CALCAREOUS MANURES— PRACTICE. JQl 



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 labors, thus bestowed for years, had 

 been greatly and unnecessarily increased— and the excess, worse than be- 

 ing thrown away, had served to take away that increase of crop which 

 lighter marling would have ensured. 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 mea- 

 sures which 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. 



2dr Dressings twice as heavy seldom produce damage to the first crop 

 on any soil — and never even on the after crops on any calcareous, or good 

 neutral soil— nor on any acid soil supplied plentifully 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 previously or subse- 

 quently. 



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 raised in 1830, by adding gypseous 

 earth, and which was succeeded by a good growth of corn, free from every 

 mark of disease, in 1832. 



5th. A good dressing of putrescent manure removes the disease com- 

 pletely, (see Exp. 11, 12, 13.) All kinds of marl (or fossil shells) have some- 

 times been injurious— but such effects have been more generally experi- 

 enced from the dry yellow marl, than from the blue and wet. 



The inferences to be drawn from these facts are obvious. They direct 

 us to avoid injury by applying marl lightly at first, and to be still more 

 cautious according to the existence of the circumstances stated as increas- 

 ing the tendency of marl to do harm. Next, if the over-dose has already 

 been given, we should forbid grazing entirely, and furnish putrescent ma- 

 nure as far as possible— or omit one or two grain crops, so as to allow more 

 vegetable matter to be fixed in the land— apply putrescent manures— and 

 sow clover as soon as circumstances permit. One or more of these reme- 

 dies have been used on most of my too heavily marled land ; and with 

 considerable, though not always with entire success, because the means for 

 the cure could not always be furnished at once in sufficient abundance. 

 Other persons, who permitted close grazing, and adopted a more scourging 

 rotation of crops, have suffered more damage,Trom much lighter dressings of 

 marl than those of mine which were injurious. 



But though the unlooked-for damage sustained from this cause produced 

 much loss and disappointment, and has greatly retarded the progress of my 

 improvements, it did not suspend my marling, nor abate my estimate of the 

 value of the manure. If a cover of -500 or 600 bushels was so strong as 



13 



