ct of Carbon erties of
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EFFECT ON SOIL TEMPERATURES whose surface area, structure] etc., JOHN N. EVERSON Carbon has decided effects on are well defined (2, 8, 9), should the temperature, texture, salt University of Massachusetts, Amherst, M U S S . remove much of this uncertainty retention, and moisture retenby showing which effects are due tion of soils into which it i s inJAhlES IR. WEAVER t o blackness and fine particle size corporated. Since these variGodfrey L . Cabot, Znc., Boston, M u s s . vc-ithoutnutrient value. ables may have a major influA cooperative project between ence on the growth of plants. a the LIassachusetta State Bsperinient Station and Godfrey L. study was made of the effect of carbon black on soils and on Cabot, Inc., was therefore arranged in 1944, and work was carried plant growth. The present paper reports effects of carbon on continuously through 1947. Field studies and laboratory tests black incorporation on temperatures of soils. Temperature were carried out a t the experiment station a t Amherst. The measurements were made for more than a year on different general purpose \vas to investigate the primary effects of carbon portions of the same plot, part of which had been treated black on soils and the secondary effects on growing crops. The with 4000 ponnds of carbon black per acre. hleasurements objcct of the present article is to describe the tests arid conwere made a t the surface and 2 inches beneath the surclusions concerning the effect of carbon black on soil temperature. face of the soil. Data are included for months when Literature on the tempcrature effects of carbon addition to effects might be important to plant growth. Results soils is sparse. I n the course of experinients on the comparative indicate that, a t the surface and 2 inches deep in the loss of seedlings 011 burned and unburned surfaces, Isaac ( 4 ) soil, addition of carbon increases maximum and minimum reported maximum surface temperatures on a “bldck (soil) temperatures attained, and increases time available €or surface” to be 7’ to 18”F. hotter than temperatures on a “yellow growth of plants. (soil)surface,” over the 5 days reported. Rodale ( 7 )stated that “as between a dark and a yellowish soil there may be a teiiipeiature This matter of heat and light absorption is difference of 8-10’. acts as a plant nutrient, is itself digested by plant roots, or has any otliei direct effect on plants. However, since carbon black is & nearly perfect black body and is a colloidal material with high adsorptive capacity, it could have a decided effect on soil temperature and also on the texture, salt retention, and moisture retention of the soils. The growth of plants could be greatly afTected by major changes in these properties of soils. The use of carbon in agricultural applications has been suggested and investigated in the past, Both charcoals and Scotch soot have been used to aid growth of plants. Howm e r , t h e types and nature of these charcoals were not accurately defined, and Scotch soot is known t o contain appreciable concentrations of plant nutrients in the form of contaminating salts. These factors may have contributed t o the uncertainty which exists regard, 1 i I I I ing the value of finely divided N LY AdG SEPT. APRIL MAY ACE JULY carbons in agriculture. Tests 1944 1945 with carbon black, a finely diFigure 1. Comparison of Maximum Temperatures of Carbon-Treated and Untreated vided form of pure carbon Soil a t the Surface and 2 Inches Deep
0 EVIDEKCE is available to indlcate that carbon black
1798
70
o
24 hours a day, except for power failures and other unavoidable circumstances, from June 20, 1944, until July 23, 1945. Only data from the spring and summer months are included here. These are the months when a n increase in soil warmth could be of help to plants and crops. D a t a from five of the therniocouples are included. Their locations were as follows: one in ventilated shaded air 4 feet above ground, one in untreated soil at surface of soil, one in untreated soil 2 inches deep in the soil, one in carbontreated soil a t the surface of the soil, and one in carbon-
= CARBON -TREATED-SURFACE
= UNTREATED-SURFACE
60-
ir: 0
w 3
$50.
2
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I 0 = CARBON-TREATED SOIL :‘’D;:P 8 = UNTREATED SOIL
showed no significant variations in temperatures from those described here. Still other thermocouples showed that 1000 and 2000 pounds of
50
i i
tests. This black has a surface area of about 150 square meters per gram, as measured by nitr:gen adsorption, and a n average particle diameter of about 250 A,, which is in the colloidal range. E3 channel black is about 95% carbon and 5% volatile matter (carbon, oxygen, hydrogen). Other carbon blacks are as much a s 99.5% carbon. The soil was a Merrimac h e sandy loam, containing 3.5% clay, and located on the grounds of the University of Massachusetts. The soil had been treated with 7-7-7 fertili~erat the rate of 200 pounds of nitrogen per acre. T h e ground had aslight eastern slope. The tested soil was kept free of crops or weeds and fully exposed to weather; water was diverted by ditches dug for t h a t purpose. “Untreated soil” refers t o soil with fertilizer present but not treated with carbon. I n these tests E3 black was mixed into parts of the soil t o a depth of approximately 2 inches a t the rate of 4000 pounds per acre. Assuming an acre to contain 2,000,000 pounds of soil in the top 7 inches, an average figure widely used (S),the concentration works out t o be about 0.7700. At this concentration carbon black darkens the soil. “Carbon-treated soil” refers t o soil with carbon present in this amount, as well as the fertilizer already mentioned. Temperature was measured with a Leeds & Northrup Micromax recording potentiometer. The instrument recorded temperatures about four times a n hour a t each thermocouple, for
Soil 2 Inches Deep Soil a t Surface UnCUnCShaded treated treated treated treated Air MAXIXUMTEMPERATURES
F. July 1944 Aug. 1944 6-i7 lk5 18-31
p$i i:jt May 1945 :U,y:
:!::,
1945
2;;1-5, . 11994444 18-31 se~;a1~g44
April 1945 May 1945 june 1945 1-231
1946
F.
