ON THE IMPROVEMENT OF SOIL. 167 



undergone the process of fermentation, so that the 

 straw is not yet wholly decomposed, is best adapted to 

 strong compact soils : the tubular remnants of straw an- 

 swer the purpose of so many little props to support the 

 earth, and afford a passage for the air, thus rendering the 

 soil lighter ; besides, the completion of the fermentation 

 taking place after the manure is buried in the soil, has 

 the advantage of raising its temperature. 



Emily. Since the putrid fermentation reduces every 

 animal and vegetable substance into its primitive ele- 

 ments, there are none, I suppose, which may not be con- 

 verted into manure ? 



Mrs. B. None ; but some bodies are more readily de- 

 composed than others : it is from domestic animals that 

 the best manure is obtained. In maritime districts, fish, 

 when sufficiently abundant, is sometimes used to manure 

 the land. They are easily decomposed, and afford a con- 

 siderable quantity of nourishment. Even such hard sub- 

 stances as horn, hair, feathers, and bones, are all resolva- 

 ble into their primitive elements, and make excellent ma- 

 nure ; but, owing to their dry nature, require a longer pe- 

 riod for their decomposition. Such substances are cal- 

 culated not for annual harvests, but to fructify the soil for 

 a produce of much longer duration, such as that of olive- 

 trees and of vineyards. 



Vegetable manure does not always undergo fermenta- 

 tion previous to being buried in the soil : green crops, 

 such as lupins and buck-wheat, are sometimes ploughed 

 in, and thus buried for the sole purpose of enriching the 

 soil. A green crop contains a considerable quantity of 

 water ; and the plants, when buried, serve to lighten the 

 soil previous to decomposition, and subsequently to en- 

 rich it with food for the following crop. This species of 

 living manure is particularly calculated for hot countries, 

 on account of the abundance of moisture it incorporates 

 with the soil. 



Emily. I have seen sea-weeds used as manure, which 

 has at least the advantage of being a gratuitous crop. 



Mrs. B. Gratuitous in some respects, but requiring a 



918. When manures perform a part of their fermentation buried in 

 the soil, what is the consequence? 919. What are the best manures'? 

 920. What is said of horns, hair, feathers, and bones for manure, and 

 for what are they suited 1 921. And of buckwheat and lupins'! 922. 

 And of jjreen crops buried in the soil 1 ? 923. For what countries 

 is this species of manure particularly calculated 1 ? 



