222 AGRICULTURAL REPORT. [Tl412, 413 1 , 413~, 414 



it affords in this respect, even outside of unusually wet seasons. In the ordi- 

 nary condition of soils, about one half of the rain water only reaches the water- 

 courses ; the rest is returned to the atmosphere by evaporation from the soil. 

 This evaporation consumes an enormous amount of heat, which the solar rajs 

 must spend simply to get rid of the surplus water, before they can begin to warm 

 the soil for purposes of vegetation. When, however, this surplus water is 

 carried off by drains, the soil is at once prepared to be warmed, by the first 

 sunshine it may receive. It is very obvious then, why diainage renders soils 

 SO much "earlier," "warmer," and "safer." 



412. Advantages of Drainage in Manured Lands. — There is still another point, 

 which is of considerable importance whenever, in unrttentive soils liquid 

 manures, or such as contain a good deal of easily soluble ingiedients, are em- 

 ployed. It is obvious tliat the higher is the column of soil through which the 

 solution filters, the more effectually will the nutritive ingredients be withdrawn 

 from the latter (1[378, ff.) ; if the soil is very shallow, the solution which has 

 passed through it will still retain a large portion of its ingredients which are 

 then gradually absorbed by the subsoil. If the latter be hard, or drenched 

 with water, the roots of plants will not penetrate it, and thus a large portion of 

 the manure will be lost, when it would all have been deposited within reach of 

 the roots in a deep soil, such :is always results from drainage. 



Such are the chief advantages which drainage secures within the soil, in its 

 relations to the crops ; and their importance, as will appear from the foregoing 

 considerations, is such as to render intelligible in some measuie, the enormous 

 tncrease of productiveness which is so often observed after thorough-drainage. 



413 1 Drainage Prevents Washing. — Among the external effects of this im« 

 provement, the most important perhaps is iis tendency to prevent the washing 

 away of the soil, as well as of manures, by the great diminution of the surface 

 waters which it causes. — The injury produced by the latter does rot consist 

 alone in the absolute removal, in mass, ol the arable Stratum, but also in this, 

 that the finest particles of the soil, upon which the fallow exercises its most 

 energetic action (If 357), are thus carried off" by preference, loaning the fertile 

 bottom soils, greatly at the expense of the uplands. This fine portion of the 

 soil is, of course, retained, when the water, instead of running off* from the 

 surface, is filtered through the soil to the drain, horn which it is.-ares perfectly 

 clear. 



41o 2 - The improvement in the general health of districts where drainage, and 

 particularly underdraining, has become general, is not among the least noticeable 

 advantages which have followed its introduction in numerous cases. 



It could hardly be proper, in this place, to enter into the detail, or to discuss 

 the merits, of the several methods of drainage. I regret that want of space 

 precludes me from appending at the end of this volume, some special considfSa- 

 tioi s of this part ol the sulject, in accordance w ith a des re for in'ormation 

 which 1 have frequently heaid expressed. For a most thorough, lucid, and 

 pleasantly written treatise, embracing the theory as well as the practice of 

 Drainage, 1 refer the reader to the work of Maj H. F. French, lately published.* 



414. Conditions of I'holcctivenessof Soils — We have detinei above two 

 classes of coi ditions requiied to be fulfilled in order to render a soil productive, 

 to-wit : firstly, the proper chemical ionstitution, or the piesenceof the mineral 

 ingiedients required by plants, in an available condition ; secondly, the proper 

 physical constitution, i. e. not being either too light or too heavy, Lut ol that 

 medium character which the planter terms "waim" — an exact definition of 

 which it would be difficult to give, lut which, fortunately, we can abundantly 

 illustrate by examples ficm our favored State. Ihe bcttcm soils of .Noithand 

 Central Mississippi; the table-lands of Korth Marshall and Tippah; the 



* F.um Drainage," by Henry F. French ; New York, Saxton, Barker & Co., 

 1360. 



