ANCIENT ALLUVIAL OR LATTER DRIFT SOILS. 233 



judging from the effects as manure, it seems probable that some 

 phosphate of lime is also present. By these auxiliary ingredients, 

 added to the main source of fertility, the calx of the manuring 

 earth, the vigour and luxuriance of clover is peculiarly promoted 

 beyond any effect of calxing alone known elsewhere and the 

 succeeding wheat crop is also increased in proportion to the clover- 

 manure grown and turned under to prepare for the wheat. 



Some small portions of the Pamunkey flats are of close and im- 

 permeable pale yellowish clay, and the value much the less fbr this 

 objectionable quality. But most of such lands are of light sandy 

 loam, and some very sandy. Some of the sands are of mulatto 

 soil, and some gray, and even approaching to acid character. No 

 red clay soil, or sub-soil, is there known. 



It has been deemed proper to speak thus fully of these neutral 

 soils, and their improvement by calxing, because the circumstances 

 serve most clearly to establish the opinion stated formerly (in the 

 edition of 1842), that calcareous manures must possess some other 

 and important fertilizing action, besides the several kinds before 

 asserted (in Chap. VIII.). Of these several powers, neutral soils 

 did not require, and therefore could not profit by that of neutraliz- 

 ing acids ; nor of altering the texture, absorbency, &c., of the soil. 

 Such soil had already been provided by natural constitution with 

 enough lime for these purposes. Therefore, the only other fertiliz- 

 ing property there claimed, in advance of experience, for calcareous 

 earth, that of combining with, preserving, and fixing putrescent 

 manures in soils, was all that could be counted upon to improve 

 neutral soils. But this slow and merely conservative action, how- 

 ever valuable for improvement, could not possibly be the sole cause 

 of the great and progressively increasing production of neutral 

 soils, which was manifest within a few years after their being 

 calxed ; and other and important causes had evidently been operat- 

 ing. And although the circumstances of neutral soils led more 

 immediately to this conclusion, those of the acid soils also con- 

 curred. As was intimated in former editions, on all soils and crops 

 which were improved by calcareous manures, though the expe- 

 rienced effects were strictly in accordance with the theory of their 

 operation, they seemed in measure and amount to surpass their 

 supposed causes. I will now proceed to set forth other auxiliary 

 causes of fertilizing action and power of calcareous earth, or lime 

 salts generally, in soils ; which causes have been suggested by or 

 deduced from the more recent lights furnished by the progress of 

 the science of agricultural chemistry, and in part are the results 

 of my own later observations or experience. The most important 

 of these additional powers or operations of lime in soil are the 

 following : 



20* 



