FERTILIZERS. 235 



of soda, sulphate of ammonia, guano, ground bone, dried l)lood, cattle manurend, a 

 a number of other organic forms of nitrogen. 



It was found in the pot experiments that 100 parts of ammoniacal nitrogen yielded 

 93 parts of nitric nitrogen in the soil. The average results of the pot experiments 

 showed that the different nitrogenous fertilizers M'ere utilized by crops in the follow- 

 ing relative proportions: Nitrate of soda TOO, ammonium salts 94, Damarara guano 

 91, Peruvian guano 87, green manures 77, horn meal 74, dried blood 73, castor pomace 

 73, poudrette (Bremen) 60, Krottnauer manure 51, Blankenburger manure 49, wool 

 dust 26, concentrated cattle manure 22, ground leather 16, sea ooze 12, sediment from 

 settling reservoirs 10. In experiments with oats, ammonium salts were 98 per cent 

 as effective as nitrate of soda in producing grain and 97 per cent as effective in pro- 

 ducing straw. It appears also from the results of experiments with oats, beets, and 

 carrots that soda had a decided effect in increasing the yield. 



In the field experiments with barley, oats, wheat, rye, potatoes, and beets the rela- 

 tive effectiveness of nitrate of soda and ammonium sulphate was as 100 : 70. The 

 lower effectiveness of the latter is attributed to loss of nitrogen in form of ammonia. 

 In the field experiments, as in the pot experiments, it was found that soda produced a 

 decided effect in increasing yields and that nitrate of soda and sulphate of ammonia 

 produced the same relative proportions of straw and grain or leaves and roots. The 

 possible injurious effect on the physical properties of soils of the continued use of 

 sodium salts, like nitrate of soda, is cautioned against. 



The method of making the field experiments is fully described. 



Tlie effects on plants of a deficiency of nitrogen, phosphoric acid, or potash, 

 H. WiLFARTH and G. Wimmer {Jour. Landw., 61 {1903), No. 2, pp. 129-138, pis. 3). — 

 A summary is given of the results of pot and field experiments extending over sev- 

 eral years with potatoes, sugar beets, tobacco, buckwheat, and a number of other 

 plants, including fruit trees. The pot experiments were made by the method fol- 

 lowed at the Bernburg experiment station, « using pure sand mixed with 6 per cent of 

 purified peat. 



It was observed that a marked deficiency of any of the essential fertilizing con- 

 stituents resulted not only in a decrease in yield, but often in some change in the 

 percentage composition of the plant substance. The latter effect was most marked 

 in the carbohydrates in case of a deficiency of phosphoric acid. With a marked 

 deficiency of nitrogen, the percentage of carbohydrates was oftener higher than lower. 

 With a deficiency of phosphoric acid there was a small decrease. Thus sugar beets 

 insufficiently supplied with nitrogen contained a larger percentage of sugar than those 

 abundantly supplied, while a deficiency of phosphoric acid resulted in a reduced 

 percentage of sugar. 



The effect of a deficiency of one or the other of the essential fertilizing constituents 

 was also shown in the relative proportion of roots and leaves, as in sugar beets, but 

 especially in the appearance of the leaves. Observations on the latter i)oint are 

 recorded in detail and it is claimed that in case of sand and water cultures the leaf 

 appearance furnishes a reliable means of determining whether the plant needs nitro- 

 gen, phosphoric acid, or potash. The indications are not so reliable in case of field 

 experiments. 



The leaves of plants suffering from nitrogen hunger were light-green to yellowish, 

 finally drying to a light brownish-yellow color. With a deficiency of phosphoric acid 

 the leaves were deep green, but showed black spots beginning on the edges but 

 spreading over the whole leaf, which finally dries up to a dark brown or dark green 

 color. In cases of very severe phosphoric^ acid hunger the leaves of sugar beets curl 

 under from the tips, but as a rule the leaves of plants suffering from nitrogen and 

 phosi)horic acid hunger are of normal shape and general appearance, although 

 reduced in size. 



«Arb. Deut. Landw. Gesell., Nos. 34 and 68. 



