MANURES. 47 



The soils indicated by a natural growth of black oak, walnut and poplar, 

 and those in which such grasses as the poas and fustucas best flourish, are 

 generally most signally benefi tted by the use of lime. In short, I may observe 

 that lime has been found more or less beneficial in every description of soil in 

 this district. It is most so in hilly or rolling lands, where clay predominates; 

 less permanently so among the mica slate; and least of all on the magnesia 

 rocks. The soil on these last is rarely worth cultivating. 



The quantity of lime, per acre, which can be used advantageously, varies 

 with the condition and original character of the soil. Highly improved land 

 will bear a heavier dressing than poor land. On a soil of medium condition, 

 the usual dressing is forty to fifty bushels per acre. A deep rich soil (or lime- 

 stone land in the great valley) will receive seventy to eighty, and even one 

 hundred bushels to the acre, with advantage. On very poor land, twenty to 

 thirty bushels per acre is deemed most advantageous to commence with. 



Tne application is usually repeated every five or six years; that is, every 

 time the field comes in turn to be broken up with the plough, and as the land 

 improves, the quantity of lime is increased. The prevailing practice here, 

 (Chester county,) is to plough down the sod or lay in the fall, or early in the 

 spring, harrow it once, and then spread the lime, previously slacked to a 

 powder, preparatory to planting the field with Indian corn. 



Every field, in rotation, receives this kind of dressing; and as our farms are 

 mostly divided into about half a dozen fields, the dressing of course comes 

 once m six years, more or less, according to the number of the fields. Some 

 enterprising farmers, however, give their fields an intermediate dressing on 

 the sod, after they come into grass; which is considered an excellent practice, 

 tending rapidly to improve the condition of the land. 



The manner of opplyins the lime is as follows: It is usually obtained in a 

 caustic state from the kiln, deposited in heaps in the field where it is to be 

 spread, and water sufficient to slake it to a powder is then thrown upon it. 

 As soon as it is slaked, it is loaded into carts, and men with shovels distribute 

 it as evenly as possible over the ground. 



The crop to which it is usually applied is Indian corn, in the spring of the 

 year: say the month of April. Occasionally it is applied preparatory to M 

 ing wheat, in autumn. When used as a tj>-(l resting, on the sod, it is gene- 

 rally applied in the fall. The prevailing opinion is, that it is most advan- 

 tageously applied to the corn crop, and hence the general practice. But the 

 truth is, it is highly advantageous at any and at all seasons." 



The advantage of lime is threefold, each distinct and sepa- 

 rate. 1. It is a Neutralizcr. 2. It is a Decomposer. 3. It 

 is a Converter. 1. Lime acts as a neutralizer in all soils in 

 which phosphoric or the other acids exist in a free state. 2. 

 The geate of alumina, the least of all demanded by plants, 

 frequently abounds in soils. Long formed and sun-baked, 

 they are scarcely acted on by rain or dew; but lime decom- 

 posing these metallic and earthy geates, forms a combination 

 which, in its nascent state, is readily dissolved. It is therefore 

 a decomposer. 3. But the great use of lime is as a converter, 

 turning solid and insoluble geine, and even solid vegetable 

 fibre, in the soil, into soluble vegetable food.* 



Gypsum, otherwise sulphate of lime, or plaster of Paris, 

 as it is sometimes termed, from having been dug in great 

 quantities from the quarries at Mont Martre, is a fossil, of 

 which one hundred parts of that kind chiefly used as a manure 



* Dr. DANA'S letter. 



