Tf3V>4. :-$i*-'>. •'.♦•. 3i»7J ROTATION — ANALYSI*-OF SOILS. 217-" 



is the rationale of tho good effect of the Rotation of Crops. — But rotation- alone, 

 as these considerations show, is no', in reality an improvement of the soil ; on 

 the contrary, it is but a system itic method of exk tasting it to the best advantage. 

 Eventually", it will cease to be effective ; and thereafter, crops will be dependent 

 altogether upon Manures — "No manure, no crops " 



39i. Or.lerof Ifot'ttion — Analyses. — Experience has, in a great many of the 

 crops long known, demonstrated the proper order of succession for certain kinds 

 of soil. The sime will not, however, always hold good in reference to other 

 soils, of a dissimilar, or unusual constitution ; and from a disregard, or want of 

 knowledge of this fact, many disappointments, and a great diversity of opinions 

 on this subject has arisen. In many cases of this kind, comparative analyses 

 of the soils as well as of the crops in question, have plainly shown, not only the 

 cause ol the anomaly observed, but also the remedy, by indicating the proper 

 order to be followed. 



With respect to crops of modern date, Chemical Analysis has done the same 

 thing, or can do it where it is not alrea ly done. The crops most important to 

 the Southern States, are stdl in want of a thorough examination in this respect ; 

 to give which 1 consider, not only as one of the legitimate, but also, as one of 

 the most important oljjects of the Agricultural Survey. 



395. Analyses of Soils, Crops and Manukbs — Analysis teaches us, what 

 are the kinds and respective quantities of the ingredients contained in crops, soils 

 and manures. It teaches us, therefore, which of the latter two will be best 

 calculated to promote the successful culture of the former ; a knowledge to 

 obtain which by mere experimenting, would requite a disproportionate amount 

 of time and labor. It has already been stated, that the al sence of a single one 

 of the ingredients necessary lor the growth of a plant, renders unavailing the 

 presence of all the rest* Unless we are taught, by analyst, which is the 

 ingredient — or ingredients — of which there is a deficiency, we shall be compelled, 

 in order to be safe, to add all of them, at great and unnecessary expense ; for 

 it will be of no practical advantage" to have added an additional supply of those 

 of which there was no lack. 



39b\ Analyses of Soils. — The importance of reliable analyses of crops, soils 

 and manures, is, therefore, obvious enough. Yet the mere presence of any 

 useful ingredient in a soil, or manure, as demonstrated by analysis, does not yet 

 assure us that it is present in an available condition, so as to be ready for 

 absorption by the plant ; for the agents which the chemist uses in the laboratory, 

 are much more powerful than those placed at the command of vegetables by 

 nature. In the course of a few hours or days, we can abstract from the soil all 

 those ingredients which, in the ordinary course of fallowing pursued by natute, 

 it would have required centuries to bring into action t1T3(38j ; thus far, there- 

 fore, mere ultimate analyses are not a direct indication of the producing powers 

 of the soil. 



397. This consideration becomes of most serious moment, where the rocks 

 from which the soils are originally derived are in close proximitv , so that a large 

 amount of undecom posed material miy be supposed to be very unevenly, diffused 

 throughout the soil. It will be less so, when the minerals constituting the several 

 soils have been transported to a great distance and i ecome thoroughly inter- 

 mingled and comminuted ; as is mostly the ease in Mississippi. 



Yet still, the determination ot the available portion of mineral nutriment 

 contained in the several soils, is of great importance, and it is intended that it 

 shall be made in every case of soil-analysis, so far as the means we possess of 

 imitating the operations of nature in this instance, will allow ; want of suitable 

 arrangements alone having prevented their being made as yet, with reference to 

 the analyses thus far executed. Yet even without these detei ruinations, the 

 soil-analyses afford us a safe basis for our operations. For since, in nil the soils 

 of Mississippi, the component minerals (except quartz) are in a very finely 

 comminuted condition, we know that when ultimate analysis shows the 



