PLATE I. 



Fig. 1, — Sorghum grown in soil with a high content of NO3 

 and Mn. 



(1) Untreated. 



(2) Limed. 



(3) Leached. 



(4) Leached and, NO3 equivalent returned as NaNOo. 



Fig. 2. — Sorghum grown in water extract of soil with a high 

 content of NO3 and Mn. 



( 1 ) Distilled water. 



( 2 ) Soil extract diluted 50 per cent, precipitated witli 

 NaOH. 



( 3 ) Soil extract diluted 75 per cent, precipitated with 

 NaOH. 



( 4 ) Distillate of soil extract diluted 50 per cent. 



( 5 ) Non-volatile part of extract diluted 50 per cent. 



( G ) Soil extract treated with carbon black, diluted 50 per 

 cent. 



( 7 ) Soil extract evaporated, ignited, dissolved, diluted 50 

 per cent. 



( 8 ) Distilled water treated with carbon black. 



( 9 ) Soil extract diluted 50 per cent. 



(10) Soil extract diluted 75 per cent. 



