Agricultura I Cheiti istry — Tarn ips. 



531 



space of time half a ton less of bulb, there is an Increase in leaf 

 by 2J tons ; and, as shown in the 3rd column, the proportion of 

 leaf to bulb is more than half as much again. Taking lines 2 

 5ind 5, the addition of ammoniacal salt, as in 5, gives nearly 2 tons 

 less bulb, but nearly 2 tons more leaf, the proportion of leaf to 

 bulb being again increased by one-half. The gross produce is 

 seen therefore to be greater in one of these cases, and as great in 

 the other, under the addition of ammoniacal salts. We have 

 before remarked, however, that whilst at the time of gathering, 

 the crops by mineral manures alone, as in line 1, had probably 

 more than fully arrived at maturity — the leaves having drooped 

 and changed colour — those under rape-cake addition only had 

 but just attained full growth, and those having ammoniacal salts, 

 as in lines 3 and 5, evidently possessed yet unexhausted vitality, 

 especially in No. 5, the case where rape-cake was also supplied. 

 It might be supposed, therefore, that in due course bulbous de- 

 velopment would succeed as the increased leaves drooped. The 

 results of the second gathering, taken when the leaves under am- 

 moniacal salt without rape-cake had considerably fallen (those 

 with it being still vigorous), show this to have been the case to a 

 greater or less degree. A comparison of lines 3 and 4 shows an 

 increase of bulb in three weeks of 7 cwt., at the expense of 19 

 cwt. of fresh weight of leaf. On the other hand, line 6 gives an 

 increase in the same period of 18J cwt. of bulb, at the expense of 

 only 14 cwt. of fresh leaf. Under ammoniacal salts alone there had 

 therefore been an actual depreciation in fresh weight, indicating 

 at least a loss of vitality, though there was probably no real loss 

 of solid matter. Where there was rape-cake also, however, we 

 find an actual gain in gross weight, and we had undoubtedly 

 a vitality and resource of growth still unexhausted. Comparing 

 line 4 with line 1, the latter has still the largest weight of bulb ; 

 and comparing line 6 with line 2, the former is still a ton in 

 advance. Were we to admit, however, that if the crops could 

 have been taken each at the stage of its best yield of hulb, there 

 would have been a slight superiority under the nitrogenous ma- 

 nuring, the quantity yielding the effect in these instances could 

 in no form have been economically obtained, even were there no 

 other objection to its use. 



The effects of an excess of nitrogen in tending to an unprofit- 

 able habit of the plant are further exhibited in page 532 : — 



It is here seen that whilst farm-yard dung, itself containing 

 some nitrogen, and certainly a very full allowance of carbonaceous 

 matter, gives 17 tons of bulb, we have more than 2 tons less bulb 

 when ammoniacal salt is superadded ; but there are at the same 

 time 3 tons more leaf than by dung alone. The 3rd column 

 shows that the actual size of bulb, as well as its acreage produce. 



