62 OUGHT ALL THE MANUEE 



to plough in the farm-yard manure in the autumn, and to apply 

 any bones or guano they may use, along with the seed, in the 

 spring or early summer. So, with other applications, it is a 

 question of importance to ascertain, not only whether the manure 

 is more profitable when laid on as is usually done in some dis- 

 tricts only once in the rotation, or when applied two or three 

 several times in as many successive years ; but also whether 

 the whole of any top-dressing we may use in any given year 

 should be laid on at once, or should be divided into two or more 

 portions and applied at successive periods. For example, Mr John 

 M'Lintock, of the Harley Works, near Glasgow, made two sets 

 of experiments in 1843 upon different fields of wheat which he 

 top-dressed with saltpetre, in the one case applied altogether on 

 the 17th of April, in the other, one-half on the 17th of April, 

 and the other half on the 6th of May, with the following results 

 per imperial acre : 



Grain. Straw. 



First, No application, . . . 2689 Ib. 3372 Ib. 



Saltpetre, 84 Ib., on 17th April, 2664 Ib. 3136 Ib. 



Difference, ... 25 Ib. 136 Ib. 



The application in this case may be said to have produced no 

 economical effect. 



Grain. Straw. 



Second, No application, . . . 2552 Ib. 3148 Ib. 

 Saltpetre, 28 Ib., on 17th April, ) , ., 

 56 Ib., on 6th May, / 



Difference, . . . 516 Ib. 1352 Ib.* 



In this case there was an increase of eight bushels of grain 

 and eleven cwt. of straw. In both experiments the soil was a 

 sandy loam ; and in the first field the wheat was sown in No- 

 vember after potatoes ; in the second, in December after turnips. 

 But we are unable to determine how much of the apparent in- 

 crease in the second experiment was due to the application at 

 two successive periods rather than one -first, because it is not 

 stated if the weather in May was or was not more favourable to 

 * Transactions of the Highland Society, January 1849, p. 437. 



