INJURIOUS EFFECT OF SULFATE OF AMMONIA. 129 



the amount taken up by the plant. While some manganese is carried 

 into the tops, most of it remains in the roots. 



In order to determine whether calcium carbonate or sulfate had any 

 beneficial action in more dilute solutions of manganese a second experi- 

 ment was undertaken. In this series 10 parts and 20 parts of manganese 

 in a million parts of nutrient solution were, respectively, compared with 

 the standard and with equal amounts of manganese supplemented by 

 calcium carbonate and by calcium sulfate. 



At the end of three weeks all the seedlings except those in the standard 

 solution showed chlorosis by the hght green or yellowish color of the 

 leaves. The more dilute manganese still had a detrimental effect on the 

 clover plants, but not so marked as in the previous experiments with 

 higher concentrations. Neither of the calcium compounds exerted any 

 beneficial effects, but as in the first experiment seemed, if anytliing, to 

 increase the injury. 



A third series of cultures was conducted during the winter in the green- 

 house, and concentrations of from 10 parts to 40 parts of manganese per 

 milHon of nutrient solution were again tried with and without calcium 

 carbonate added to the solution. Much cloudy weather caused an in- 

 ferior growth of the clover plants, but the experiment was continued four 

 weeks, and at the end there was the same chlorosis of the leaves when 

 manganese was present. Again, calcium carbonate failed to prevent the 

 chlorosis in the presence of manganese, and instead apparently increased it. 



Masoni,^ PugUese^ and Aso^ have found that iron salts seem to counter- 

 act the toxicity of manganese. In order to confirm their conclusions one 

 series of experiments was undertaken using a combination of these two 

 salts, another series using manganese plus aluminium salt, and still another 

 series using ii-on and aluminium together. 



To the standard nutrient solution were added 20 parts of manganese 

 and 2 different quantities of aluminium, 21.6 parts and 43 parts, respec- 

 tively, per milhon of solution, with and without calcium carbonate. A 

 similar series was prepai'ed containing 22 and 44 parts of iron per million, 

 respectively. 



All the solutions containing iron produced seedlings with darker color 

 than the rest. The roots in the solutions containing aluminium or iron 

 became stunted in appearance whether calcium carbonate was present or 

 not. Manganese and aluminium or iron had no apparent antagonistic 

 effects when present together in a nutrient solution. 



This toxicity with calcium carbonate is unlike the results reported by 

 McCool,^ who found that calcium chloride would counteract the toxicity 

 of manganese to a marked extent. This may be due to the difference in 

 the solutions and seedlings used, as he used manganese chloride, calcium 

 cliloride and Canada field peas. 



1 Staz. Sper. Agr. Ital. 44 (1911), p. 85; Abs. E. S. R. 26. 



! Atti R 1st Incoragg. Napoli 6 ser. 65 (1913), p. 289; Abs. Chem. Abs. 9, p. 641. 



3 Bui. Agr. College, Tokyo, V. p. 177. 



« Cornell Agr. Exp. Sta. Memoir No. 2 (1913). 



