BULLETIN OF THE BUSSEY INSTITUTION. a9 
so moist as that of Scotland, it has been noticed * that rape-dust, which 
was formerly somewhat extensively employed there as a manure, often 
fails to be of use in very dry seasons and on dry soils. An adequate 
supply of moisture is essential to the production of its full effects. 
But since the nitrogen in rape-dust is notoriously more active and 
available for the use of plants than that in ordinary peat and loam, the 
fact that the usefulness of rape-dust depends so largely upon the con- 
tingency of a favorable season or a moist soil, teaches an important 
lesson. Not only does it suggest most emphatically that the less active 
soil-nitrogen needs to be kept similarly moist in order to its best action, 
but it points directly to the necessity of studying the soil-nitrogen for 
its own sake, of noting its peculiarities, and of determining clearly what 
conditions are most favorable to its usefulness. From the reports of 
the various agricultural societies of New England, it appears that mere 
peat or pond-mud often fails to produce useful effects when applied to 
land that seems to stand in need of vegetable matters, while in other 
instances distinctly beneficial effects are noticed. These differences are 
undoubtedly due in part to variations in chemical composition of the 
several peats or muds; but there can be little question that the failure 
of the peat or mud to act as a nitrogenous manure must often be at- 
tributed to the unfavorable conditions as regards moisture in which these 
substances were placed. ‘They would be little likely to fail upon land 
needing nitrogen so situated that any organic matters that might be 
added to it would naturally be kept moist and mellow. Lut, as it hap- 
pens, the land of fields thus advantageously placed is commonly so 
well charged with organic matters that peat alone is, comparatively 
speaking, seldom applied to it. Too much moisture is to be deprecated, 
of course. ‘The soil must not be changed to a swamp, nor be kept so 
wet that it could become in the least degree boggy or sour. A prop- 
erly moist and mellow soil may often be seen in fields and pastures 
on moving some stone, or clod, or piece of wood that has lain some time 
undisturbed, and observing the condition of the earth beneath. Irom 
the color and vigor of the grass, moreover, about the stone, it may be 
seen how useful the soil-nitrogen has there been found by the plants 
that had access to it. As an exhibition of the effects upon which the 
usefulness of mulching chiefly depends, this illustration leaves little to 
* Anderson, in his ‘‘ Elements of Agricultural Chemistry,” Edinburgh, 1860, 
p. 196. 
