IHPROVEMEiXT OF THE SOIL,. 113 



"when employed upon alluvial lands it supersedes the ne- 

 cessity of applying to them other manures ; it is then ad- 

 visable, in overflowings, to retain that mud, and that only, 

 which possesses the greatest power of fertilization. 



When the overflow of a stream commences by inun- 

 dating that portion of land which lies highest up the cur- 

 rent, it spreads with great rapidity over the whole extent 

 of it, furrowing its surface, and carrying beyond it all the 

 most finely divided mud with which it is loaded ; often up- 

 rooting crops and washing away the manures which have 

 been deposited during former overflowings ; and thus im- 

 poverishing instead of enriching the soil. But when the 

 rise of water begins down the current, and the whole tract 

 of land is slowly submerged, till, even to the head, it is 

 under water, the soil receives and retains all the richest 

 and most finely divided mud, as well as the remains of 

 animal and vegetable substances which the stream has in 

 its downward course washed off" from other tracts of coun- 

 try, without any injury being sustained either by the har- 

 vest or the land. In order to give the desired direction to 

 the current, it is only necessary to raise the head of the 

 land, or that part which lies up the stream, tmd to plant 

 the bank with osiers. 



By these means, I have improved and tripled the value 

 of certain islands belonging to me in the river Loire. These 

 islands, which formerly produced but little, and were con- 

 stantly receiving injury from the swellings of the river, are 

 now the most productive portions of my estate, for the cul- 

 tivation of grains and beet roots. 



When sandy or siliceous soils are situated at a distance 

 from a river, or are by the height of the banks placed 

 beyond the reach of an overflow, it is necessary to amelio- 

 rate them by art 3 and this must be done by the addition of 

 fat marl, clay, dung, &c. The amendments must be varied 

 according to the nature and fineness of the sand : calcare- 

 ous sands retain moisture better than siliceous sands. 



I have seen some soils formed of beds of large pebbles, 

 which, without the appearance of mould upon the surface, 

 produced very good crops : the layer of pebbles, which was 

 second from the surface, contained earth enough to enable 

 the plants to take root and flourish. 



Soils of this kind furnish excellent pasture for sheep, as 

 may be observed on the ancient and immense alluvions of 

 the Durance and the Rhone. The herbage upon these if 

 10* 



