192 RATES OP INCREASE OF MARLED CROPS. 



before being marled, and also the most worthless of all known 

 marled soils. And yet a three-fold product has been usually ob- 

 tained on these lands by marling alone, within four or at,rnost eight 

 years after the application of marl. Still, this land, as well as the 

 most sandy, wants only greater depth of soil and abundance of 

 vegetable matter, to become fertile and valuable. 



While then calcareous manures may be counted on to produce 

 great improvement on all soils not naturally provided with them 

 and to show a greater percentage of increase on the worst than on 

 better soils, and a remunerating profit on all ( except those few 

 already calcareous ) still, it will be far more profitable to marl 

 some soils than others. Dung, or other alimentary manure in the 

 best condition for use, increases vegetation nearly in proportion to 

 the quantity of the manure, and without regard or proportion to the 

 previous product of the soil. Thus, a wasteful application of dung 

 might, in a single year, increase the production of an acre of very 

 poor land, from 5 bushels to 50 bushels of corn. But calcareous 

 manures improve production somewhat in proportion to the previous 

 power of the soil; and if the original product was very low, the 

 addition thereto of 100 or even 200 per cent., made on the first 

 crops after marling, will show still but a poor product. These re- 

 remarks and illustrations are designed for the instruction of those 

 beginners who deem it important to learn on what kinds of soil to 

 apply their marl. In more general terms I would answer, " apply 

 it to all soils not already calcareous j" for however different may be 

 the measure of profit, I have never known marl applied unprofitable 

 in regard to place, if applied judiciously in manner. Of course I 

 refer to soils having some previous productive power and some 

 tenacity j and not to such naked sands, drifting with the winds, 

 as are seen in parts of North Carolina, South Carolina, and Georgia. 



CHAPTER XXII. 



THE EXTENT OF DURATION OF THE EFFECTS OF CALCAREOUS 

 MANURES. 



PROPOSITION 5 continued. 



In advance of the discussion of the general question of the per- 

 manency of calcareous manures, I will here state the facts in regard 

 to duration of effects observed and known of my own oldest prac- 

 tice. This extent of experience is indeed much too short to be 

 considered as the slightest evidence of such permanency of effect as 



