LIMING OF SOILS FROM A PHYSIOLOGICAL STANDPUINT. 29 
For one hectare of vineyard there would be annually required 45.48 
kilograms of lime and 16.92 kilograms of magnesia, or nearly two and 
two-thirds times as much lime as magnesia.’ It happens, however, that 
in the soils of the vineyards often a very different ratio prevails, and 
especially that their lime content runs very high. It was observed in 
France that soils too rich in lime (18 per cent and over) produced the 
**vyellows” in the vines, and that spraying the leaves with a diluted 
(1 per cent) solution of ferrous sulphate cured the disease.” The high. 
content of calcium carbonate of the soil probably neutralized the acid 
secretions of the roots, and thus frustrated the absorption of the iron 
compounds from the soil. Neither magnesium nor ammonium sul- 
phate were observed to have any curative effect in these cases.* The 
question whether a great excess of lime can under other conditions 
interfere with the absorption of the iron deserves further attention. 
Another cause of the ** yellows” appears to be sometimes a lack of 
lime in the soil, since in certain districts of France, les Pouilles and 
VY Aude, slacked lime has been applied for the last fifty years to the 
affected foilage with much success, as Meunier, Cachard, and Gos 
report. * 
Further causes of the ** yellows” may be a Jack of magnesia or of 
phosphoric acid or of nitrogen. Stohman’ mentions that plants culti- 
vated for some time without any supply of nitrogen compounds lose 
the normal green of the leaves, and that a supply of ammonium 
nitrate will remedy the evil. Knop® observed that an excess of cal- 
cium nitrate, as well as of magnesium nitrate, in culture solutions, can 
cause yellowing of the leaves, and that in such cases an addition of 
ammonium sulphate had a curative effect. Stohman, however, does 
not fully agree, since he was unable to cure such cases by ammonium 
nitrate. 
The writer showed years ago that a kind of ** yellows” is produced 
by a lack of phosphate.‘ Algz turned gradually yellow in culture 
solutions in which phosphoric acid was absent, and the addition of a 
trace of secondary sodium phosphate sufficed to restore the normal 
green color. 
In regard to the dependence of full development upon the ratio of 
lime and magnesia, an interesting observation on the chestnut tree 
may be mentioned. Grandeau and Fliche* analyzed leaves and 
oranches of a tree in normal healthy development and of another of 
?W olifi’s Tables, II, p. 63. 
? Jahrbuch der Deutschen Landw. Gesellschaft, Vol. VIII, p. 437. 
*The French grape vines are much more susceptible to the “ yellows”’ after being 
graited with the American vine than they are before, as Liidecke mentions. The 
varieties Jaques and Riparia appear to be unable to thrive on soil with more than 18 
per cent of lime, but Rupestric is capable of it. 
*Le Progrés Agricole et Viticole, 1899, No. 31. 
°Chem. Centralbl., 1861, p. 597. ®Ibid., p. 476. 
‘Botan. Centralbl., 1891, p. 371. © Wolff’s Tables, II, p. 102. 
