SOILS FERTILIZERS. 



427 



Increafsccl yields and calculated profits per acre of reheat after coicpeas and 

 various phosphate applications. 



" Value of the increased yield of cowpea hay included. 



The results show a distinct tendency of lime " to lower the availability of 

 the roclv phosphate but not to affect the acid phosphate. . . . The steamed 

 bone meal, although included among the relatively insoluble phosphates, ap- 

 l)ears in these experiments to occupy an intermediate place, with returns little 

 inferior to those from acid phosphate, . . . but . . . the nitrogen contained in 

 the meal . . . probably gives it a higher standing than can be attributed to 

 the phosphoric acid alone." The results with Thomas slag, although limited, 

 " are very much in its favor, especially if a large enough application be made 

 to take the place of liming, in which event it promises to be the most profitable 

 of all the phosphates." 



A comparison of the relative profits shows that "without liming acid phos- 

 phate ranks first, bone meal second, and phosphate rock third in profitableness 

 of returns, whether the cowpeas be turned under for green manure or removed 

 for hay, but any one of the three may be used with profit. Under liming, which 

 is necessary in order to get remunerative crops of clover on these soils, and is 

 therefore fundamental to their most successful management, acid phosphate is 

 easily first, bone meal may be used with profit, but phosphate rock is liable 

 to be used at a loss." The opinion that rock phosphate " increases appreciably 

 in effectiveness with the lapse of time after incorix)ration with the soil " 

 finds little supiwrt in the results of these experiments. "A consideration of 

 the percentage of decrease in yield from the first to the last crop of wheat, for 

 each phosphated and unphosphated plat where the cowpeas were turned under, 

 shows that the unphosphated plats, as an average of the first three series, 

 declined most and that phosphate rock, bone meal, and acid phosphate followed 

 in the order named. . . . There seems ... to be little promise in phosphate 

 rock on soils like those under consideration, unless liming be omitted, and even 

 then . . . acid phosphate may be much more profitable than the untreated 

 rock." 



Sand cultures with different phosphates, I. S. Shulov {Isv. MosJcov. Selsk. 

 Khoz. Inst. (Ann. Inst. Agron. Moscou), 11 {1911), No. 2, pp. 177-198, figs. 10).— 

 The results of these experiments agreed with those of previous tests In showing 

 very good effects from many low percentage phosphatie slags. Leached ashes 

 gave good results as a source of phosphoric acid when used with rye straw ash. 

 Birch wood ashes were less effective, but still better than bone meal. When 



