EFFECTS ON IMPOVERISHED ACID SOILS. 131 



1820. Wheat the effect something better ; and continued to be 

 visible on -the weeds following, until the whole was more heavily 

 marled in 1823. 



Experiment 9. 



In the same field, on soil as poor and more sandy than 'the last 

 described, four acres were marled at one hundred and eighty 

 bushels (37 per cent.), March 1818. A part of the same was also 

 covered heavily with rotted barn-yard manure, which also extended 

 through similar land not marled. This furnished for observation, 

 land marled only manured only marled and manured and some 

 without either. The whole space, and more adjoining, had been 

 heavily manured five or six years before by summer cowpens, and 

 stable litter of which no appearance remained after two years. 



Results, 1819. In corn. The improvement from marl very evi- 

 dent ; but not to be distinguished on the part covered also by ma- 

 nure, the effect of the latter so far exceeding that of the marl as 

 to conceal it. 



1820. In wheat. In 1821 and 1822, at rest. 



1823. In corn 5J by 3J feet. The following measurements 

 were made on adjoining spaces on October 10th. The shape of the 

 ground did not admit of larger pieces, equal in all respects, being 

 measured, as no comparison of products had been contemplated at 

 first, otherwise than by the eye. 



Bush. Quarts. 

 From the part not marled, 414 corn-hills made 75 quarts * 



or per acre, 13 26 



Marled only, 414 .... 100 . 18 12 

 Manured only, 490 .... 105 . 15 5 

 Marled and manured, 490 . . . 130 . 20 20 



The growth on the part both marled and manured was evidently 

 inferior to that of 1819. This was to be expected, as the small 

 quantity of calcareous earth was not enough to fix half so much 

 putrescent manure ; and, of course, the excess was as liable to 

 waste as if no marl had been used. 



Experiment 10. 



Twenty acres of sandy loam, on a sandy sub-soil, covered in 1819 

 with marl of about 30 per cent, average proportion of calcareous 

 earth, and the remainder silicious sand at 800 bushels to the acre. 

 This land had been long cleared, and much exhausted by cultiva- 

 tion j since 1814 not grazed, and had been in corn only once in 

 four years ; and, as it was not worth sowing in wheat, had three 

 years in each rotation to rest and improve by receiving all its scanty 

 growth of weeds. The same course has been continued from 1819 

 to 1832, except that wheat has regularly followed the crops of 



