32 



different brands vary widely, they show an improvement over con- 

 ditions which prevailed a year ago. Gypsum has been listed with 

 the other lime compounds, but it should be understood that this 

 product is not to be used to sweeten soul" soils. 



Vegetation Experiment to Determine the Nitrogen Activity of Several 

 Commercial Fertilizers Taken From 1914 Inspection, and a 

 Comparison with the Laboratory Method (Alkaline Perman- 

 ganate). 



The vegetation experiment work instituted a year ago to furnish 

 a comparison between the chemical or laboratory method, and the 

 actual nitrogen activity by pot experiment in some of the fertilizer 

 brands sold in Massachusetts, furnished sufficient valuable data to 

 warrant its continuation this season on a somewhat more elaborate 

 plan. 



A greater variety of fertilizers was selected than in the previous 

 experiment and the comparison includes recovery or yield of nitrogen, 

 as well as dry matter. 



The soil was taken from Plot 1 1 , south soil test, ex- 

 Outline of periment station plots. Analysis showed it to con- 



the tain .125 per cent of total nitrogen. Each pot held 



Experiment. 43 pounds of soil and was filled with a mixture com- 

 posed of 1 part of soil and 2 parts of sifted sand, 

 which carried .0039 per cent of total nitrogen. One hundred grams 

 of decomposed straw were applied to each pot to furnish organic mat- 

 ter necessary to produce normal conditions. This would be equiva- 

 lent to about 4 cords per acre. The fertilizer and lime used were 

 thoroughly mixed with the soil in each pot. The source of each in- 

 gredient was as follows: 



Lime: Each pot received 27.52 grams of fine ground marl, this 

 amount being necessary, according to the Veitch method, to produce 

 a neutral soil. This application would be equivalent to 2 tons per 

 acre. 



Potash: Each pot received 10 grams of high grade sulfate of 

 potash, analyzing 49.92 per cent water soluble potash, equivalent to 

 1320 pounds per acre. 



Phosphoric Acid: Each pot received IS grams of acid phosphate 

 testing 14.57 per cent of available phosphoric acid, and 18 grams of 

 basic slag phosphate testing 14.80 per cent phosphoric acid, equiva- 

 lent to 2800 pounds of acid phosphate and 2800 pounds of basic slag 

 phosphate per acre. 



Nitrogen: A good quality of dried, red blood, ordinarily used 

 for feeding domestic animals, was selected as a standard. One 

 series (8 pots) received an application of .42 gram of nitrogen per 

 pot, (59.5 pounds of nitrogen, 502 pounds of dried blood per acre) ; 



