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As we are engaged in discussing general principles, it is no part of the subject to consider the 

 case of particular soils and manures ; but it may be remarked with regard to these, that if the soil be 

 peculiar, as calcareous, green sand, etc., or the accessible manures, as gypsum, marl, refuse fish, be not 

 perfect composts, the rotation must be adapted to the case and does not require the elaborate system 

 necessary for more complex soils and manures. AYe.must either give such land the complex 

 character of the most fertile soils, an expensive process, or adapt the crops to meet its defects. But 

 an opinion is not to be hastily formed of the nature of any soil ; we may readily ascertain if clay or 

 sand predominate, if it be rich in organic matter or lime, but before an accurate conclusion can be 

 reached we must be certain that it does not contain alkaline silicates, phosphoric or sulphuric acid, 

 and these are not readily detected even in the richest soils. 



When the land or maniu-e contains every kind of plant-food in legitimate proportion, with no 

 great excess of any, as is the case in good soils, the problem to be solved is the system of rotation 

 which shall economize all these ingredients. As to the question of market, it is local ; nor do 

 we consider whether grazing be adopted or the crops directly sold, as this in no way interferes with 

 the principles in hand. If we sell oxen, sheep or wool, we deprive the soil of certain of its saline 

 and organic matters, and the rotation must be filled up so as not to waste stich as are not sold in this 

 form. If we employ complex manures, true economy does not alter the rotation, each crop is 

 enlarged, but the substances removed from the land or lost will be similar. It may be well to con- 

 sider one point more fully. If a short rotation be adopted to improve the soil, a time will arrive 

 when the improvement being effected, a new class of more exhausting plants may be introduced, but 

 these are in all cases introduced according to the same principles. There is nothing gained after the 

 soil lias reached a certain tilth in continuing the improving system, the object is now to reap our 

 reward ; but to do this in such a way that at the end of the rotation the soil shall not have fallen 

 below a certain standard, it is then to be refreshed either by manure, meadow grasses, luccrn or other 

 suitable means not now under consideration, but belonging to the topic of improving the soil, and 

 not that of rotations. 



Tiie farm having reached its high point of tillage, by suitable means, is now to be cropped for 

 profit, and reduced thereby to a certain practical standard — what are the general principles on which 

 this cropping is to be conducted? Obviously by a system of rotation, during which every saline 

 and azotized matter that liecomes soluble is removed, and no part is wasted. This can be accom- 

 plished only by introducing such crops as have severally an aflinity for the various kinds of plant 

 nutriment, and adapting them to the proportion of food present in the soil. Phosphoric acid is the 

 rare ingredient of soils and manures, excepting guano and bones, the former of which contains 12 

 and the latter 25 per cent, of tiiis body. Next after this is the azotized matter which forms a small 



