July 7, 1921 



The Florists' Review 



17 



uji«jjitvji4y^ i Miai«tyiiMiiLtiit^ity ^M^ 



iJtiS^l^l^S^aiS^l^Jl^l^I^l^liSiJl^i^ 



FORMS OF PLANT FOODS 



r^^s^rrstiririvirirsfirrsvir/stirirsvirrsvir/t 



WSjfly^fly^tlii^BTTtltT^tltTTilW^lffTtliT^^ 



HOW TO KNOW FEBTILIZERS. 



Finding Value to Florist. 



Numerous analyses of plants and 

 soils, together with tests carried out 

 under controlled conditions in all parts 

 of the country, have shown that, as a 

 rule, only three chemical elements of 

 soil are found lacking to an extent that 

 affects the growth of plants. These 

 elements are nitrogen, phosphorus and 

 potassium. Occasionally calcium and 

 sulphur may be deficient also, but these 

 deficiencies have not been found as 

 widespread as have been the deficiencies 

 of the above-named three elements. 

 Commercial fertilizers, then, to be of 

 value must contain one or more of these 

 elements which experimental study has 

 found to be lacking in soils. In other 

 words, the value of any commercial 

 fertilizer depends upon the available 

 quantity of these three necessary ele- 

 ments which it contains. 



In order that the purchaser may know 

 the quantity, manufacturers place upon 

 the label a guaranteed statement which 

 indicates the composition of the ferti- 

 lizer. The guarantee states, as a rule, 

 the minimum amount of the constitu- 

 ent contained in the material. The pur- 

 pose of the guarantee, of course, is to 

 protect the consumer. It is of service 

 to the manufacturer, too, in that it 

 tends to keep down the number of low- 

 grade brands of fertilizers, which would 

 naturally compete with the higher and 

 better grades. 



Beading the Guarantee. 



Since the guarantee is for the pur- 

 pose of protecting the consumer from 

 the purchase of useless substances, it is 

 essential that the consumer be able to 

 read intelligently the facts conveyed in 

 the guarantee. Guarantees are confus- 

 ing sometimes to the purchaser; they 

 are misleading sometimes. The fact 

 that they may be misleading does not 

 necessarily prove that they are false or 

 illegitimate. The guarantee may be in 

 accordance with the facts, but the terms 

 used in the guarantee may be such that 

 their interpretation is difficult. It is 

 this point which I wish to clear up and 

 my endeavor is to point out the mean- 

 ing of the terms used and the method 

 of interpreting a printed guarantee. 



Three Tjrpes of Fertilizers. 



Fertilizers are, from the standpoint 

 of composition, of three types. These 

 types are the nitrogenous, or those which 

 contain a large per cent of nitrogen; the 

 phosphatic, which contain a high per- 

 centage of phosphorus; and the potas- 

 sic, so called because of the high con- 

 tent of potassium. 



The nitrogen occurs in commercial 

 fertilizers in three different forms, 

 namely, (a) nitrate, (b) ammonia, and 

 (c) organic nitrogen. The nitrate form 

 is soluble in water and immediately 

 available to the plant. The ammonia 

 must be converted into the nitrate form 

 before it is available to the plant, but 

 it becomes so quite rapidly under fa- 

 vorable conditions of the soil. Organic 

 nitrogen also must be converted into an 



By DR. P. A. LEHENBAUER. 



available form before it can be taken 

 up by plants. Some forms of organic 

 nitrogen — for example, that found in 

 dried blood, tankage and cottonseed 

 meal — are converted readily, under fa- 

 vorable conditions, into the nitrate form 

 by means of bacteria. Other forms, how- 

 ever — for example, that contained in 

 hoof, leather waste, and much of that 

 contained in manures — are converted 

 less readily. 



Forms of Nitrogen. 



A nitrogenous fertilizer may contain 

 the nitrogen in either or all of the three 

 forms; that is, the nitrogen may be 

 present as nitrate, as ammonia, or in 

 organic form. Other elements, of course, 

 are present in addition to the nitrogen; 

 a fertilizer never consists of pure nitro- 

 gen. Only a variable percentage is 

 nitrogen. The important thing, then, 

 is to know the percentage of nitrogen 



Greater use of commercial 

 fertilizers by florists necessitates 

 more definite knowledge of 

 their composition and their 

 value to soil for flower plant 

 crops. Methods for calculating 

 the contents given on manufac- 

 turers' labels enable florists to 

 know just what the fertilizers 

 contain in the way of food for 

 their plants. Intelligent use of 

 them will assist in producing 

 the stock of high quality that is 

 now the aim of all growers. 



