Table IV. Year Effect on pH, Total Acidity, Chlorophyll, and Carotene Content of Broccoli (Moist basis) Component Analyzed
1963” Drv matter. ‘7 11 85
1964
11.45
tr
1.99
Chloroph ylls, mg. / l o o grams a
b Total Chlorophylls, reten-
14.23 11.72 5.91 4.00 8.27 5.21 19.43 15.70 6 . 8 4
*
*** ***
***
tion ~
~
~~
96.2 93.3 2.35 * b 95.4 92.3 0.78 92.0 2 17 * Total 94.7 Chlorophylls a to b 2.72 2 . 8 9 1.46 Carotene, mg. / 100 granis 0.88 0.68 5.95 *** a Means of 72 samples. Means of 36 samples. One and three asterisks indicate significance at 5 and O.lCc levels, respecti\ ely. a
coefficients of pigments and plant acids ith available i\eather data i t ere inconclusive for this field study. T-ariable factors such as lag in effects of climatic conditions. plant age, and metabolism were probabl) involved in the failure to establish a relationship bet\\ een climatic conditions and pigments or plant acids. Total chlorophyll and carotene contents of broccoli had highly significant r
it
values for both 1963 and 1964: 0.75 and 0.84, respectively. This relationship \vas reported earlier by Porter and coworkers (70): \vho found a ratio of chlorophyll to carotene in S\viss chard and beet greens of about 24 to 1. In the present study, the ratio for broccoli \vas 22 to 1 in 1963 and 23 to 1 in 1964. Total chlorophyll and ascorbic acid contents of broccoli also ivere highly correlated with a n r value of 0.51 for 1964. Therefore. the higher the chlorophyll content of the broccoli gro\vn in this experiment. the higher were the ascorbic acid and carotene contents of the broccoli. A highly significant T value (-0.74) for total acids and p H of broccoli \vas found in 1963. Ho\vever. the 1964 value (0.15) \vas not significant. T h e relationship benveen total acids and p H of plants is not clear. Highly significant negative correlations bet1veen total acids and p H of lima beans have been found by Graham (I)in the author‘s laboratory. Sideris and Young ( 7 7 ) stated that although p H and acidity in pineapple leaves were in relative agreement, the presence of buffers made perfect agreement impossible. Bonner (2) has stated that a relationship betjveen these two factors is not likely to occur. since p H is determined by pK, plus amounts of free acids and their salts. Total acidity is a measure of only the free acids present.
R e p o l d s . Department of Horticulture. University of Maryland. for supervision of the field plots.
Acknowledgment
ReceiLsed f o r rmiezc June 8, 7965. Acceptrd October 29. 7965. Scientific Article .Yo. d 7197. Contribution a\-o. 36.95 of the M a r y land Agricultural Experiment Station and the Department of Food and ,Yutrition-C‘olZe~ye o/ Home Econoniics cooperating.
T h e author thanks Dale Queen. Betty Lugenbill, and Claire Gott for their valuable technical assistance and Charles
Literature Cited (1) .4ssoc. Offic. Aqr. Chemists, \Vashington. D . C . , “Official Methods of .4nalysis.” 9th ed.. 1960. (2) Bonner. J. F.. “Plant Biochemistry,” Academic Press. New York. 1950. (31 Eheart. 2.1. S.. Gott, C.. Food Trchnol. 19, 867 (1965). (4) Graham. E. L.. master‘s thesis, Cni\rersit)- of Alaryland. College Park, Md.. 1964. (5) Iljin: \V. S..Plant ,Toil 3 , 339 (1951). (6) Lal, K. S . . Subba Rao. M. S., Indian .I. Plcint Physiol. 3, 1-2 (1960). (7) Li. J. C. R.. “Introduction to Statistical Inference.’’ EdLvards Bros., .4nn Arbor, Mich.: 1957. (8) Nelson. E. K., hIottern. H. H., J . A m . C h e m . Soc. 53, 1909 (1931). (9) Obolenskaya. L. I.. Zhadkova, N. D.. I2-c. Akad. .\huk SSSR, Ser. Biol. 28, 108 (1963). Beltz, (10) Porter, T.. \.\’harton, hl. *I., R. hI.. Food R e s . 9, 434 (1944). (11) Sideris, C. P.. Young) H . Y., Plant Physiol. 19, 52 (1944). (12) T a m , R . K., Magistad. 0. C., Z6id., 10, 159 (1935). (13) T’ickery, H . E.: Pucker, G . \I7., It‘akeman. .4. J., Leavenivorth. C. S., C m n . d g i . Eypt. Stu. Bull. 442, 65 (1940). (14) Zuev, L. A . , Khruslova. S. G., Yu. Ch‘ung-Poo. .Vauchn. Dnkl. Vysshei Shkolx, Biol. .Yauki 1963, No. 1. 128; C. A . 59, 5721 (1963).
