364 



SCIENCE 



[N. S. Vol. XLV. No. 1163 



some light on the comparison of a uniform 

 limestone, which had been subjected to varying 

 degrees of pulverization, with calcium oxide. 

 During the progress of the work, Thomas and 

 Frear^ published results which are similar to 

 those obtained in the present instance. 



Several soils which may be regarded as 

 typical of rather extensive fertile areas were 

 obtained through the courtesy of Drs. P. E. 

 Brown, 0. E. Thome, C. A. Mooers, W. J. 

 Schoene and W. P. Kelly; respectively desig- 

 nated as Carrington (Iowa) silt loam, Wooster 

 (Ohio) silt loam, Cumberland (Tennessee) 

 silt loam, Norfolk (Virginia) sandy loam, 

 Sierra (California) sandy loam and Ports- 

 mouth (ISTew Jersey) acid muck. Ten-pound 

 earthenware pots were filled with soil and lime- 

 stone of 20-40, 60-80, 100-200, 200 4- mesh 

 and calcium oxide (c. p.) were added in suffi- 

 cient quantities to satisfy the lime require- 

 ments of the various soils as determined by 

 the Veitch method. Fifteen crimson clover 

 plants were grown in each pot maintained 

 under optimum moisture conditions in the 

 greenhouse. A summary of the results obtained 

 on the five more important soils is recorded 

 in Table I. It is evident that in general, in 



TABLE I 



Summary sJiowing Melative Effect of Fineness of 



Division of Pulverized Limestone and CaO on 



the Yield of Crimson Clover on Various 



all the soils studied, there is an increase in 

 crop yield (dry weight) as the fineness of the 

 limestone is increased. Averaging the five 

 soils it will be seen that the yields with 200-M. 

 are fully one third again as large as where 



2 Thomas, W., and Frear, W., Jour. Ind. Eng. 

 Chem., Vol. 7, No. 12 (1915), p. 1,041. 



20-M. limestone was employed, and practically 

 double the yield on the imlimed pots. There 

 is little choice, however, between the 200-M. 

 limestone and calciiun oxide, the former giv- 

 ing maximum results on the Ohio and Tennes- 

 see soils, while the latter proved superior on 

 the Norfolk and Iowa soils. 



An analysis of these crops for total nitrogen 

 (Kjeldahl method) indicated the same general 

 relationship, as is shown in Table II. Namely, 



TABLE n 



Summary sliowing Helative Effect of Fineness of 



Division of Pulverized Limestone and CaO on 



Total Nitrogen {in Gm.) of Crimson 



Clover on Various Soils 



as the fineness of division of limestone in- 

 creased, the total nitrogen (in gm.) increased. 

 Two-hundred-mesh limestone was again supe- 

 rior to calcium oxide in two of the four 

 instances. 



The California soil, being decidedly alka- 

 line, responded imfavorably to the applica- 

 tion of limestone. That is, the yield of clover 

 as well as the total nitrogen decreased with 

 increasing fineness of division of pulverized 

 limestone. "With the acid muck soil (Ports- 

 mouth), however, the results were similar to 

 those obtained with the other typical soils, i. e., 

 an increase in fineness of division was respon- 

 sible for an increase in crop yield and total 

 nitrogen. 



After the clover had been harvested, the lime 

 requirements of the soils were again deter- 

 mined for the purpose of comparing the rela- 

 tive neutralizing efficiency of the different 

 materials. As might be expected from theo- 

 retical considerations the lime requirement 

 tended to decrease as a result of the applica- 



