SOILS — FERTILIZERS. 525 



Proijortions of lime to magnesia in soil, R. R. Snowden {Rural Calif ornian, 

 &.i ( li)lU), No. 12, pp. 35S-360). — Investigations are briefly reported in this article 

 which led the author to believe that many cases of malnutrition, particularly 

 incipient chlorosis or mottled leaf in orange and lemon trees, can be traced 

 to an excessive proportion of magnesia to lime in the soil. 



Analyses of sick and healthy leaves showed that the potash had increased in 

 the sick leaves to more than two and one-half times that in the healthy leaves 

 and the phosphoric acid to more than eleven and one-half times as much, while 

 there had been a marked decline in the percentage of lime. 



Examinations of a number of soils on which sick and healthy trees were 

 growing showed that when the ijercentage of lime in the soil was less than 

 twice that of the magnesia there was derangement of nutrition in orange trees. 

 Lemon trees, however, appeared to be more tolerant of this condition, and it 

 is thought that this explains why mottled leaf is far more prevalent with 

 oranges than with lemons. With lemons the limit of safety appears to lie 

 somewhere between 0.67 and 0.84 part of lime to one of magnesia. 



Examinations of soils from a large number of citrus-growing districts showed 

 that unfavorable proportions of lime to magnesia widely prevailed. Of 32 

 samples of soil examined only 13 contained the required proportion of lime 

 from the standpoint of orange growing. 



Attention is called to the fact that lime is more rapidly depleted than mag- 

 nesia by the processes of nutrition, and methods of overcoming the unfavorable 

 conditions thus brought about are suggested. 



Laboratory studies of the influence of magnesia on the solubility of lime 

 salts were made in which mixtures of equal amounts of magnesium and cal- 

 cium carbonates and of magnesium and calcium sulphates, and a soil contain- 

 ing twice as much magnesia as lime, were used. It was found that in the case 

 of the carbonates 23 per cent of the magnesia and a mere trace of the lime were 

 dissolved ; in the case of the sulphates IS per cent of the magnesia and 7 per 

 cent of the lime were dissolved; and in the case of the soil the water extract 

 contained 19 times as much magnesia as lime. " The trees growing in this 

 soil, unable to assimilate sufllcient lime to supply their needs, absorbed the 

 larger amount of potash noted in the yellow leaves to supply the deficiency 

 of bases, the salts of potash being indei>endent of a condition of acidity for 

 their solution." 



Improving alkaline lands, T. B. Robertson (Jour. Dept. Agr. So. Aust., 13 

 {1910), No. 12, pp. 1046-1050).— The author briefly reviews work by Osterhout 

 on the antagonistic action of different salts in nutrient solutions (E. S. R., 19, 

 p. 1129), and suggests that the results of these investigations may find a 

 rational application in methods of correcting the alkalinity of soils, that un- 

 productive soils containing an excess of magnesia may be improved, and that 

 a variety of soils of low fertility may be made productive by a study of the 

 nature and amounts of mineral salts in the soil water and by a judicious addi- 

 tion of other salts. 



A short bibliography of the subject is given. 



On the agricultural value and the fertilizer requirements of the Norr- 

 botten marsh soils, P. Hellstrom {K. Landthr. Akad. Handl. och Tidskr., 49 

 {1910), No. 5, pp. 372-407, pis. 16).— This article gives a condensed report of 

 investigations and trials relative to the agricultural value of the Norrbotten 

 marsh lands that have been conducted during late years at the chemical plant 

 biological station at Lulea. 



The results obtained show that the marshes can by proper treatment be 

 brought up to as high a productive capacity as mineral soils for growing both 