USE O F F O R M A M I D E
Formamide as a Component of Liquid Fertilizers
A
PROBLEM in production of liquid fertilizers is the limitation on nutrient content imposed by the Xbater required to hold the salts in solution. A lo\v nutrient content adversely affects costs of storing, handling. and shipping the product. O n e major type of liquid fertilizer, nonpressure nitrogen solution, usually is prepared from aqueouu solutions of urea and ammonium nitrate. T h e solubility of the urea and ammonium nitrate limits the nitrogen content of the solution to 32% a t 32’ F.. 30.8% a t 20’ F.. and MAJOR
20
J. A G R . F O O D C H E M .
28.77, at 5” F. ( 7 ) . Some\vhat higher concentrations can be obtained by adding ammonia, but the resulting pressure introduces problems in handling. storage, and application to the soil. A consideration of the properties of formamide led to a study of its suitability as a n agent for raising the nutrient content of liquid fertilizers. Formamide, the acid amide of formic acid. contains 31% nitrogen. It compares favorably iyith urea in greenhouse tests (2). A liquid (f.p. 36” F.) \\-ith a loiv vapor pressure a t ordinary temperatures. it is
THOMAS M. JONES, HARRY T. LEWIS, Jr., and J. G. GETSINGER Division of Chemical Development, Tennessee Valley Authority, Wilson Dam, Ala.
miscible \\ith ammonia and iiater. It is a solvent for many fertilizer salts (3). Salting-out temperatures of various fertilizer salts in formamide. or solutions containing formamide. \L ere measured by cooling a solution of a salt to incipient crystallization. then warming it gently until the salt disappeared. T h e temperature of disappearance \ \ a s taken as a conservative value for the salting-out temperature; this value is a little higher than the actual equilibrium temperature at cr)stallization point. Formamide \vas the practical-grade product. 30.67, S.
yo
Formamide, a liquid at ordinary temperatures and containing 3 1 nitrogen. was used in preparation of nitrogen solutions and liquid mixed fertilizers. Nonpressure solutions containing 34.1 to 35.5% nitrogen and salting out at ' 5 and 32' F., respectively, were prepared from urea, ammonium nitrate, and formamide. Formamide-urea-water solutions containing 31.5 and 33.6y0 nitrogen salted out at 0" and 32" F. Salting-out temperature of urea-ammonium nitrate solution was lowered from 32" to 20" F. by addition of formamide; lowering of nitrogen content was only from 32 to 31.8y0. Formamide arid solutions containing formamide were effective in greenhouse tests. In liquid formulatisons containing 1 1 -37-0 base solution, potassium chloride, and water, additions of supplemental nitrogen as formamide generally gave lower salting-out temperatures than comparable additions as urea and ammonium nitrate.
