EXPERIMENTS ON WUKAT. 181 



1845 the result was better «« to corn on plot 9, •where the salts were 

 sown earlier, than on plot 10, whire tlie top-dressing extended far 

 into the spring. Wo have had several direct instances of this kind in 

 our experience, and we would pive it as a s'lirgestion, in most cases 

 applicable, that manures for wheat, and especially ammoniacal 

 ones, should be applied before or at the time the seed is sown ; 

 for, although the apparent luxuriance of the crop is greater, and 

 the produce of straw really heavier, by spring rather than autumn 

 sowings of Peruvian guano and other ammoniacal manures, yet we 

 believe that that of the corn will not be increased in an equivalent 

 degree. Indeed, the success of the crop undoubtedly depends very 

 materially on the progress of the underground growth during the 

 winter months; and this again, other things being equal, upon the 

 quantity of available nitrogenous constituents within the soil, with- 

 out a liberal provision of which, the range of the fibrous feeders 

 of the plant will not be such, as to take up the minerals which the 

 soil is competent to supply, and in such quantity as will be required 

 during the after progress of the plant for its healthy and favorable 

 growth." 



These remarks arc very suggestive and deserve special attention. 



"The next result to be noticed," continue Messrs. Lawes and 

 Gilbert, "is that obtained on plot 6, now also divided into two 

 equal portions designated respectively Ga and 66. Plot No. 6 had 

 for the crop of 1844, superphosphate of lime and the phosphate of 

 magnesia manure, and for that of 1845, superphosphate of lime, 

 rape-cake, and ammoniacal salts. For this, the third season, it 

 was devoted to the trial of the wheat-manure manufactured under 

 the sanction of Professor Licbig, and patented in this country. 



" Upon plots 6 ', four cwts. per acre of the patent wheat-manure 

 were used, which gave 201 bushels, or rather more than two 

 bushels beyond the produce of the unmanured plot; but as the 

 manure contained, besides the minerals peculiar to it, some nitro- 

 genous compounds, giving off a very perceptible odor of ammonia, 

 some, at least, of the increase would be due to that substance. On 

 plot (Sb, however, the furtlicr addition of one cwt. each of sulphate 

 and muriate of ammonia to this so-called 'Mineral Manure,' givrs 

 a produce of 29^ bushels. In other words, the addition of ammoni- 

 acal salt, to Liebig's mineral manure has increased the produce by 

 very nearly 9 bushels per acre beyond that of the mineral manure 

 alone, whilst the increase obtained over the unmanured plot, by 

 14 tons of farm-yard manure, was only 9^^ bushels ! 



The following table gives the results of the experiments the 

 fourth ye&T, 1846-7. 



