312 



EXPERIMENT STATION RECORD. 



Although the above examples show a marked influence of the fer- 

 tilizing materials, in or applied to the soil, on the content of these 

 materials in the ash, it should be mentioned that this effect is not 

 always as marked and may disappear entirel}^ or in some cases be 

 quite the reverse of that noted. This may be due to the fact that 

 when an element, as potash, is present in the soil or fertilizer in insuf- 

 ticient amount, the plants develop poorly and give only a ver}" poor 

 yield; while when fertilized with potash a much larger yield is 

 obtained. When the plants grown without potash fertilizer are incin- 

 erated, an absolutely smaller amount but a relatively much larger 

 amount of potash may be found in the ash, while the larger jneld 

 obtained with potash manuring may show an absolutely larger amount 

 of potash without the percentage of potash being increased. It must 

 b& borne in mind that there are alwa3\s several factors which influence 

 the absolute amounts of plant food taken up by the plant, as well as 

 the percentage composition of the ash. For example, the presence of 

 nitrogen in the fertilizer or the soil has a great influence, since it pro- 

 motes a vigorous growth, and the increased yield, consisting largely 

 of organic matter, results in a suppression of certain ash elements of 

 the plant (and a preponderance of others). This is shown, for exam- 

 ple, in the above-mentioned experiments of von Seelhorst, in which 

 the average percentages of phosphoric acid and potash in the air-dry 

 matter of the oat plant were as follows: 



Potash and jihosphoric acid in oat plants differently fertilized [von SeeUiorst). 



Fertilizer applied. 



Potash Phosphoric 

 foiasn. j^pj^_ 



Potash 



Potash and nitrogen 



Nitrogen 



Without fertilizer 



Phosphoric acid 



Phosphoric acid and nitrogen . 



Per cent. 

 2.997 

 2.292 

 1.536 

 2.122 

 2. 17.5 

 1.348 



Per cent. 

 0.597 

 .403 

 .413 

 .588 

 .735 

 .472 



INFLUENCE OF THE THICKNESS OF THE STAND. 



It is well known that the growth and development of plants vary 

 greatly with close and thin planting. It is true of plants in general 

 that they develop better when each plant stands by itself than when 

 they are set close together, and it is evident that this is due to the 

 greater area of soil at the disposal of the plant, as well as the increased 

 amount of light and air. When plants have more soil space in which 

 to grow, they naturally have more plant food at their disposal and more 

 moisture, and this condition must influence the amount and the com- 

 position of the plant ash. As illustrating the above points, the experi- 

 ments of von Seelhorst and Panaoto vie ^ with spring wheat and oats 



^Jour. Landw,, 47 (1899), p. 379. 



