FERTILIZERS. 635 



Plats manured with nitrogenous fertilizers gave the best results, but 

 in experiment ~No. 2 all the fertilizers had very little, if any, effect. 



!No advantage was gained by applying potash, phosphoric acid, and 

 lime to a crop of peas to be used by them before turning under for cot- 

 ton and corn instead of applying these fertilizers directly to the corn 

 or cotton crop. 



Manure experiments with wheat on sandy soils showed that peas 

 Ijlanted July 31 and turned under green October 10 were more effective 

 than commercial fertilizers and even horse manure. 



Cowpea vines turned under and cotton meal were more effective for 

 grass, clover, and potatoes on worn cotton soils than commercial fer- 

 tilizers, "showing . . . the soil's need of vegetable matter and nitro- 

 gen." Rotation experiments proved cowpeas a very effective renovating 

 crop for worn cotton soils. 



At the Camden substation a complete fertilizer produced better crops 

 of cotton and Whip-poor-will peas than incomplete fertilizers. Various 

 fertilizers were applied to Spanish peanuts, but the crop was attacked 

 by disease and part of the peanuts rotted, although "the acid phosphate 

 and kainit plats were practically all sound." 



A note is given on the value of soil tests with fertilizers. 



Composition of humus, II. Snyder (Jour. Amer. Chem. Soc, 19 (1897), Xo. 9, pp. 

 738-744). — This is an abridgment of an article in Minnesota Station Bulletin 53 (see 

 page 632). 



FERTILIZERS. 



The decomposition of nitrates by bacteria, A. Sttjtzf.r and 

 H. Jensen (Dent. Landic. Presse, 24 {1897), Wo. 73, p. 665). — Experi- 

 ments are reported which throw light on the behavior of denitrifying 

 organisms in different kinds of manure, to which attention has recently 

 been called by the work of Maercker and Wagner. 1 These experi- 

 ments indicate that these organisms are incapable of reducing nitrates 

 except in the presence of a sufficient supply of assimilable carbon com- 

 pounds to supply energy. If such a source of energy is lacking the 

 nitrates remain unaltered, although the denitrifying organisms may be 

 present in abundance. The fact observed by Maercker that horse 

 manure is more active in causing denitrification in the soil than the 

 manure of sheep or cows is explained by the fact that horse manure is 

 much richer in assimilable carbon compounds than the other manures. 

 The mechanical condition of the horse manure also is such that it is 

 more uniformly and rapidly distributed in the soil than the other kinds. 



Samples of horse and cow manure were shaken up iu water contain- 

 ing a small amount of nitrates, parallel series of tests being made, in 

 oue of which easily assimilable carbonaceous matter was added in the 

 form of glycerin. It was observed that the horse manure without the 

 addition of carbonaceous matter destroyed the nitrates much quicker 



1 Landw. Vers. Stat., 48 (1897), pp. 163-260 (E. S. R., 8, p. 872). 



