506 Agricultural Chemistry —Ttirnips. 



those having manures only mineral indicate a growth almost three- 

 fold in the same space of time, whilst the actual acreage amount 

 of produce is in these cases very nearly as great as in any of the 

 series ; indeed, mineral manures alone have nearly trebled the 

 unaided produce of the soil and season. 



These results might almost lead us to question the importance 

 of organic manuring for the turnip crop, and to assume that a 

 deficiency in mineral matters was the source of impoverishment in 

 the case of the soil selected for experiment; but as we proceed 

 it will be seen that, however marked may have been the effect of 

 mineral matters in developing the powers of growth of the plant, 

 as long as a sufficiency of organic food remained, yet a point of 

 exhaustion was arrived at when, by a less amount of mineral 

 matter, if in conjunction with organic supply (especially such as 

 could yield carbon to the plants), the rapidity of hulb formation 

 was materially enhanced. 



Before leaving these results it is as well to observe, that not- 

 withstanding the large amount of potass required by the turnip, 

 the direct supply of that alkali did not give a produce superior 

 to that by superphosphate of lime. We shall have occasion to 

 recur to the question, whether part of the effect of the latter 

 manure is not due to its liberation in the soil of alkalis not other- 

 wise available to the plant. All we wish to call attention to at 

 the present is, that there was an abundant amount of alkalis in 

 this corn-exhausted soil, which could be rendered serviceable 

 under suitable management. 



The next quotations which we shall make from the table (page 

 503) will serve to illustrate the effect of the artificial supply of 

 matter for organic formations, aided by certain mineral agency 

 and constituency : — 



Selected Results. 



Plot 

 No. 



Description, of Manures. 



Average 

 wei^iht 

 ofBulbs. 



Number 

 of Plants 

 per Acre. 



9 

 10 

 12 



13 



14 



15 



19 



20 



2^ cwts. superphosphate of lime, 3f cwts. rape-cake 



2J cwts. superphosphate of lime, 2 cwts, rape-cake, 20 lbs. 



sulphate of ammonia t . . 



1 J cwt. superphosphate of lime, 1 cwt. rape-cake, 40 lbs. 



sulphate of ammonia 



IJ cwt. superphosphate of lime, 3| cwts. rape-cake, 10 lbs. 



sulphate of ammonia 



3f cwts. superphosphate of lime, 2f cwts. rape-cake, 20 lbs. 



sulphate of ammonia • 



3^ cwts. superphosphate of lime, 84 lbs. phosphate, magnesia, 

 75 lbs. phosphate of potass, 30 lbs. sulphate of ammonia . 



3i cwts. superphosphate of lime, 

 sulphate of ammonia 



cwt. rape-cake, 16 lbs. 



1-69 

 1-52 



1-58 



1-48 

 1-42 

 1-23 

 1-75 

 1-49 

 1-58 



16,096 

 15, -295 

 18,009 



17,112 



16,617 



17,790 



15,088 



19,113 



16,916 



