CALCAREOUS MANURES— PKACTICE. jqq 



Marling deepens cultivated sandy soils, even lower than the plough may 

 have penetrated. This was an unexpected result, and when first observed 

 seemed scarcely credible. But this effect also is a consequence of the 

 power of calcareous earth to fix manures. As stated in the foregoing 

 paragraph, the soluble and finely divided particles of rotted vegetable mat- 

 ters are carried by the rains below the soil ; but as there is no calcareous 

 earth there to fix them, they must again rise in a gaseous form, after their 

 last decomposition, unless previously taken up by growing plants. But 

 after the soil is marled, calcareous as well as putrescent matter is carried 

 down by the rains as far as the soil is open enough for it to pass. This 

 will always be as deep as the ploughing has been, and somewhat deeper 

 in loose earth; and the chemical union formed between these different 

 substances serves to fix both, and thus increases the depth of the soil. 

 This effect is very different from the deepening of a soil by letting the 

 plough run into the barren sub-soil. If, by this mechanical process, a soil 

 of only three inches is increased to six, as much as it gains in depth, it 

 loses in richness. But when a marled soil is deepened gradually, its dark 

 color and apparent richness are increased, as well as its depth. Formerly, 

 single-horse ploughs were used to break all my acid soils, and even these 

 would often turn up sub-soil. The average depth of soil on old land did 

 not exceed three inches, nor two on the newly cleared. Even before marl- 

 ing was commenced, my ploughing had generally sunk into the sub-soil — 

 and since 1825, most of this originally thin soil has required three mules, 

 or two good horses to a plough, to break the necessary depth. The soil is 

 now from six to eight inches deep generally, from the joint operation of 

 marling and deepening the ploughing a little in the beginning of every 

 course of crops ; and to that depth, or very nearly, Ihe land is now ploughed 

 whenever preparing for corn, or for wheat on clover. 



Since marling was begun, the deepening of the soil has much more 

 generally preceded than followed the deepening of the ploughing. How 

 destructive to the power of soil this present depth of ploughing would have 

 been, without marling, may be inferred from the continued decrease of the 

 crop, through four successive courses of a very mild rotation, on the spot 

 kept without marl in experiment 10. Yet the depth of ploughing there 

 did not exceed six inches, and depths of nine and even twelve inches were 

 tried, without injury, on parts of the adjacent marled land. 



This remarkable and valuable effect of marling, in deepening the soil, 

 is increased in action by the sub-soil being sandy, which is commonly 

 deemed the worst kind of sub-soil. Land having a clay sub-soil, which is 

 known in common parlance as land with " a good foundation," is almost 

 universally prized ; and that impervious sub-soil is supposed necessary to 

 prevent the manure and the rains from sinking, and being lost. And such 

 maybe among the disadvantages, before marling, of poor land having a 

 sandy sub-soil. But not so after marling. While the open texture of 

 such a sub-soil permits so much of the water as is superfluous and injurious 

 to sink and disappear, and the combined manures to sink enough to deepen 

 the soil, (by converting barren sub-soil to productive soil,) the attractive force 

 of the calcareous earth, for both putrescent matter and moisture, will much 

 more effectually prevent either from being lost to the soil, than the mechani- 

 cal obstruction of a clay sub-soil. Great as are the objections entertained 

 by most farmers to sandy sub-soils, or to what they call "land without any 

 foundation," I would decidedly prefer such to lands having an impervious 

 clay sub-soil— supposing both to be equally barren. The subjects of all 

 my experiments stated as made on acid sandy loams, had also sub-soils of 

 yellow and barren sand; and on such lands have been made my greatest 

 and most profitable improvements by marling. However, a sub-soil (and 



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