CALCAREOUS MANURES— PRACTICE. jgS 



same manner as before, by destroying the last formed acid, and fixing the 

 last supply of vegetable matter. Thus perhaps five or ten bushels more 

 may be added to the previous product, and a power given to the soil gra- 

 dually to increase as much more, before it will stop again for similar rea- 

 sons, at a second maximum product of forty or fifty bushels. I pretend 

 not to fix the time necessary for the completion of one or more of these 

 gradual changes ; but as the termination of each, and the consequent ad- 

 ditional marling, will add new profits, it ought to be desired by the farmer, 

 instead of his wishing that his first labor of marling each acre may also 

 be the last required. Every permanent addition of five bushels of corn, to 

 the previous average crop, will more than repay the heaviest expenses that 

 have yet been encountered in marling. But whether a second application 

 of marl is made or not, I cannot imagine such a consequence, under judi- 

 cious tillage, as the actual decrease of the product once obtained. My 

 earliest marled land has been severely cropped, compared to the rotation 

 supposed above, and yet has continued to improve, though at a slow rate. 

 The part first m.arled, in 1818, had only four years of rest in the next fif- 

 teen ; and yielded nine crops of grain, one of cotton, and one year clo- 

 ver twice mowed. This piece, however, besides being sown with gypsum, 

 (with little benefit,) once received a light cover of rotted corn-stalk ma- 

 nure. The balance of the same piece of land (Exp. 1 ) was marled for the 

 crop of 1821 — has borne the same treatment since, and has had no other 

 manure, except gypseous earth once, (in 1830,) which acted well. These 

 periods of twelve and fifteen years (even though now extended to and 

 confirmed by nine years more of experience) are very short to serve as 

 grounds to decide on the eternal duration of a manure. But it can scarce- 

 ly be believed that the effect of any temporary manure, would not have 

 been somewhat abated by such a course of severe tillage. Under milder 

 treatment, there can be no doubt that there would have been much greater 

 improvement. 



If subjected to a long course of the most severe cultivation, a soil could 

 not be deprived of its calcareous ingredient, whether natural or artificial : 

 but though still calcareous, it would be, in the end, reduced to barrenness, 

 by the exhaustion of its vegetable matter. Under the usual system of ex- 

 hausting cultivation, marl certainly improves the product of acid soils, and 

 may continue to add to the previous amount of crop, for a considerable 

 time ; yet the theory of its action instructs us, that the ultimate result of 

 marling, under such circumstances, must be the more complete destruction 

 of the land, by enabling it to yield all its vegetable food to growing plants, 

 which would have been prevented by the continuance of its former acid 

 state. An acid soil yielding only five bushels of corn may contain enough 

 food for plants to bring fifteen bushels — and its production will be raised to 

 that mark, as soon as marling sets free its dormant powers. But a calca- 

 reous soil reduced to a product of five bushels, can furnish food for no 

 more, and nothing but an expensive application of putrescent manures, can 

 render it worth the labor of cultivation. Thus it is, that soils, the improve- 

 ment of which is the most hopeless without calcareous manures, will be 

 the most certainly improved with profit by their use. 



