JOO CALCAREOUS MANURES— PRACTICE, 



The same chemical action being supposed, explains wliy the power of 

 profiting by gypsum should be immediately awakened on acid soils after 

 making them calcareous— and why that manure should seldom fail, v/hen 

 applied mixed with much larger quantities of calcareous earth. 



CHAPTER IX. 



THE DAMAGE CAUSED BY TOO HEAVY DRESSINGS OP CALCAREOUS MANURE, AND THE 



REMEDY. 



Propjosition 5 — continued. 



The injury or disease in grain crops produced by marling has so lately 

 been presented to our notice, that the collection and comparison of many 

 additional facts will be required before its cause can be satisfactorily ex- 

 plained. But the facts already ascertained will at least show how to avoid 

 the danger of such injury in future, and to find remedies for the evils al- 

 ready inflicted by the injudicious use of calcareous manures. 



The earliest effect of this kind observed was in May, 1824, on the field 

 containing experiment 10. The corn on the land marled four years before 

 sprang up and grew with all the vigor and luxuriance that was expected 

 from the appearance of increased fertility exhibited by the soil, as before 

 described, (page 84.) About the 20th of May the change commenced, and 

 the worst symptoms of the disease were seen by the 11th of June. From 

 having as deep a color as young corn shows on the richest and best soils, 

 it became of a pale sickly- green. The leaves, when closely examined, 

 seemed almost transparent, afterwards were marked through their whole 

 length by streaks of rusty red, separated very regularly by other streaks 

 of what was then more of yellow than green, and next they began to shri- 

 vel and die downwards from their extremities. The growth of many of 

 the plants was nearly stopped. Still some few showed no sign of injury, 

 and maintained the vigorous growth which they began with, so as by con- 

 trast more strongly to mark the general loss sustained. The appearance" of 

 the field was such, that a stranger would have supposed that he saw the 

 crop on a rich soil exposed to the worst ravages of some destructive kind 

 of insects; but neither on the roots or stalks of the corn could any thing be 

 found to support that opinion. Before the first of August this gloomy 

 prospect had somewhat improved. Most of the plants seemed to have been 

 relieved of the infliction, and to grow again with renewed vigor. But be- 

 fore that time many were dead, and it was impossible that the others could 

 so fully recover as to produce any thing approaching a full crop for the land. 

 It has been shown in the report of the products of Exp. 1 0, what diminu- 

 tion of crop was then sustained— and that the evil was not abated in the 

 three succeeding courses of cultivation. Still, neither of the diseased 

 measured pieces has fallen quite as low as its product before marling; 

 nor do I think that such has been the result on any one acre together on 

 my farm, though many smaller spots have been rendered incapable of 

 yielding even so much as a grain of corn or wheat. 



The injury caused to wheat by marling is not so easy to describe, though 

 abundantly evident to the observer. Its earfiest growth, like that of corn, 

 is not affected. . About the time for heading, the plants most diseased ap- 

 pear as if they were scorched, and whtfn ripe will be found very deficient 

 in grain. On very poor spots, from which nearly all the soil has been 

 washed, sometimes fifty heads of wheat, taken together, would not furnish 



