THE FOURTH EDITION. 15 



or soils employed, and to describe them accordingly. 

 In many instances, wliere experiments have been 

 made on the produce of plants, this very essential 

 point has been disregarded ; it is to this only we can 

 look for a satisfactory reason to reconcile the discord- 

 ance of results obtained from experiments, made on 

 the same kind of plant by different persons, equally 

 competent to execute the trials with care and accu- 

 racy. From the same source will be found to pro- 

 ceed the difference of opinion, respecting the impo- 

 verishing effects of different plants on the soil. 

 Some plants exhaust the soil more than others; and 

 though the preparation and the manure bestowed be 

 the same in two cases, yet a specific difference in the 

 nature of the soils, will give different results as to 

 their produce. 



The terms adopted to denote different soils, have 

 been used without precision. The term loam, for 

 instance, is defined b)^ one to be a fat earth or 

 marl, and by others, to be a mixture of clay, sand, 

 and calcareous earth, without stating the proportions. 

 In general, on referring to books on agriculture and 

 gardening, we are directed to a hazel loam, a brown 

 loam, clayey loam, or to a hungry sandy soil, bog- 

 soil, peat earth, garden mould, &.C.; but for want of 

 proper definitions of these terms, it is perplexing 

 or nearly impracticable to determine which kind of 

 soil is meant. 



The method of determining the nature of soils by 

 chemical analysis has been so simplified, that it is 

 now in the power of every practical person to ascer- 

 tain with facility the qualities of any kind of soil. 



