The Wohurn Pot-Culture E.vperiments, 1910-11-12. 321 



(b) The influence of Zinc Salts on Wheat. 



Already in 1909 experiments were begun with salts of zinc, 

 the oxide, chloiide, sulphate, and carljonate being tried, and 

 each in quantity supplying •()A per cent, of the metal zinc in 

 the soil used. Used at this rate it was found that the zinc salts 

 were, one and all, detrimental to the crop, the injury being the 

 more marked with the soluble salts (chloride and sulphate). 

 This work is recorded in Journal R.A.S.E., Vol. 71, 1910, 

 page 345. 



1. Zmc Salts, 1910. 



In 1910 the experiments with zinc were continued, the 

 same salts (oxide, chloride, sulphate, and carbonate) being used, 

 with the addition of the phosphate and nitrate. Also the 

 amount of zinc supplied was in each case only "02 per cent, in 

 place of the '04 per cent, used in 1909. 



The general details of the arrangements were quite similar 

 to those just recorded in the case of the lithium experiments, 

 so that they need not be repeated. 



There was practically no influence on the period of incu- 

 bation of the seed, thus forming a contrast to the lithium salts 

 which were then also being tried, and this, although the zinc 

 salts were being used in much greater concentration than the 

 lithium salts, tip to the end of April no clear differences could 

 be seen between any of the crops, and none then showed any 

 signs of toxic effect. On the whole, the oxide and carbonate 

 plants looked about the best, and with the more soluble salts — 

 chloride, sulphate and nitrate — the straw seemed to be affected 

 as regards length. Some while later, the nitrate plants began 

 to develop more growth and to show a broad dark-coloured flag ; 

 this was accompanied l)y a marked increase in the tillering, so 

 that when, eventually, measurements, &c., of the crops were 

 taken, though the zinc nitrate was found to have reduced the 

 length of the straw, it yet gave more stalks and a greater length 

 of ear than any other lot. There was nothing particular to 

 remark at harvest-time between the applications as regards 

 length of straw and ear, except in respect of the nitrate, which 

 gave only 77 per cent, of the length of straw of the " control " 

 set, though the length of ear was 106-9 as against 100. When 

 the corn came to l)e threshed and weighed, the comparative 

 results were : — 



No. of 

 Ears 

 No treatment . l(((i 



Zinc oxiile 

 Zinc carbonate 

 Zinc chloride 

 Zinc sulphate 

 Zinc nitrate 

 Zinc phosphate 



112 

 132 

 13(3 

 152 

 184 

 9« 



VOL. 73. u 



