354 On Pari/if/ and Burninfj. 



and burning, are disseminated throughout a large mass of soil, 

 and therefore of comparatively little value to crops which, like 

 turnips, remain on the land but four or five montlis, and which 

 are not provided with the food-searching apparatus which is 

 presented to us in the long fibrous roots of wheat, clover, and 

 various other plants. During the winter, these crops, prevented 

 by the cold from making much progress in an upward direction, 

 extend their roots downward, thereby establishing by degrees 

 an apparatus which is ready to supply the growing plant with 

 abundance of mineral food as soon as the warmer season of the 

 year pushes on the young and fairly established plant. I'his, no 

 doubt, is the reason why the direct supply of mineral substances 

 in most soils produces liardly any effect upon wheat: quite tiie 

 reverse takes place when root-crops are manured with minerals. 

 It may be shown that a soil contains possibly 1000 times as much 

 phosphate of lime as is contained in the ashes of a lieavy crop of 

 roots, for which reason a good dressing with superphosphate or 

 bone-dust in the eye of the speculative chemist may appear waste- 

 ful and contrary to every chemical principle ; and yet it can be 

 proved that such a diesslng must do good to turnips. ^\ liat does 

 the young turnip gain, if tliere is plenty of phosphate of lime 

 In the soil and the plant cannot reach it; or what benefit is a 

 superabundance of j)hosphate of lime spread all over the field, 

 when the turnip crop is stopped in its growth by the cold weather 

 in autumn, before the crop lias had time to collect the dissemi- 

 nated phosphates in a sufficient quantity to enable it to form 

 large bulbs? Tlie shorter the period of vegetation the greater 

 the necessity of a superabundant supply of mineral matters in that 

 portion of the soil wliich is within reach of the })lant. Hence the 

 direct supply of bone-dust or superphosphate to a portion of the 

 soil produces such marvellous effects ; thoroughly incorporated 

 with the whole mass of soil, it would do much less, if any good. 

 Hence also the great value of the ashes produced on paring and 

 burning. The roots of the plants which furnish these ashes pene- 

 trate the soil to a great deptli, and having ransacked tlie soil, so to 

 speak, In every direction, anil sifted out of it the phosphate of 

 lime, potash, &c., which constitute but a very small proportion of 

 the whole mass of soil and subsoil, leave these and other important 

 mineral fertilizers, on burning, in a small compass. Incorporated 

 with a portion of the surface soil, they superabundantly enrich it 

 with those fertilizing constituents, which experience has shown 

 to be especially valuable for root-crops. 



If the roots, &c., of former crops exercise such a beneficial 

 efifett, it may be said, why not let them become gradually de- 

 composed ? By doing this, would the farmer not realize all t!ie 

 advantages of a concentration of mineral food in the surface soil. 



