No. 4.] CLOVERS. 431 



be more available than the phosphoric acid in any of the phosphatic 

 rocks, or even in most of the forms of bone. Besides phosphoric acid, 

 the slag meal contains a large amount of lime, and this, while less 

 effective in correcting the faults of a sour soil than quicklime, must 

 prove valuable in helping to prevent soils which have once been brought 

 into proper condition from becoming sour again. On such soils as 

 those at Amherst the application of slag meal at the rate of some 500 

 or 600 pounds per acre in connection with such dressings of manure 

 as have been indicated appears to be sufficient. In addition to the slag 

 meal, there will be needed on most soils to bring them into suitable 

 condition for producing clovers a fairly liberal application of potash 

 in some form, for this element the 4 or 5 cords of manure will not sup- 

 ply in sufficiently large quantities for the best results with clover. 

 Wood ashes furnish potash in very desirable form, but they are becom- 

 ing increasingly scarce, and are held at prices which make them a 

 relatively expensive source of that element. It is the practice on the 

 college farm to depend mainly upon some of the German potash salts ; 

 and, as has been pointed out in earlier articles on the hay crop, sul- 

 fates of potash are found in the long run to give much better results 

 with clover than muriate of potash or kainite. Experiments now in 

 progress in Amherst are furnishing an interesting basis of comparison 

 between the low-grade sulfate of potash and the high grade. The 

 writer is not yet prepared to recommend the low grade as superior to 

 the high grade; and, since the latter furnishes actual potash at the 

 lower cost, it is his belief that it should usually be selected. Com- 

 parative observations, however, on crops grown on the two potash 

 salts this year lead him to wonder whether the magnesia of the low- 

 grade sulfate may not ultimately prove valuable. Certainly better 

 clover is seldom seen than that produced on certain of the fields of the 

 college farm during the past year, which have been during the past 

 few seasons top-dressed with basic slag meal and low-grade sulfate of 

 potash. If the high-grade sulfate of potash, however, is selected for 

 use in connection with manure in preparing for clover, it is believed 

 that an annual application at the rate of about 150 to 175 pounds per 

 acre will supply the element potash in sufficient quantities for clovers 

 on most soils. These materials (basic slag meal and sulfate of potash) 

 should be mixed after the land has been plowed, spread broadcast 

 and harrowed in. 



Fertilizers without Manures. 

 In some cases the farmer will desire to bring his soil into suitable 

 condition for clovers in rotation by application of fertilizers alone to 

 preceding crops. In such cases the materials which have just been 

 considered should constitute the main reliance, but they should be 

 used in connection with materials which will furnish nitrogen in suffi- 

 cient quantities for the preceding crops. Both the slag and potash. 



