310 ACTIONS OF ARTIFICIAL MANURES 



SUMMARY. 



1. The long-continued use of sulphate of ammonia on soils 

 poor in lime, results in the soils becoming acid. 



2. The acidity is caused by certain micro-fungi in the soil, 

 which split up the sulphate of ammonia in order to obtain the 

 ammonia, and thereby set free sulphuric acid. 



3. The infertility of such soils is due to the way all the 

 regular bacterial changes in the soil are suspended by the 

 acidity; instead fungi permeate the soil and seize upon the 

 manure. 



4. The remedy, as may be seen upon the Woburn plots, is 

 the use of sufficient lime to keep the soil neutral. 



5. From the Rothamsted soils carbonate of lime is being 

 washed out at the rate of 800 to 1000 Ib. per acre per annum, 

 the losses being increased by the use of sulphate of ammonia, 

 but lessened by dung or nitrate of soda. 



6. Nitrate of soda, when applied to heavy soils in large 

 quantities, destroys their texture. 



7. Some of the nitrate of soda gets converted into carbonate 

 of soda by the action of plants and bacteria, and carbonate of 

 soda, by deflocculating the clay particles, destroys the tilth. 



8. The best remedies are the use of soot or superphosphate ; 

 the best preventive is the use of a mixture of nitrate of soda 

 and sulphate of ammonia instead of either separately. 



9. Soluble potash manures and common salt may also injure 

 the tilth of heavy soils through the production of a little 

 soluble alkali by interaction with carbonate of lime in the soil. 

 The remedy is to apply such manures in the winter or in 

 conjunction with superphosphate. 



REFERENCE 



"Some Secondary Actions of Manures upon the Soil," by A. D. H., J.R.A.S., 

 71 (1909). 



