834 EXPEKIMENT STATION RECOBD. [Vol.85 



this study. A study of 150 sq. ft. of soil sampled by taking a core from the 

 center of each square foot to a depth of 12 in. brought out the fact that it was 

 rarely the case that contiguous square feet of soil showed so small a difference 

 in total nitrogen as 0.001 per cent. The actual difference reached 0.0354 per 

 cent, or more than 35 times as much as would have a considerable significance 

 in the development of the crop, if present in the form of nitric nitrogen. 



A study of the effect on the composition of the plant of different amounts of 

 water applied to the soil, the composition of two series of samples which 

 received 30.77 in. of water in all, 24 in. irrigation and 6.77 in. rainfall, being 

 compared with the composition of 16 series grown with 18.77 in. of water, 12 in. 

 irrigation and 6.77 in. of rainfall, brought out no differences in the amount of 

 nitrogenous compounds in the plants that could be attributed to the varying 

 amounts of water applied. In 1915, when the crop again received about 19 in. 

 of water, differences in the composition of the plants up to the end of July 

 were considered due to the fact that plants were thoroughly moistened by 

 application of water almost daily as the result of the prevailing weather con- 

 ditions. Later the abundant development of rust as a result largely of the 

 moisture on the plants began to play a still more important part in this direc- 

 tion. The general effect was to suppress all forms of nitrogen present in the 

 plant as well as the ash constituents throughout its growing period. The 

 size of the plants and the percentage of dry matter were not materially differ- 

 ent in the two seasons. 



The very different weather conditions prevailing during the two seasons are 

 believed to have demonstrated that the observed effects of the fertilizers 

 applied in 1913 are independent of the weather. It is further stated that 

 while the weather conditions of 1915 made great differences in both the nitro- 

 gen compounds and ash constituents of the plants, they did not obscure the 

 effect of the nitrogen applied on the total, or the proteid nitrogen, or the silicon, 

 or the ash constituents in general. The same is regarded true with respect to 

 the effects of phosphorus and potassium. It is stated that the effect of the 

 application of nitrogen was to increase the nitrogen in all parts of the plant, 

 to reduce the percentage of dry matter and the percentage of silicon, to increase 

 the percentage of potassium, calcium, and magnesium, as a rule, to increase 

 also the total ash, and to remain neutral relative to the amount of phosphorus 

 in the plant. The application of nitrogen is reported also as increasing the 

 height of the plant, the length of the head, and the color of the plant, but as 

 not increasing the kernels per spikelet. Phosphorus seemed to be indifferent 

 to or possibly tended to depress the amount of the nitrogen in the different 

 parts of the plant, and the same was true of potassium, except that this 

 element showed a stronger tendency to depress the nitrogen. Both phos- 

 phorus and potassium depressed the phosphorus in the plant. These ef- 

 fects upon the composition of the plant were apparently not changed by the 

 weather conditions. The effect of the application of nitrogen in the form of 

 sodium nitrate in the production of flinty and often shrunken kernels was not 

 changed in the wet season of 1915, The weather conditions of 1915 as com- 

 pared with those of 1913 are further considered as having been without 

 material effect on the occurrence of yellow-berry. The attack of rust seemed 

 to affect materially the course of the chemical changes that took place after 

 the early part of August, 1915, as compared with those taking place during 

 the ripening period of the plant in 1913. 



Distinguishing characters of the seeds of Sudan grass and Johnson grass, 

 F. H. HiLLMAN iU. S. Dept. Agr. Bui. 406 {1916), pp. 5, figs. 5).— This bulletin 

 enumerates and describes the distinguishing characters of seeds of Sudan grass 

 and Johnson grass, and points out the apparent exceptions to these characters. 



