FERTILIZERS. 



555 



compounds in the animal manures exceeds almost double that of the phosphoric 

 acid compounds in the manures of vegetable origin in the tirst year. (7) In the 

 second yearthe relative action of the vegetable manures increased to a certain extent, 

 yet it still remained behind that of the animal manures." 



On the action of various insoluble phosphates upon rice plants, M. Nagaoka 

 {Bui. Col. Agr., Tokyo Imp. Univ., 6 (1904), No. 3, pp. 215-261).— The experiments 

 here reported were made in wooden boxes somewhat less than 1 square meter in area 

 and partially sunk in the soil. The phosphates used were double superphosphate 

 (for comparison), ferric phosphate, ferrous phosphate, aluminum phosphate, and 

 calcium phosphate. The soil used was taken from a paddy field which had been 

 exhausted by 4 years' continuous culture of rice without manure. Each phosphate 

 was used at three different rates, 25, 50, and 100 kg. per hectare (22.26, 44.53, and 

 89.07 lbs. per acre). 



The experiments extended over 4 years and were divided into different series for 

 the purpose of testing the relative direct effect of the phosphates and their after effects 

 with and without the addition of lime. All of the phosphates showed considerable 

 direct benefit both on the straw and on the grain of the rice, and this benefit increased 

 with the increase in the amount of phosphate applied. In the study of the after effects 

 of the phosphates it was found in all cases "that the unrecovered phosphoric acid had 

 an influence to a certain extent on the second crop. However, there was no case in 

 which the crops of the second year exceeded that of the first year. Further, the 

 greater the amount of phosphoric acid left from the preceding year, the larger was 

 the harvest." 



The relative effect of the different phosphates in each of the 4 years of the experi- 

 ment is shown in the following table: 



Relative effect on rice of different phosphates during four years. 



First Second Third Fourth 

 year. year. year. year. 



Double superphosphate 



Ferric phosphate 



Ferrous phosphate 



Aluminum phosphate . 

 Calcium phosphate 



100 

 140 

 87 

 92 

 117 



inn 

 111 



145 

 110 



100 

 399 

 194 

 514 

 161 



100 

 58 

 44 

 112 

 118 



In the experiments in which lime was used it was shown that applications of caustic 

 lime and calcium carbonate reduced the amount of phosphoric acid assimilated by 

 plants, the former being much more active in this respect than the latter. This action 

 of caustic lime is attributed in part to its neutralizing effect on acid humus and the 

 acid secretions of plants. The assimilation of phosphoric acid by the plants during 

 the second and subsequent years was greater on the limed soil than on the unlimed 

 soils, but this increase was not sufficient to compensate for the decreased yield during 

 the first year due to liming during the first year. Examinations of samples of the 

 soil showed that the application of caustic lime had decreased the solubility of the 

 phosphoric acid in neutral ammonium citrate and acetic acid. A similar but less 

 pronounced result was brought about by the calcium carbonate. 



In a supplementary note on these investigations O. Loew points out that the unsatis- 

 factory action of the lime may be due in part at least to the fact that the ratio between 

 the lime and magnesia in the soil experimented with was already that shown by Aso 

 (E. S. R., 15, p. 1062) to be most favorable to the growth of rice, viz, 1:1. 



On the effects of soil ignition upon the availability of phosphoric acid for 

 rice culture in paddy fields, M. Nagaoka (Bui. Col. Agr., Tokyo Imp. Univ., 6 

 (1904), No. 3, pp. 268-276, pis. 3).— Experiments to determine the effect of igniting 

 paddy soil for 15 minutes to faint redness, to remove the humus, on the availability 

 of phosphoric acid are reported. The results show that the availabi'Hy of the phos- 

 17604— No. 6—05 i 



