258 BENEFIT OP CLOVER. 



selves of and assimilate carbon, hydrogen, and oxygen, all drawn 

 from""water and the air only \ and also, that in addition to these ele- 

 ments, the leguminous plants, and these only, drew azote from the air, 

 assimilated or fixed it in their bodies, and thus could give it to the 

 soil as manure. When other plants contain azote, and give it to 

 the soil as manure, they had derived the whole supply previously 

 from the soil, and therefore there was no gain in regard to that 

 richest element. But the leguminous plants, deriving part of their 

 azote from the atmosphere, give so much to the soil, if used as 

 manure, more than the soil had before furnished. This peculiar 

 power of leguminous plants is an important cause of their well- 

 known peculiar value as manuring crops. 



It has long been a received and unquestioned opinion among in- 

 telligent farmers, that the growth of clover, and other leguminous 

 crops, drew away from the soil less of the fertilizing principles, and 

 returned to it more, than any others. This opinion prevailed in 

 districts where most of the product of clover was usually removed 

 from the fields, as well as in other places where the clover was 

 mostly left on the ground, to be ploughed under as manure. In 

 Lower Virginia, wherever improvements by calcareous manures and 

 by clover have correctly gone together, and however the rotations 

 of crops may diifer in other respects, there is one part of the courses 

 of crops generally alike, viz., the succession of 1st, Indian corn ; 

 2d. wheat ; 3d, clover ; and 4th, wheat. On some farms (of best 

 soil, which only can bear such severe cropping), this is the whole 

 course constituting a four-shift rotation. On others, and more 

 generally, a fifth year is added, of rest, or at most of pasturage 

 only, and interposed between the fourth crop, wheat on clover, and 

 the subsequent recurrence of the first crop in the series, Indian 

 corn. In either case, it is generally believed that the product of 

 the second crop of wheat, sown upon clover turned under as manure, 

 is usually about double that of the first crop of wheat following 

 corn, though the immediately preceding corn crop had received all 

 the prepared putrescent manure given. This great difference of 

 production, however, is not altogether due to the clover manure 

 for the second, or " fallow" crop of wheat, but partly to the cir- 

 cumstance of the first crop of wheat having followed another grain 

 crop, which is a vile succession, and must always lessen the second 

 or immediately succeeding crop more than in proportion to the then 

 actual productive powers of the land. In my own practice, as in 

 general of others, there have been no separate measurements of 

 these two nearest crops of wheat, or any parts thereof, from the 

 same land. But the same estimate of difference has been made 

 upon merely general observation, viz., that the wheat after clover 

 was usually double as much as the previous wheat after corn on 

 the same field. My own putrescent manure, frcm stable and stock- 