* F.
F.
F.
86.7 93.7 89.7 99.5 77.8 70.0 70.8 79.2 83.9
82.4 83.7 80.1 88.8 72.3 64.6 66.2 76.4 79.1
F.
MINIMUM TEMPERATUREB F. F. F. a F.
61.2 62.9 59.4 68 1 55.1 47.9 52.9 58.6 83.1
61.9 63.4 60.3 67.9 55.4 48.8 53.5 59.5 65.0
F.
’ F.
25.5 30.8 22.7 22.1 17.9 20.6 20.8
25.7 28.6 23.2 22.2 20.9 26.8 21.4
62.4 63.8 60.2 69.3 56.3 49.3 52.9 58 7 63.4
62.2 63.7 60.8 68.0 55.9 50.4 53.5 59 5 65.0
57.9 60.0 56.7 65.0 52.7 42 8 46.8 52.8 57.6
TEMPERATURE R A N Q E B O
July 1944 Aug. 1944 Sept. 1944
April 1945 May 1945 June 1945
July 1-23,1945
O F .
18.5 22.4 17.1 16.8 15.9 18.4 16.7
OF.
OF.
21.3 23.7 20.6 17.3 19 9
24.5 23.7 19.6 21.8 19.4 23.6 21.5
24.2
19.6
1800
Vol. 41, No. 8
INDUSTRIAL AND ENGINEERING CHEMISTRY
cluded the hottest days of the whole test period. A white deposit, which tests proved to be an accumulation of solid salts, covcred the carbon-treated area during these days, This whitening must have reduced the heat intake from the sun of the normally black carbon-treated area. The period is therefore considered separately. Such a whitening effect did not rccur until the hot dry days of .%ugust 1947. The results of the measurements are discussed first in terms of maximum and minimum temperatures achieved a t the various thermocouples, and then in terms of the relative areas of temperature vs. time curves plotted from t h e daht.
I
I
I I
AVERAGE DAILY TEMPERATURES
Table I presents monthly averages of maximum daily temperatures for the five stations for the months of JulyI August, and September 19+4, and April, May, June, and July 1945. Figure 1 compares the average maximum temperatures of the untreated and carbon-treated soils, a t the soil surface and 2 inches below the surface, for these months. Table I also gives monthly averages of minimum daily temperatures for the five stations for the same months. Figure 2 compares the average minimum temperatures of +ULY AUG. SEPT. APRIL MAY JUNE JULY the untreated and carbon1944 1345 treated soils a t the soil surFigure 3. Comparison of Daily Temperature Ranges of Carbon-Treated and Untreated Soil at the Surface and 2 Inches Deep face and 2 inches below the surface, for these months. Daily temperature range is here defined as the maximum daily daily maximum or minimum m as used as the hourly reading for temperature reading minus the minimum daily temperature the hour closest to which it occurred. reading. Table I shows the average daily ranges for each of the These data were then replotted on a chait of more workable five stations for the seven months. Figure 3 compares average dimensions, and the daily area of the temperature-time curve daily temperature ranges of carbon-treated and untreated soils was measured with a planimeter. Little biological activity is a t the surface and 2 inches below the surface, for these months. believed to go on below 40 O to 43' F. ( 1 , 5 , 6 ) so , 42' was chosen as a convenient base line. These areas were taken only on the four SOIL WARMTH soil temperatures. Warmth is defined as state of being warm, so the area of a Results of this analysis are presented in Table 11, which shows curve of temperature u s . timc can be considered as being profor the four soil stations the monthly totals of area of the temportional t o soil warmth. As an indication of the effect perature-time curve over 42" F., recorded as O F.-hours. Since of carbon on soil warmth, areas of temperature-time curves for August 6 to 17, 1944, was an exceptional period, totals for it axe these months were studied. D a t a were converted t o tabular form included separately as well ah combined with those of the rest by taking readings from the original chart once every hour. Since of the month. The total for the seven-month period is also the hlicromax did not record at exactly %-minute intervals, the included for each station. Figure 4 presents some of the same point nearest each hour a a s used as the reading for t h a t hour. data converted t o read directly in per cent increase of soil warmth An exception was made when the maximum and minimum daily (area of temperature-time curve) caused b y carbon addition. temperatures were not the point closest t o any hour; then the Surface data are on the basis of untreated soil surface warmth;
INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
August 1949
1801
