ACTION OF GYPSUM ON CLOVER. '541 



Dr. Pincus of Insterburg are the most important, both on 

 account of the careful manner in which they were con- 

 ducted, and the conclusions drawn from them. At Dr. 

 Pincus' request, thi'ce plots of ground, each of a morgen 

 (about ^ of an acre) in extent, and lying close together, 

 were selected by Mr. Eosenfeld in the beginning of May, 

 from the middle of a large clover field in the neighbour- 

 hood of Lenkeningken. The clover crop had a very pro- 

 mising appearance, and the plants were then about an inch 

 high. One of the plots was manured with a cwt. of 

 gyjDsum, the sec(3nd with the same quantity of sulphate of 

 magnesia, and the intervening plant was left unmanured. 

 The clover field from which the plots were selected was 

 one of the best cidtivated and most fertile in the district, 

 and had produced in the preceding summer an abundant 

 rye crop. The plants growing on the unmanured plot, 

 when compared with those on the manm'cd, very speedily 

 presented a difference of colour and condition. 



On the plot manured with gypsum, they were of a 

 deeper green, and stood higher. The difference was most 

 striking at the time of flowering, which occurred in the 

 unmaniured plots four or five days earher than in the 

 manured ; the whole field being everywhere in full bloom, 

 when scarcely a flower was to be seen in the manured 

 plots. When the manured plots also were in flower the 

 clover was mown (May 24:t\\). A square rutlie was mea- 

 sured from each of the experimental plots, and the clover 

 separately cut and weighed. 



Calculated per Prussian morgen (=^ of an acre), the 



results were, C^vte. of clover-hay 



per morgen 



Without manure . . . . . 2r6 cwts. 



With gypsum 30- 6 „ 



With sulphate of magnesia . . . 32"4 „ 



On a closer examination of the clover-hay it -was found 



