ATGUST SO, 1900. 



The Weekly Florists' Review. 



399 





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Entrance to the Phipps Conservatories, Schenley Park, Pittsburgh, Pa. 

 [Erected by Lord & Burnham Co., Nsw York.] 



known th.;t nitrates when onee forme 1 

 are not retained by the soil, lilve pot- 

 ash or phosphates, but they are either 

 absorbed and utilized as food by plants 

 or are washed out of the soil by drain- 

 age water. In some experiments at 

 Rothamsted relating to rainfall and 

 drainage, it was found that over the 

 twenty harvest years. 1877-8 to 189(5-7, 

 there was an average annual loss of 

 nitrogen as nitrates in the drainage of 

 35 pounds through twenty inches ieep 

 of soil, and 34 pounds through sixty 

 inches deep of unmanured and un- 

 cropped soil, correspoi.ding to ;in an- 

 nual average loss of nearly 2 cwt. of 

 nitrate of soda per acre. Not mor.> 

 than 5 pounds of this nitrogen wouil 

 be contributed annually by the rain- 

 fall; the remaining .30 pounds would 

 be obtained by the o..idation of ths 

 humus matter of the soil, whicn is thus 

 gradually being reduced by the agency 

 of micro-organisms. The decomposi- 

 tion of humus gives rise to carbonic 

 acid. A solution of this can dissolve 

 certain substances which are impor- 

 tant as plant food, such as phosphates, 

 lime, and magnesia compounds which 

 are insoluble in n.itural water. If the 



soil is lacking in humus growing 

 plants will find less soluble mineral 

 food. We may illustrate this fact by 

 one of the Rothamsted experiments en 

 a four-course rotation of crops which 

 has been going on since the year 1S4S. 

 The present season (1899) has grown 

 a crop of wheat which is the fourth 

 crop of the thirteenth lourse, the por- 

 tion to which reference will be mad? 

 has had no manure during the whole 

 Of that period, so that the land has 

 grown fifty-two crops in rotation with- 

 out manure. In 1898 one portion of 

 the field was left bare fallow, that is, 

 without a crop, the other portion grew 

 a crop of beans. The produce of wheat 

 in 1899 after the fallow was 26:m busii- 

 e!s per acre of 62 pounds weight, the 

 produce after the beans was 30^/4 bush- 

 els per acre of C3 pounds weight. There 

 was a gain of total produce (corn and 

 straw! of 477 pounds from the beans 

 over the fallow. That is to say, the 

 bean crop, by virtue of the nodules 

 upon the roots, had assimilatsd a cer- 

 tain amount of nitrogen from the at- 

 mosphere, and the humus left over 

 from the residue of the bean roots in 

 the soil had combined with the exist- 



ing minerals of the land, and thus 

 yielded the increase of crop mentioned. 

 There h;ul also taken place, doubtless, 

 some nitrification of the organic mat- 

 ter (humus) by the action of the mi- 

 cro-organisms. The effects of humus 

 on the capacity of the soil to retain 

 water and withstand the evil effects of 

 drought have been found to be very 

 marked. It will thus be seen (.hat the 

 humus cf soil is a constant source of 

 nitrogenous plant food, and that its 

 great value resides no, only in Its in- 

 creasing of the moisture-holding ca- 

 pacity of the land, but in its nower of 

 liberating the mineral element, phos- 

 phoric acid. 



IF YOU have any surplus stock to 

 offer to the trade remember that you 

 can sell it most quickly and cheaply 

 through an offer in the Review's Clas- 

 sified Plant Advs. 



THE REVIEW'S Classified advs. en- 

 able you to find with the least possi- 

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