HAPPY INDIA 77 



This does not take anything out of the soil. The 

 plants will not grow except with the aid of some 

 mineral substances. Lime, potash, phosphorus are 

 among the chief mineral substances, and these are 

 taken out of the soil by the plant of which they 

 constitute only a minute fraction ; and if the plant 

 is afterwards removed, the soil is deprived of those 

 substances ; and if the removal of these minerals is 

 continued year after year it is probable that the 

 soil will run short. It very often happens that the 

 amount of lime originally in the soil is so great that 

 it is never necessary to bring lime from other places 

 to recoup the amount taken away with the plants 

 that are removed. But with regard to potash and 

 phosphorus, it generally happens that if repeated 

 crops are taken from the land year after year, these 

 necessary elements will run short, and then the 

 crops will be poor. Nitrogen is also necessary for 

 the growth of the plant. This, too, comes out of 

 the air, and it is necessary to restore it to the land 

 by some other method. The growing of leguminous 

 plants will restore nitrogen to the land. A suitable 

 crop is often sown, and when well grown is ploughed 

 into the land when green ; this is effective, but causes 

 the loss of that season. The nitrogen is generally 

 given to the land in Europe in the form of nitrate 

 of soda, or sulphate of ammonia. Phosphorus is 

 given to the land in the form of superphosphates, 

 which may be made from bones or from a mineral, 

 tricalcic phosphate of lime. Phosphate of lime 

 ground small is often given to the land instead of 



