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III. The Rotation of One Principle. 
Boussaingault, Payen and the majority of French agriculturists estimate the value of 
manures by the amount of azote they contain; and there is not, for general purposes, a more useful 
test. Therefore the great object of manuring is with them the application of azote to the soil, 
and the great — if not the sole — principle in rotations the economy of this body. As some crops 
gain azote from the air, as clovers and grasses, these serve an important purpose in such a plan by 
concurring with manure in supplying food for the cerealia and such crops as exhaust the soil. 
According to Boussaingault we should therefore, in a system of rotation, introduce crops in such 
order that after the manure a highly exhausting plant as wheat may come and this he succeeded 
by others of less affinity for nitrogen, and again by those which draw their supplies from the air and 
are the ameliorating crops of this class of agriculturists. The soil now recruited by clover, lucern, 
grass, etc., will hear another azotized crop and the system is at an end. 
There is something charmingly simple and plausible in this rotation of one principle, and its 
author has done much to establish it by appeal to practice. It is, moreover, identical with the 
natural rotation observed in new lands, and thus appears to challenge opposition. But there is a 
capital difference between any artificial and the natural rotation, in this particular, that in the latter case 
the plants die on the spot and are not removed hence, and whatever exhaustion arises from removing 
the crop is arrested. Our corn, wheat and oats not only draw azote from the soil but other bodies, 
and these are entirely withdrawn from the spot, whilst only the azote is removed by the natural 
succession of plants. Of the inorganic or saline matters much more is often withdrawn, that of 
azote; hence, whilst the new land is exhausted of but one element of fertility, the cultivated field 
loses more. 
The greatest objection to this view of rotation is its opposition to experience, for it will be seen 
that a system, perfectly proper, according to this theory of one principle is inadmissible in ordinary 
practice. No one who is acquainted with the subject would expect much from the following succes¬ 
sion : manure, corn, oats, beans, buckwheat, clover, wheat—yet it is a system in which the azotized 
matter of the manure would be well economized and the soil rather enriched in this respect. But 
the farmer knows that such a succession of seed crops would soon render his land valueless, 
whether organic matter were accumulated or otherwise. The one principle rotation is not, there¬ 
fore, acceptable to the understanding of theoretical nor to the experience of practical agriculturists. 
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