in the fertilizer. Now, this percentage 

 of nitrogen may be expressed in several 

 different forms. We will assume that a 

 fertilizer contains three per cent nitro- 

 gen. This may be expressed in the 

 guarantee as "Nitrogen 3%," as 

 "Nitrogen equivalent to 3.64% ammo- 

 nia," or as "Nitrogen equivalent to 

 14.1% of ammonium sulphate." If all 

 three of the statements occur on the tag 

 it could readily enough be inferred that 

 the fertilizer contains 20.73% nitrogen, 

 which, of course, is not true. The fer- 

 tilizer contains only three per cent 

 nitrogen and no more. The statements, 

 however, are justifiable because, as said 

 above, the nitrogen does not occur as 

 pure nitrogen, but instead in compound 

 form, such as ammonium sulphate, etc., 

 and the statements, therefore, indicate 

 the form in which the nitrogen occurs 

 in the particular fertilizer. How, then, 

 are we to determine the percentage of 

 nitrogen if it is given in the equivalent 

 form on the tag? 



The following method may be used 

 for calculating the per cent of nitrogen 

 from the per cent of ammonia or am- 



monium sulphate and vice versa: In 

 order to get the per cent of ammonia 

 when the per cent of nitrogen is given, 

 multiply by 1.215. If the per cent of 

 ammonia is given, in order to find the 

 per cent of nitrogen multiply by 0.8224. 

 Stated again in slightly different form, 

 in order to convert ammonia into its 

 equivalent of nitrogen, multiply the 

 percentage of ammonia by .82, or what 

 amounts to the same thing, divide by 

 the factor, 1.215. Ammonia is approxi- 

 mately eighty-two per cent nitrogen and 

 one part of the nitrogen is approxi- 

 mately equivalent to 1.215 parts of am- 

 monia. In order to calculate the per- 

 centage of nitrogen in ammonium sul- 

 phate, multiply by 0.215. 



Forms of Phosphorus. 



Phosphorus occurs in various ferti- 

 lizer materials, such as rock phosphate, 

 acid phosphate, bone meal, treble super- 

 phosphate, etc. In these fertilizers the 

 phosphorus is in combination with cal- 

 cium (or lime). In order to be avail- 

 able to the plants, these compounds of 

 phosphorus and calcium must be soluble 

 or made soluble. The acid phosphate, 

 for instance, is manufactured by mix- 

 ing approximately equal quantities of 

 raw rock phosphate and strong sulphuric 

 acid, in the process of which a large 

 part of the phosphorus is made into a 

 soluble form. For convenience, the 

 phosphorus is expressed as per cent ol 

 "phosphoric acid." That part of the 

 phosphoric acid which is soluble in water 

 and is immediately available to the 

 plant during its period of growth is 

 known as "water soluble." Some of 

 the phosphoric acid which is insoluble 

 in water is soluble in a certain strength 

 of ammonium citrate and is known as 

 "citrate soluble." This phosphoric acid 

 also is available to the plant. The re- 

 maining "insoluble" phosphoric acid 

 becomes available to the plant only very 

 slowly. 



Analysis of Phosphate. 



The analysis, then, of a phosphatic fer- 

 tilizer, as shown on the manufacturer's 

 tag, may indicate several facts; namely, 

 the available, the water soluble, the 

 citrate soluble, the insoluble, the equiva- 

 lent to bone phosphate, and the total 

 phosphoric acid. In calculating the 

 value of these we may take the sum of 

 the "water soluble" and the "citrate 

 soluble" and consider it the total avail- 

 able phosphoric acid. The insoluble is 

 the amount obtained by subtracting the 

 total available from the total phosphoric 

 acid. The value of the fertilizer is de- 

 termined, of course, by the per cent of 

 available phosplioric acid. The follow- 

 ing table indicates the method of con- 

 verting the percentage of one form of 

 phosphorus into any other: 



To convert Into eqiiivn- Multiply 



ppr pent of lent of by 



Phosphoric acid pliosphorus 0.44 



Phosplioric acid bone phosphate 2.2 



lione phosphate phosphorus 0.2 



Kone phosphate phosphoric acid 0.46 



Phosphorus phosphoric acid 2.3 



Phosphorus bone phosphate 5.0 



If, for example, bone meal is guar- 

 anteed to contain from forty-five to 

 forty-eight per cent of bono phosplcite, 

 [Continued on page 36.] 



