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contain valuable reserve materials of food which gradually 

 get dissolved and made available as plant food. But an 

 admixture of large sized stones in the soil is certainly not 

 desirable, as they interfere with proper aerification of soil, 

 germination of seed and penetration of roots. The agricul- 

 turist should not only have an idea of the composition of his 

 soil and of the stones which are found in the soil, but also of 

 the subsoil or the soil immediately below the surface soil in- 

 terpenetrated with the roots of deep-rooted plants. The 

 subsoil is more compact in appearance and is usually of a 

 lighter colour. It is very important that the subsoil should 

 be richer than the soil, and if the soil is sedentary, that the 

 underlying rock should be composed of substances which are 

 valuable for plant life. In transported soils also, valuable 

 minerals, such as ghuting lime or kankar and gypsum may be 

 found buried within easy reach of the surface. Chemical 

 analysis does not always give a correct idea of the actual 

 present value of a soil, subsoil, or rock, but it tells us of their 

 possible ultimate value. In a hard rock scarcely any plant 

 food exists in an available form, and nothing will grow on 

 such rock. In the case of soils also a great deal depends on 

 cultivation and not on their potential richness as found out by 

 chemical analysis. Analysis, for instance, shows, that the 

 soil of the Sibpur Experimental Farm is richer than those of 

 the Burdwan and the Dumraon Experimental Farms. But 

 we actually get at Sibpur poorer crops. The soil of the Sibpur 

 Farm is a hard clay which is difficult and more expensive to 

 cultivate and under the same treatment this soil does not 

 yield such heavy crops as soils actually poorer but which are 

 easier to cultivate. Nevertheless a knowledge of the com- 

 position of soils and rocks is of great practical value to the 

 scientific farmer. He knows what plant food there is, and 

 it rests with him how much of it he can or he ought to make 

 available for a certain crop. A soil may be too fertile and 

 the fertility of a soil may be too quickly exhausted. Deep 



