f 7 ] 



77. General remarks about Indian Soils. Iron usually 

 occurs in larger proportion than in English soils, in the Indo- 

 Gangetic alluvium 2 to 7 per cent., in the regur 4 to nj per 

 cent., in the Madras red soils 3^ to 10 percent., in true laterite 

 soils 6 to 48 per cent, and in Madras alluviums 5 to 17 per 

 cent. A.umina : The proportion of this substance is also 

 high in Indian soils. In the Indo-Gangetic alluvium 3 to 

 IC >% ; regurs 6 to 14 ; Red soils i \ to 15^ ; laterite 7^ to 14 ; 

 Madras alluvium 6 to 15 in loams, but less in sandy soils. 

 Coffee soils of the Madras Presidency contain as much as 17 

 to 20 per cent, of this constituent. 



MnO : Widely distributed in Indian soils, but the propor- 

 tion is small though quite enpugh for the requirement of 

 plants. Alluvial soils; 'ii to 30 ; regurs "i to 26; Red 

 soils '07 to '2O j laterite soils '06 to '50 ; Madras alluvium 

 03 to '26. 



Lime : Usually as silicate more than as carbonate ; calculat- 

 ed as Oxide, Gangetic alluvium .3 to 2/ ; regur i to 7 "J%\ 

 Madras red soils, laterites and Madras alluvium less than i%. 



An English farmer usually aims at maintaining a fair 

 proportion cf lime in his soil, about i%- This is for the 

 purpose of having a free basic matter to combine with the 

 organic acids as soon as they are formed from the humus 

 and they are continuously being formed. The proportion of 

 humus, however, in English soils is higher and so it is doubt- 

 ful if those Indian soils which contain less than i/ of lime 

 really need to be brought up to the standard aimed at by 

 English farmers. Lime as a plant food is required only in a 

 very minute proportion. The laterite soils which are parti- 

 cularly poor in organic matter are also poor in lime. They 

 would not be benefited by any addition of mere lime. On 

 the whole, it may be said Indian soils are rich in lime. 



MgO More abundant than in English soils : Gangetic 

 alluvium usually over i per cent.; regur i to 3 percent. Red 

 soils | per cent. Laterite soils less. 



