320 EXPERIMENT STATION RECORD. 



i^bowing the most marked effect in this respect and tbe nitrate being least in- 

 jurious. A slight tendency in tbe same direction was observed with potassium 

 carbonate, but with none of the other salts of potash. With even as little 

 as 0.0037.5 parts of lithium in 100 parts of soil a harmful effect on the wheat 

 crop was observed. 



In connection with experiments with green manures, tests were made of the 

 effect of adding colloid substances like aluminum silicate, sodium silicate, kao- 

 lin, lime, and magnesia. It was found that the addition of aluminum silicate 

 resulted in a large increase in crop on soils green manured with tares and 

 mustard. A less increase was observed with sodium silicate, and no effect 

 with kaolin. The increase is attributed to the improved physical condition of 

 the soil resulting in larger retention of moisture. 



The experiments with magnesia showed that the use of this substance in the 

 form of sulphate is not beneficial, but that it may be used with benefit in 

 insoluble forms so long as the percentage of magnesia in the soil does not 

 exceed that of lime. 



The experiments on fen soils indicated that such soils are benefited by general 

 manuring with mineral and nitrogenous fertilizers in spite of the fact that the 

 soils are already rich in nitrogen. 



In experiments with barley grown continuously iron sulphate, copper sul- 

 phate, and pyrogallic acid proved of no value in correcting the acidity produced 

 in the soil by continuous use of ammonium sulphate. The yield was increased 

 by the use of 0.1 per cent of animal charcoal, but the nature of the action of 

 this substance was not made clear. 



Slight increases in the yield of white, mammoth, and red clover, and alfalfa 

 resulted from inoculation with nitro-bacterine. 



Some secondary actions of manures upon the soil, A. D. Hall (Jour. Roy. 

 Agr. Soc. England, 10 (1909), pp. 12-3.5). — On the basis mainly of expeiiments 

 carried on at Woburn and at Rothamsted the author draws the following con- 

 clusions : 



"The long-continued use of sulphate of ammonia on soils poor in lime results 

 in the soils becoming acid. 



"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. 



" 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. 



"The remedy, as may be seen upon the Woburn plats, is tbe use of sufficient 

 lime to keep the soil neutral. 



" From the Rothamsted soils carbonate of lime is being washed out at the 

 rate of 800 to 1,000 lbs. per acre per annum, the losses being increased by the 

 use of sulphate of ammonia, but lessened by dung or nitrate of soda. 



" Nitrate of soda, when applied to heavy soils in large quantities, destroys 

 their texture. 



" 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. 



" The best remedies are the use of soot or superphosphate ; the best pre- 

 ventive is the use of a mixture of nitrate of soda and sulphate of ammonia 

 instead of either separately. 



" 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 car- 



