

 noticed respecting the entire crop ; namely, tliat the good effect 

 produced by the various salts the first year does not continue to 

 the third and fourth year ; but in the case of the grain, they 

 seem to produce but little effect after the second year. In the 

 first year, each of the eleven salts employed increased the yield 

 of grain ; in the second year, only seven of them, namely, the 

 phospliate and sulphate of lime, sulphate of ammonia, muriate 

 and sulpliate of potash, sulphate of magnesia, and common salt ; 

 in the third year, only one salt, the sulphate of potash ; in the 

 fourth year, only the muriate of ammonia ; and in the fifth year, 

 the sulphates of lime and of soda. It is evident, tlierefore, that 

 the effect produced in the fifth year by seven of the salts em- 

 ployed was only an increase of straw, and did not also indicate a 

 corresponding increase of grain. 



In order more completely to exhibit this, the results of the 

 two preceding tables have been reduced into the following one, 

 which shows the proportion of grain to the whole produce; the 

 numbers given showing the proportion of grain in 1000 parts. 



