414 



SOILS. 



putra water to compare with that of the Ganges. That tea 

 should flourish for twenty to thirty years in such soils, is a 

 good indication of one cause at least of the total failure of tea 

 culture in California, where tea plants are difficult to maintain 

 alive, and after 25 years form rounded, scrubby bushes not 

 over four feet high. Similar failures of tea on calcareous soils 

 are on record from India. The low lime-content of the Assam 

 soils, then, does not necessarily imply that these soils should 

 be limed to maintain tea production. According to Mann, 

 the main deficiency is in nitrogen, as the figures imply; but 

 whether his recommendation of green-manuring with legu- 

 minous crops to increase the nitrogen-supply is practicable 

 without first supplying more lime to the Assam soils, is ques- 

 tionable. Since phosphoric acid is also low, his recommenda- 

 tion to use freely the basic or Thomas slag is doubtless a good 

 one, since lime would thus also be moderately increased. 



Bamber gives a number of analyses of tea soils from low 

 ground in Assam, which are very rich in vegetable matter and 

 quite acid. Like those reported by Leather, these " bhil " soils 

 are very poor in lime and nitrogen, but fairly supplied with 

 potash and phosphoric acid. 



The Regur or Black Cotton Soils of Southern India. The 

 second-greatest reasonably uniform soil-area of India is that 

 covered by the regur, or black cotton soils, in south central 

 India, notably the Deccan. where these soils are said to have 

 been cultivated without fertilization for 2000 years and are still 

 fairly productive. 1 Both in their physical character, chemical 

 composition, and cultural characteristics, these regur soils 

 are very similar to the " prairie soils " of the Cotton states 

 and especially to the " black adobe " of California. Like the 

 latter they are of unusual depth without change of tint ; they 

 crack wide open during the dry season on account of their high 

 clay content; and the soil is thus partly inverted by the surface 

 soil falling into the cracks. To the latter fact Leather as- 



1 That is to say, they now produce about 600 pounds, or 10 bushels of wheat 

 per acre, as do the Rothamstead soils after fifty years' exhaustive cultivation. 

 Probably both have come down to the permanent level of production correspond 

 ing to the amount of plant-food made currently available each year by the fallow- 

 ing process in originally very rich soils. The present product of cotton on the 

 regur lands does not seem to be on record; judging by the wheat product it 

 should not be over one hundred pounds of lint per acre. 



