204 BOARD OF AGRICULTURE. 



matter in the table is considered free from that variable amount of 

 water which is always present in the plant, unless it has been 

 dried at a temperature of 212°. In the case of barley, we have 

 about half as much as in rye — 1515 lbs.; in oats, 2200 lbs.; in 

 red clover, 6580 lbs.; in buckwheat, 1630 lbs., and so on. You 

 see that in the amount of matter remaining 1 in the soil, the clover 

 crop far surpasses any other. If it were a fact that the organic 

 vegetable matter of one crop remaining in the soil, supplies the 

 food for the following crop, you see that what remains in the soil 

 from a good clover crop would furnish the material for about three 

 oat or wheat crops. It is not the fact, that the vegetable matter 

 from one crop acts as such directly to support the succeeding 

 crop ; but it is a fact that some of the ingredients of the vegetable 

 matter are of use to the succeeding crop, and in some places must 

 be supplied, in order that the succeeding crop may grow. That 

 is especially true of nitrogen. We have in the clover field a resi- 

 due of 180 lbs. of nitrogen ; in rye, we have 62 lbs.; in oats, 25 

 lbs.; in some other crops we have a larger quantity ; you see how 

 the figures run. (p. 194.) This nitrogen came partly from the 

 atmosphere by the foliage, and partly from the soil taken up by 

 the roots. The clover residues contain three times as much nitro- 

 gen as those of rye and 7 to 8 times as much as those of wheat, 

 barley, or oats. We have 246 lbs. of lime remaining in the residue 

 of clover — three times as much as in that of any other crop. 

 This, of course, came from the soil. All these shallow-rooted 

 plants, when they succeed clover, find ready to their hand, in the 

 upper eight or ten inches of the soil, material brought up by the 

 previous clover crop from twice that depth, or more. The clover 

 not only furnishes to the succeeding crop the mineral matters that 

 were in the upper portion of the soil, but it takes them up from a 

 depth where they would not be directly accessible to other plants, 

 and puts them where they are wanted. The clover plant leaves 

 in the surface soil, as the table shows, a much larger quantity of 

 all those materials than any other crop. The only apparent ex- 

 ception is that of soda, and soda is a substance which is not, as 

 the best information we have upon the subject tends to show, 

 essential to any cultivated plant. We have of magnesia, 46 lbs. 

 in clover, against 14 in rye. Of potash, 77 lbs. in clover, against 

 30 lbs. in rye. Of sulphuric acid, we have 24 lbs. in the case of 

 clover, against 12 in the case of rye. Of phosphoric acid, which 

 is, on the whole, the most precious mineral substance in the soil, 



