[AsSEMBLt 
bined with some vegetabte acid. The decomposition of gravet, 
pebbles and rock, has been observed to be a benefit to vegetation, 
and as the rapidity of decomposition depends on the surface ex- 
posed, it follows, that rf such materials be ground fijie, and sowed 
upon the soil like plaster of paris, a more decided benefit would 
result. This has been partially tried with success, and it is to be 
hoped that the intelligent farmers of this State will give it a more 
thorough trial. 
The potash of commerce is all derived from wood ashes, and 
plants originally derived it from the soil of the decomposed rock. 
Marine plants afford soda, and even wood ashes from maritime dis- 
tricts contain much of this alkali, mixed with potash. 
Iron, in some states of combination, exercises a beneficial influ- 
ence on vegetation; yellowish and reddish soils almost always con- 
tain iron, and are generally productive. 
The value of marls for manures is well known. The term marl 
is usually restricted to the earthy carbonate of lime, which is more 
or less argillaceous, but in New-Jersey, several mineral substances 
have been used with advantage on soils, and the term marl is ap- 
plied to all of them. The most valuable of these marls is a green 
sandy mineral, composed of silex, iron and potash, which acts as 
a powerful manure; and it is hoped that this stratum will yet be 
found on Long-Island; and if so, it would be more valuable than 
mines of gold. 
Besides the proper mineral constituents of soils, their organic 
contents are very importan t, inasmuch, as by the decomposition of 
animal and vegetable substances, materials capable of solution in 
water, and containing suitable food for plants, are presented to 
their absorbent vessels. 
This is not a proper place to discuss the subject of manures; but 
still, it may be proper to remark, that in some parts of my district, 
much benefit would result from an occasional variation and change 
of manures, as well as from a double and triple rotation of crops. 
It is a well known fact, that ground, constantly cuiiivaled with the 
same crop, is soon worn out, even if well manured, because the 
excrementitious matter of a plant will not serve for its own food, 
although it will for others. This is finely illustrated in the suc- 
cessive natural changes in the growth of timber in our forests. 
