518 EXPERIMENT STATION RECORD. [Vol.43 



iiscd. Moi'c water-soluble potiissiuiu was formed in the composts containiiis the 

 liiKli-potassium greensaiul, but a lurj^er percentage of the total potassium 

 I)resent was liberated in the composts containing the low-potassium greensand. 

 In tlie composts containing manure, the total amounts of potassium recovered 

 in the water extracts varied from 9.1 per cent to a maximum of 41.3 per cent 

 of the total initial amount present. 



Farmyard manure: Its miakiiig and use, E. J. Russell {Jour. Farmers' 

 Club [London], li)20, pt. 5, pp. 89-106). — Tiiis is a popular dissertation on the 

 sul).1ect. 



Plant analyses and the fertilizer requirements of soil, MCntkr {Jour. 

 Lmulir., 67 (1019), No: 4, pp. 229-;iG6).— The results of fertilizer and rotation 

 exi)eriments begun in 1902 with beets, barley, potatoes, and wheat on a loess 

 loam soil are reported. 



Final results were obtained with wheat only. It wa.? found that potash and 

 pho.sphoric acid fertilization increasetl the silica content of wheat straw, and 

 nitrogen fertilization reduced it. Potash and phosphoric acid fertilization 

 reduced the nitrogen, lime, and magnesia contents of the straw, and nitrogen 

 fertilization increased them. Potash slightly reduced the nitrogen content of 

 the grain, and phosphoric acid strongly depressed it. A chemical analysis of 

 the wheat plant from fertilized soil gave no sure indication of the fertility 

 condition of the soil. 



It was further found that in good cropping years nitrogen' had the greatest 

 influence on crop growth, and in poor years potash had the greatest Influence. 

 Phosphoric acid acted indifferently in this respect. Fertilization with an excess 

 of nitrogen, potash, or phosphoric acid was mainly evident in the straw. The 

 weather conditions of a year exercised a strong influence on the assiOiilation 

 of nutrients by wheat, and the relative percentage of nutrient content was 

 more strongly influenced in individual years by the weather than by fer- 

 tilization. 



It is believed that the nitrogen recpiirements of the soil used are indicated 

 by the contents of nitrogen, lime, and magnesium in the wheat plant. When 

 the sum of these three for 1 hectare exceeds 90 kg. in tlie grain and straw, 00 

 kg. in the grain alone, or 30 kg. in the straw alone, thei'e is sullicient nitrogen 

 present in tlie soil. If, after subtracting the sum of these three, the figures 

 for the potash percentage are positive, there is sufficient soil potash, but if 

 negative the soil is deficient in potash. 



The wheat plants on plats receiving no fertilization and complete fertilization 

 showed generally the same percentage content of nitrogen and phosphoric acid, 

 while the potash content of the straw was higher on the completely fertilized 

 plats. A comparison of analyses of plants from unfertilized and completely 

 fertilized plats gave no indication of the fertilizer requirements of the soil. 



It is concluded that the fertilizer requirements of a soil are best indicated 

 when studied by growing and analyzing plants under two excess fertilizations, 

 namely, nitrogen and phosphoric acid plus potash. If the nitrogen : potash ratio 

 is narrower than 1 : 2 there is a potash deficiency. If the nitrogen : phosphoric 

 acid ratio on the nitrogen plats is wider than 100: 35 thei'e is a phosphoric acid 

 deficiency. If the ratio of nitrogen to phosphoric acid on the phosphoric acid 

 potash plats is narrower than 100 : 60, or if the silica : nitrogen ratio is greater 

 than 100 : 6 there is a nitrogen deficiency. If the percentage of nitrogen found in 

 the wheat straw from the nitrogen plat is placed at 100 there is sufficient nitro- 

 gen present in the soil of the phosphoric acid potash plat provided the ratio of 

 the two nitrogen percentages Is narrower than 100 : 60. 



The content of phosphoric acid in the oats iilant and its relation to the 

 increased yield produced by fertilization, E. A. Mitscheelich {Jour. Landw., 



I 



