THOROUGH DRAINAGE. 261 



success of each operation depends were understood. The 

 merits of subsoiling or deep ploughing, for instance, are often 

 argued without reference to any principle whatever, and 

 erroneous conclusions are no doubt frequently formed in conse- 

 quence. Whereas, if the data necessary to lead to a correct 

 view of the subject were examined, it would be observed that 

 all soils liable to become too firm, require perhaps the applica- 

 tion of all the means at the command of the farmer, to keep 

 them open and to bring and return all their parts to the 

 required depth under the influence of air and wat:?r. 



The great object of draining and other improvements, is to 

 promote fertility ; and subsoiling, and deep and perfect mixing 

 and comminution of the surface soil must, as auxiliaries to 

 thorough draining, be highly beneficial. If these prove inade- 

 quate, other means, such as the admixture of matter, will be 

 required in addition. 



If the soil is light and naturally porous, all its parts must 

 be already more or less under the influence of air and water, 

 and it possesses the advantages which subsoiling and deep 

 tillage are calculated to confer. These operations would, 

 therefore, be likely to prove less beneficial than in the case of 

 stiffer soils. 



Many soils, though absorbent in their natural state, are much 

 benefited by deep ploughing or subsoiling, especially when 

 green crops are to be grown, so that the ready filtration of 

 water through them without draining is not an imerring test, 

 as everything depends upon their nature, specific gravity, their 

 locality, and the system of cropping and management. It is 

 certain that some light soils require no deep stirring to keep 

 them open, or to bring them into their utmost state of produc- 

 tiveness ; but, on the contrary, they often require compression 

 and careful management to make and keep them sufficiently 

 firm ; hence a heavy dressing of clay or marl which assists in 

 consolidating them and increases their capacity for retaining 

 water, as well as in supplying inorganic matter in which they 

 are deficient, is often found to contribute greatly to their 

 fertility, and to enable crops to be grown upon them, for which 

 they would otherwise have been unsuitable. Thorough drain- 

 ing, liowever, by which the soil can be made perfectly absorbent 

 and dry throughout, is of much greater importance than any 



