EXPERIMENTS ON WHEAT. 173 



The manure had not been piled. It was probably taken out 

 fresh from the yard (this, at any rate, was the case when I was at 

 Rothamsted), and plowed under late in the season. And on this 

 heavy land, manure will lie buried in the soil for months, or, if un- 

 disturbed, for years, without decomposition. In other words, while 

 this 14 tons of barn-yard manure, contained at least 150 Ibs. of 

 nitrogen, and a large quantity of minerals and carbonaceous 

 matter, it did not produce a bushel per acre more than a manure 

 containing less than 12 Ibs. of nitrogen. And on plot 19, a manure 

 containing less than 15 Ibs. of available nitrogen, produced nearly 

 4 bushels per acre more wheat than the barn-yard manure contain- 

 ing at least ten times as much nitrogen. 



There can be but one explanation of this fact. The nitrogen in 

 the manure lay dormant in this heavy soil. Had it been a light 

 sandy soil, it would have decomposed more rapidly and produced 

 a better effect. 



As we have before stated, John Johnston finds, on his clay-land, 

 a far greater effect from manure spread on the surface, where it 

 decomposes rapidly, than when the manure is plowed under. 



The Deacon was looking at the figures in the table, and not pay- 

 ing much attention to our talk. " What could a man be thinking 

 about," he said, " to burn 14 tons of good manure ! It was a great 

 waste, and I am glad the ashes did no sort of good." 



After the wheat was harvested in 1844, the land was immedi- 

 ately plowed, harrowed, etc. ; and in a few weeks was plowed 

 again and sown to wheat, the different plots being kept separate, 

 as before. 



The following table shows the manures used this second year, 

 and the yield per acre : 



