ROT IN TIMBER. 



ROTATION OF CROPS, 



grateful to the sheep) ; and, lastly, if some 

 care were taken in supplying them, when feed- 

 ing on watery plants, with a little hay, corn, or 

 oil-cake, that then the destruction caused by 

 this melancholy scourge of the flock-master 

 would be either entirely prevented or very ma- 

 terially reduced. See FLUKE. 



ROT IN TIMBER. It has been noted, that 

 wood saturated with common salt is never sub- 

 ject to this disease. Mr. Bethel has proposed 

 a plan for its prevention, by saturating the 

 wood with coal-tar. Mr. Ryan uses for the 

 same purpose a solution of corrosive subli- 

 mate (muriate of mercury). Sir W. Burnet 

 employs a solution of muriate of lime. See 

 DRY-ROT. 



ROTATION OF CROPS. The order in 

 which different crops are made to succeed each 

 other. It was only towards the middle of the 

 last century, that the importance of a scientific 

 rotation of crops began even to attract the 

 fanner's attention. Previous to that period we 

 search in vain in the works of agricultural au- 

 thors for the slightest notice of such a theme. 

 The writers before those days, as Arthur 

 Young noticed, recited courses of husbandry, 

 good, bad, and execrable, exactly in the same 

 tone as matters not open to praise or censure, 

 and unconnected with any principles that could 

 throw any light on the arrangement of the 

 farm, or its more successful cultivation. And 

 yet it is on this difficult part of the farmer's bu- 

 siness being scientifically pursued, that much 

 of the profits and advantages which he is to 

 derive from his land for a course of years must 

 depend. Arthur Young, the most popular and 

 the most rapid of observers, saw the import- 

 ance of this difficult inquiry in its true light: 

 he correctly enough told the farmers of his day, 

 that whenever very good or very bad husbandry 

 is found on arable land, it is more the result of 

 a right or wrong arrangement of crops than 

 of any other circumstance ; that no district is 

 well cultivated under bad rotations, while it is 

 extremely rare to find any badly cultivated 

 under such as are good. More accurate and 

 more generally diffused observations have long 

 since, however, led the present race of culti- 

 vators to assign to the inquiry its proper value. 

 The importance in fact of the investigation no 

 modern farmer will for a moment doubt. It 

 may not be a useless mode of conducting the 

 research, if we inquire, as we proceed in our 

 proposed examination, into the few yet valu- 

 able lights which chemical and entomological 

 investigations have shed upon this important, 

 yet, from the endless variety of soils and situa- 

 tions, somewhat intricate and laborious theme. 

 In regard to the general principles, as it has 

 been well observed, on which the proper crop- 

 ping of land depends, it is now perfectly under- 

 stood, that some kind of crops deteriorate or 

 exhaust the land to a much greater degree than 

 others ; that some by their capability of being 

 consumed on the farm (though they do exhaust 

 the soil) return, in such consumption by live- 

 stock, as much or perhaps rather more to the 

 soil than they draw from it, during the period 

 of their growth. And again, that other crops, 

 bv admitting of profitable tillage and cleansing 

 Uie land during their growth, aid very much in 



the essential destruction of weeds, insects, &c, 

 and in ameliorating the land for the succeeding 

 crop ; while, on the other hand, different crops, 

 by not permitting such cultivation, and being 

 great exhausters when following in immediate 

 and rapid succession, not only deteriorate the 

 soil, but fill it with weeds and grubs. Hence 

 it follows in practice, that by suitable arrange- 

 ments of these different crops in rotation, most 

 kinds of land may, without lying idle, be con- 

 stantly preserved in a clean and productive 

 condition. In the management of rotations, 

 however, much careful attention and discrimi- 

 nation is requisite in the cultivator, to profit- 

 ably adapt them to the nature of the soil, and 

 the other circumstances under which he is 

 placed. Above all, the farmer must remember, 

 that as different kinds of plants require differ- 

 ent kinds and proportions of nutritious mate- 

 rials to be drawn from the earth for their in~ 

 crease and perfect growth, so also they need 

 different situations and conditions of soil for 

 their most profitable development. 



The farmer, too, is well aware that certain 

 crops never prosper well two or more seasons 

 together in the same land; that they in fact 

 commonly exhaust or "tear out" the soil to 

 such an extent, that every lawyer's clerk is 

 aware of and notices it in some restraining co- 

 venant of " the lease." 



Even the gardener, aided as he is by the 

 most copious supplies of enriching composts, 

 always avoids as much as possible planting a 

 tree where one of the same species has pre- 

 ceded it. 



Now it is of primary importance that we 

 should endeavour to understand, if possible, 

 the cause of this phenomenon. This question, 

 therefore, has long engaged not only the atten- 

 tion of the most sagacious farmers, but of 

 many distinguished chemical philosophers. By 

 these it has been regarded in chiefly two points 

 of view. First, it has been contended, that as 

 each plant has peculiar excretory matters, 

 which it constantly deposits in the soil in 

 \vhich it is placed matters which are found 

 to be particularly noxious to other plants of its 

 own species that in consequence, until these 

 are decomposed and removed from the earth 

 by other plants, or by the gradual effects of de- 

 composition, the same crop cannot advanta- 

 geously prosper in the soil. And in support 

 of this doctrine is adduced the well-known fact, 

 that the excretory matters deposited or diffused 

 through the water in which bulbs or other 

 roots have been cultivated, will not well sup- 

 port other bulbs; yet still that such impure 

 water is found to be more grateful than clear 

 water to vegetables of another species. 



And, again, that certain plants and trees are 

 well known to be excellent and mutua^y fer- 

 tilizing neighbours, a knowledge indeed as 

 old as the days of Rome under her emperors ; 

 for at those periods the Italian farmers com- 

 monly planted the elm as the companion, or 

 husband," as they called it, of the vine : and 

 every farmer is aware, amongst other facts ol 

 a similar nature, that the corn-flower can be 

 found only amongst- his corn crops it is in 

 vain to search for it elsewh?re. The gardener 

 also well knows, that it is almost useless to 



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