41 



Series 1 received no treatment; series 2 was limed; 

 series 3 and 4 were thoroughly leached. Alter leach- 

 ing, series 3 received no further treatment, while se- 

 ries 4 received nitrate of soda sufficient to replace the 

 nitrate nitrogen removed hv the leaching. As soon as 

 the soil from the pots had dried sufficiently to permit 

 l)lanting, the several series were planted to sorghum. 

 When the plants were about 2 inches high, the number 

 was reduced to 8 plants per pot. The sorghum was 

 harvested when some of the plants were in head, and 

 the green weights taken. One pot of each series is 

 shown in Plate I, fig. 1, and the average weights of the 

 crops are given in Table I. 



Table I. — The Effect of leaching, lime, etc., on the 



Growth of Sorghum in Acid Soil with a High 



Nitrate Content. 



TREATMENT 



Green weight 



of sorghum: 



grams 



Checks, no treatment | 55.5 



Limed, 18 gr. per pot I 263.5 



Leached I 75.5 



Leached, NO., equivalent returned as NaNOg | 278.0 



The plants in the check pots showed a very nn- 

 healthy color as soon as they came up. After being 

 thinned nearly all the plants in the check pots died. 

 For about 5 or 6 weeks the surviving plants retained 

 the unhealthy color, the tips and margins of the leaves 

 showing the injury most clearly. I^ater, these plants 

 seemed to overcome the initial injury, and made a 

 satisfactory growth. The plants in the limed pots 

 made a rather poor growth for a short time, after which 

 they grew rapidly. In the leached pots the plants 

 made a normal grow^th, but appeared to lack nitrogen. 

 The fourth series which had been leached and treated 

 with sodium nitrate in sufficient quantity to return the 

 nitrate nitrogen removed, made a verj' satisfactory 

 growth throughout. 



This work w^as in part repeated, using small jars of 

 about 2 pounds capacity as the containers. Similar 

 soil wdth a high nitrate content was used. The un- 

 leached soil proved to be so toxic that all plants died 

 after a few days. The duplicate jars were replanted, 

 and again all but one plant died. The soil that had 

 been thoroughly leached produced normal plants, both 

 root and top. Liming this soil in a large measure re- 



