Agricultural Chemistry — Turnips. 



543 



of growth, it may in fact bespeak the worst manuring condition, 

 all other circumstances being equal. It is evident then, that, 

 even supposing the percentage of dry matter to be an uncondi- 

 tional measure of the feeding value of any particular specimens, 

 no comparison could be drawn respecting the efficiency of the 

 manures by which they were grown, unless every olher condition, 

 whether of season, soil, maturity or variety, were considered in their 

 influence ; and then, indeed, the effects of the manures may be 

 due to a forcing rather than to a supporting power. We shall 

 have further proof, however, that the amount of water existing in 

 the turnip depends upon the proportion of circulatory to the more 

 fixed matter, and that as the plant matures that of the former di- 

 minishes and that of the latter increases ; and it will also be seen 

 that equal weights of dry matter may differ very greatly in pro- 

 bable nutritive value. 



Before leaving the results of the table, we may observe that by 

 this series of nearly 100 different manures, the utmost variation in 

 the proportion of dry matter in the Norfolk white-turnip bulb is, 

 after an equal period of time, 2*65, or about 2J per cent., not- 

 withstanding that there was a vast difference in the stage of 

 maturity of the plants ; and it is thought that if the specimens 

 could have been taken each at the point of its fullest growth, the 

 variation strictly dependent on manures would have been much 

 less. The highest percentage of dry matter in the entire series 

 is 9*3, — all the rest are below 9, more than half below 8, and 

 several below 7 ; the limit of difference, even under the actual 

 circumstances, is, however, in by far the larger number of cases 

 within 1 per cent. Boussingault gives 7*58 per cent., which 

 agrees pretty well with our determinations, the mean of which is 

 7 • 83 ; other observers having found a range in the proportion of dry 

 matter of the turnip-bulb from this amount to nearly double, have 

 attributed much of the variation to the conditions of manuring ; 

 but the foregoing facts, in conjunction with those we shall now 

 state, will show that no judgment of the effects of manures in this 

 respect can be formed unless the experiments are made with the 

 same variety of the plant. 



The specimens here referred to were grown in different fields, 

 and by different manures, and several of them in the ordinary 

 course of the farm. The 90 lots of experimental Norfolk whites 

 give a number for the mean percentage of dry matter identical 

 with that found under farm-yard dung, and their extreme varia- 

 tion is 2 • 65. The two specimens of green common turnips show 

 the same amount of dry matter with a difference of manuring. 

 The various swedes again differ considerably from one another^ 

 yet in a greater degree from the common turnips. The extreme 

 variation in the entire series quoted is from 6*65 in the Norfolk 