Nonpressure Nitrogen Solutions Sonpressure nitrogen solutions \\.ere prepared by dissolving various proportions of urea and ammonium nitrate in either formamide or formamide-{vater solutions. \Vith forrnamide alone as the solvent. sol~tbilities of urea and ammonium nitrate \vert? measured over the range S o to 50' F. T h e solubility isotherms and isogranis of nitrogen concentration for the three-component system: ammonium nitrate-urea-formamide, are sho1L-n in Figure 1. l h e amount of jolid (urea ammonium nitrate) added to formamide ranged from 0 to about 52Tj of the total iveight of the three components '1-he maximum nitrogen concentration for ammonium nitrate-urea-formamide solutions that salted out at 50' F. \vas -36%; at 32' F.. 35.57,; a t 5' F.. 34.5%. 'I'he solution containing 35.57, nitrogen and salting out a t 32' F. contained about 57% formamide. 26% urea. a n d 17Vc ammonium nitrate; about half of the nitrogen \vas8 supplied as formamide. T h e nitrogen content of this product. 35.3%. exceeds the 3 2 7 , in a comparable comrnercial urea-ammonium nitrate-\vater solution. For a 5' E'. salting-out temperature. the advantage is even greater--34.5 is. 28.7% nitrogen. Since solutions of formamide and
- SOLUBILITY
ISOTHERMS ( 5 ' TO 5 0 ' F )
- - CI SOONGCREANMTSR AOFT I O NNITROGEN
+
__
CO ( :4 r i 2 ) 2 /
- -
--
Figure 1. 50
-
\
V
v
\
v
,
System NH4N0,-CO(NH,)~-HCONHz
-
40-
2 30I-
3
0
& 20 Table 1. Addition of Formamide to Commercial Urea,-Ammonium Nitrate-Water Solution." Effect on Salting-Out Temperature and Nitrogen Content Formamide,
Wf.
%
0 0 2 0 4 8 '4
Tofaf Nifrcgen,
%
Salting-Ouf Temp., F.
'
32 0 32 30 8" 20 32 0 30 31 9 26 31 9 24 9.1 31 . 9 21 10.7 31.8 20 13.0 31.8 22 16.31.8 23 Composition: 45 ammonium nitrate, 35( urea. 20''; water. Il'ater added to lower nitrogen content from 32 to 30.8";.
"
55
60
65 70 75 FORMAMIDE, WT %
85
80
Figure 2. Salting-out temperatures of forrnamideurea-water solutions
water have lo\ver freezing points rhan either component. tests \Yere made of the effects of formamide additions on nitrogen content and salting-out temperature of a urea-ammonium nitrate-\\ ater solution corresponding to the commercial nonpressure solution containing 327, nitrogen [designation 320 (0-45-35)l. T h e results in Table I sho\v that the VOL.
formamide loivered the salting-out temperature a t the eutectic (about 11% formamide) from 32' to 20' F. \vith only a slight decrease in nitrogen content (from 32 to 31.8%). H a d \vater been added to obtain a salting-out temperature of 20' F.. as is customar>-. the solution \vould have contained about 30.87, nitrogen. In other tests. \later \\-as
14, NC'.
1, J A N . - F E B .
1966
21
Table I I .
added to a 367c N solution (20 parts ammonium nitrate, 28 parts urea, a n d 52 parts formamide) to lower the nitroT h e salting-out gen content to 34%. temperature was lojvered from 50' to 30' F. Other nonpressure nitrogen solutions ivere prepared by dissolving in formamide various proportions of ureaivater mixtures containing 75: 85:or 9070 urea-the range of concentration from commercial urea plants before the evaporation step. T h e data in Figure 2 indicate that raiv solutions from urea plants ma)- be mixed ivith formamide to yield solutions that contain 31.7 to 34.1% nitrogen and that salt out a t 0 ' to 50' F. Solutions salting out a t 32' F. contained 32.2 to 33.6yG nitrogen. For the 75, 85: and 90Oc urea-ivater solutions. the respective eutectic points \\-ere l o >9'. and 12' F . ; formamide contents of the eutectic solutions Ivere 76. 78, and 80%total nitrogen contents, 31.7. 32.6. and 32.97,. T h e eutectic solutions all had higher nitrogen contents and lo\ver salting-out temperatures than comparable commercial solutions prepared either from urea and ivater or from urea, ammonium nitrate, and water. T h e effect of additions of ammonium nitrate on the salting-our temperature of
Addition of Ammonium Nitrate to Formamide-Urea-Water Mixtures-Effect on Salting-Out Temperature Components, W t .
Ammonium nifrote
Total Nitrogen,
%a
Ureah
Solting-Ouf Temp., F.
