June, 1912.] 



581 



Scientific Agriculture. 



water is no longer able to fill them. The 

 water then retire? and the soil particles 

 are merely united by small drops of 

 water ; further, the particles are en- 

 closed by a film of liquid continuous 

 with the drops. But the air circulates 

 between the particles and the drops. 



In this condition, certain soils lose 

 their plasticity while still retaining a 

 certain cohesion. 



3) Pellicular Condition.— When soil is 

 continuously worked, it dries rapidly on 

 account of the circulation of the air 

 through the mass. The dimension of the 

 droplets of water which unite the soil 

 particles decreases to the point where 

 capillary attraction ceases, and the 

 water exists then in the state known to 

 physicists as " superficial condition " and 

 which we call pellicular, that is to say, 

 it forms an invisible covering to the 

 particles, but the soil has still a humid 

 appearance. In this condition the parti- 

 cles adhere to one another as long as the 

 film retains a certain thickness, but the 

 soil has entirely lost its plastic property. 



4) Apparently Dry Condition. — If 

 soil is dried still further, there is no 

 longer sufficient water to cover the 

 particles and produce adherence, for it 

 retires into their microscopic cracks and 

 minute cavities ; the water content of 

 the soil, iu such a case, depends upon the 

 mineralogical nature of the particles. 



From further remarks of the author, 

 it is clear that the soils which plant 

 roots reach are generally saturated with 

 water in the pellicular state, except in 

 the following cases where the imbibition 

 is capillary. 



a) In the case of the first few centi- 

 metres below the surface after fairly 

 heavy rain, but this capillary inhibition 

 does not however continue. 



b) In less absorptive strata, such as 

 exist at a slight depth. 



c) At the level of the water-contain- 

 ing strata, or where these are situated 

 little below the surface. 



From this it may be deduced, that it is 

 not enough to study., as is usually done, 



the maximum absorption capacity of the 

 soil (capillary condition) but also the 

 method of the water circulation in the 

 pellicular condition. A plant lives upon 

 water and the nutritive substances dis- 

 solved in the latter, and thus diminishes 

 the thickness of the pellicular layer in 

 its immediate neighbourhood as a result 

 the water layer spreads out evenly 

 between the particles and makes its way 

 particularly towards the roots. Gener- 

 ally speaking, it may be said that the 

 amount of water and of the nutritive 

 substances used by the plant does not 

 depend only upon the water content of 

 the soil, but also upon the velocity of 

 of the circulation in proportion to the 

 quantity. The maximum rate of circu- 

 lation does not, however, always depend 

 upon the maximum of imbibition ; this is 

 especially the case in clay soils. 



Every soil can be described by means 

 of diagrams giving tfce proportion of 

 water and the speed of its rise (capillary 

 and pellicular). A combination of the 

 two diagrams would give the optimum 

 degree of imbibition for the develop- 

 ment of a plant. 



By this method, a rational method of 

 irrigation and drainage could be estab- 

 lished. 



EXPERIMENTS ON PADDY CULTIV- 

 ATION DURING THE YEARS 1909-11, 



(From the Department of Agriculture 

 Mysore State Bulletin, No. 2, 1912.) 



Previous to his retirement in 1908, 

 Dr. Lehmann, formerly Agricultural 

 Chemist to the Government of Mysore, 

 planned certain important experiments 

 on the cultivation of paddy. The nature 

 of these experiments is briefly described 

 by him in his last, or 9th, Annual Raport 

 for the year 1907-08, pages 19-21, where 

 he also indicates the various numbered 

 plots that are to be used for the different 

 experiments. 



These experiments have been carried 

 on ever since his retirement and the 

 number and character of the results 

 obtained now warrant their being pub- 

 lished as a bulletin of the Department, 



