156 DISEASED CROPS CAUSED BY MARLING. 



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 earliest growth, 

 like that of corn, is not affected. About the time for heading, the 

 plants most diseased appear as if they were scorched, and when 

 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 as many grains 

 of wheat. This crop, however, suffers less than corn on the same 

 land ; perhaps because its growth is nearly completed by the time 

 that the warm season begins, to which the ill effects of calcareous 

 manures seem confined. The injury to corn is also greater in a 

 wet than a drier summer. 



When these unpleasant discoveries were first made, two hundred 

 and fifty acres had already been marled so heavily that the same 

 evil was to be expected to visit the whole. My labours, thus be- 

 stowed for years, had been greatly and unnecessarily increased; 

 and the excess, worse than being thrown away, had served to take 

 away that increase of crop which lighter marling would have 

 insured. But though much and general injury was afterwards 

 sustained from the previous work, yet it was lessened in extent and 

 degree, and sometimes entirely avoided, by the remedial measures 

 whic.h were adopted. My observation and comparison of all the 

 facts presented, led to the following conclusions, and pointed out 

 the course by which to avoid the recurrence of the evil, and the 

 means to lessen or remove it, where it had already been inflicted. 



1st. No injury has been sustained on any soil of my farm by 

 marling not more heavily than two hundred and fifty heaped 

 bushels to the acre, with marl of strength not exceeding 40 per 

 cent, of calcareous earth. 



2d. Dressings twice as heavy seldom produce damage to the first 

 crop on any soil ; and never even on the after crops on ajiy calca- 

 reous, or good neutral soil; nor on any acid soil supplied plenti- 

 fully with vegetable matter. 



3d. On acid soils marled too heavily, the injury is in proportion 

 to the extent of one or all these circumstances of the soil poverty, 

 sandiness, and severe cropping and grazing, whether inflicted pre- 

 viously or subsequently. 



- 4th. Clover, both red and white, will live and flourish on the 

 spots most injured for grain crops by marling too heavily. Thus, 

 in the case before cited of land adjacent to the pieces measured in 

 experiment 10, and equally over-marled, very heavy red clover was 