%
HrOC
Formamide
65.0 (57.5) 3.5 34.6 0 31.5(42.5) 63.1 (55,s) 3.4 34.6 2 . 9 12.9) 30.6 (41.3) 8 . 3 (8.41 28.9 (38.9) 59.6 (52.7) 3.2 34.6 58.5 (51.7) 3.2 34.6 9 . 9 (10.0) 28.4(38.3) 13 8 (13.9) 2 7 . 2 136.6) 5 6 . 0 149.5) 3.0 34.6 53 3 (47 1 ) 2 9 34 6 18 0 (18 2 ) 25 8 (34 - ) 20 0 (20 2 ) 25 2 ( 3 3 9 ) 52 0 (45 9 ) 2 8 34 7 50 0 (44 2 ) 2 7 34 7 23 1 ( 2 3 3 ) 24 2 (32 5 ) 0 3 5 , l (46.7) 6 1 . 0 (53 3) 3.9 35.0 13.0 (13.0) 30.6(40.7) 53.0(46.3) 3.4 35.0 18.0(18.0) 28.8(38.3) 50.0(43.7) 3 2 35.0 28.1 (37.4) 48.8(42.6) 3.1 35 0 20.0 (20.0) 20.6 (20.6) 27.9 (37.1) 48.4(42.3) 3.1 35 0 2 1 . 9 (21 9 ) 2 7 . 4 136.4) 47.7 (41.7) 3.0 35 0 23.1 (23.1) 27.0(35.9) 46.9 (41.0) 3.0 35.0 Parenthetical figures show per cent of total nitrogen supplied by component. L-rea-water mixture (90:; urea). c From urea solution.
67 63 53 48 41 32 35 42 84 57 46 41 40 42 44
$1
Table I l l .
Solutions for Corrosion Tests ?&
ComDosition. Wt. Formamide
Ammonium nitrafe
Ureo
Total
N,
Woter
2.9
Table IV.
%
34.0
Effect of Formamide on Salting-Out Temperature of Liquid Mixed Fertilizers
Formulation, W t . ~
Fraction o f Supplemenfury N from Formomide,
% ~
Ammonium nifrate
%
Observed
a
Water
16.1 18.4 16.1 20.7 16.9 16 9 18.4 23.0
53 9 47. 3 41.9 40.8 34.9 36.2 35.2 34.1
27.1 27.1 27.1 27.1
15.8 15.8 15.8 15.8
5.3
27.8 33.4 34.3 39.0
50.7 40.9 32.1 30.9
13.5 16.2 19.0 19.0
8.0 9.5 11.1 11.1
44.1
34.5
13.5
7.9
2.5
29.6
56.8
11.1
100
20
8
12-1 2-6 10-10-5 3 : 2 : 1 Ratio
27.6 23.0
30.4 42.0
32.5 27.1
9 5 7.9
100 100
- 10 -14
34
12-8-4 6 : 5 : 4 Ratio
31.4
40.5
21.7
6.4
...
100
- 18
30
... 1.5
100 84
40 34
69 69
2.9
82
19
70
Urea
1 : 1 : 1 Ratio
--/ - I
I -
8-8-8 9-9-9 9-9-9 10-1 0-1 0 10-1 0-1 0 10-10-10 10-10-10 2 : 1 : 1 Ratio 10-5-5 12-5-6 14-77' 14-7-; 3 : 1 : 1 Ratio 15-5-5 1 : 3 : 1 Ratio 7-21-2 : 2 : 1 Ratio
J. A G R . F O O D C H E M .
-3
2 28 34 66 72 68 70
30 44 58 58 -1 -1 -1 71
.
100 100 88 100
-10 - 2' 12 29
32 50 69 69
...
100
1.5
12-1 0-8 29.5 30.8 12-1 0-8 24 9 31.9 1 4 : 9 : - Ratio 14-9-30.7 29.5 23.8 11.2 * TV.1 ammoniated superphosphoric acid. h . i l l supplementary nitrogen from urea-ammonium nitrate solution ( 5 )
22
100 100 78 100 74 74 80 100
...
2.0
4.0 1 5
, . .
...
... ...
...
2.0
1.5
...
,
...
1.9
