[ 74 ] 



of Pratapgarh. Speaking generally Indian soils contain less 

 than -i per cent, of N. The Gangetic alluvium contains only 

 05 per cent, (a little more or a little less). In the Madras 

 alluvium the proportion is the same or a little higher. The 

 Regurs and Red soils usually contain less than -05 per cent. 

 Laterite soils contain only about -03 per cent. But soils that 

 have had the opportunity of accumulating N, whether in old 

 fallows or in forests, contain a higher proportion. 



CHAPTER VII. 



PHYSICAL PROPERTIES OF SOILS. 



VX7EIGHT. The specific weight of soil as it naturally 

 occurs, i.e. the weight of natural soil as compared to 

 that of distilled water varies from i to 2. Some peat soils 

 have less specific weight than i. The floating vegetable 

 gardens of Kashmir consist of light peat soil of this kind. 

 The absolute weight of soils varies from 50 to i2olbs. per cubic 

 foot. A cubic foot of distilled water weighing 62 f 5lbs. A 

 cubic foot of rich garden mould weighs about yolbs. of ordinary 

 arable land 80 to golbs. ; of dry sand nolbs. The weight of 

 an acre of soil to the depth of i foot varies from i to 5 million 

 Ibs. ; of dry sand, about 4,8oo,ooolbs. ; of loam consisting of 

 half clay and half sand 4,2oo,ooolbs. ; of ordinary arable soil 

 3,800,000 to 3,900,ooolbs. ; of stiff clay, 3,25o,ooolbs. ; of 

 garden mould 3,ooo,ooolbs.. An acre of peat to the depth of 

 i foot weighs from i to 2 million Ibs.. A soil when perfectly 

 dry was found to weigh 3, 137,ooolbs.. The same soil when 

 wet was found to weigh 4 million Ibs.. It should be remem- 

 bered i inch of rainfall increases the weight of an acre of 

 soil to a depth of i foot by about 100 tons (2,24,ooolbs.). In 

 agricultural language, a soil is said to be heavy which Coffers 