than those of the untreated soil surface. 4. Minimum daily temperatures reached by carbontreated soil 2 inches below the surface were very slightly higher on the average (0.5 F. j than those in the untreated vi > soil 2 inches below the surface. During April, &fay, June, and July 1945, this aver$ 4 age was 0.6' t o 1.6' F. higher; a during July, August, and 5 September 1944, this average was 0.1" t o 0.4' F. lower. 5 . Maximumdaily temperatures were higher on the average and minimum daily temz peratures were lower on the average a t the surface of soils than 2 inches below the surface-that is, the surface went t through a wider range of 3 temperature than did the 2inch depth. This held for both carbon-treated and unJULY AUG. SEPT APRIL JUNE JULY 1944 1945 treated soils but was more Dronounced with carbon-treated Figure 4. Increase in Soil Warmth Caused by Addition of Carbon Black at Soil Surface soils. and at 2-Inch Depth 6. Daily maximum shade air temperatures were lower on the average (5' t o 7" F.) than maximum temperature of any soil, in the field. Daily minidata at 2-inch depth are on the basis of untreated soil warmth mum air temperatures were also lower on the average (4' t o 7 'F. ) at 2-inch depth. than daily minimum soil temperatures. Thls is reasonable since The increase shown in the area of the temperature-time curve the air is heated mostly by the soil and, therefore, never reaches over 42" F. allows more time for biological activity in carbonsuch a high temperature. 7. During May, June, and July 1945, the carbon-treated soil treated soils. Also, biological activity, like chemical activity, 2 inches deep reached maximum temperatures higher than those is considered t o be doubled by each 18"F. increase in temperature achieved by t h e surface of t h e untreated soil. over 40" to 43" F. ( I , 5j, up to temperatures of plant destruction 8. Carbon-treated soils had a slightlv wider averacre dailv by burning. Thitj increase in soil warmth (area of temperaturerange of temperatures than did untreaied koils, both a t the surfack (1.2'F.) and at 2-inch depth (2.4" F.). time curve) would therefore not be proportional to the increase 9. The area of t h e temperature-time curve over 42" F. was of biological activity to be expected from the carbon addition. larger for carbon-treated soil surfaces than for untreated soil surSince much of this increase in area is at higher temperatures faces, for every month tested except August 1944. This can be considered as an increase of soil warmth. than were achieved by untreated soils (as maximum temperature 10. The area of the same curve was also larger for carbondata of Table I show), biological activity would probably intreated soils at 2-inch depth than for untreated soils a t 2-inch crease by more than the percentage increase in area of the temdepth for every month tested, except for August 1944. perature-time curve. 11. During four of the seven months of the tests, the area of the temperature-time curve was greater for carbon-treated soil a t 2-inch depth than at the surface of the untreated soil. CONCLUSIONS 12. The temperature-time curves were measured over 42 O F. Since little biological activity goes on below 42 ' F., conclusions 9 1. During the 7 summer months reported, maximum daily and 10 show t h a t more time was available for biological activity temperatures reached by carbon-treated soil surfaces, in the field, in the carbon-treated soil than in the untreated soil. mere slightly higher on the average (2 O F. j than maximum teni13. Since biological activity generally doubles with a temperatures of untreated soil surfaces. An exception was August perature increase of about 18' F. (above 42 ' F. j, and since much 1944, the hottest month of the test period. of the increase in area of t h e temperature-time curve is at tem2. Maximum daily temperatures reached by carbon-treated peratures hi her than those achieved by untreated soils (conclusoil 2 inches below the surface were higher on the average sions 1 and 27, biological activity should increase in carbon-treated (3.4 F. j than those reached by untreated soil 2 inches below the soils by more than the increase in area of the temperature-time surface. curve. 3. Minimum daily temperatures reached by the carbontreated soil surface were slightly higher on the average (0.8" F.) 8
YI
L2
%
LlTERATURE CITED
(1) Aikman, J. M., and Brackett, G. L., Proc. Iowa Acad. Sci,, 51,
TABLE11. TOTALAREAS O F T3MPERATURE-TIME CURVES 4BOVE 42" F. (IN F.-HOURS) Soil a t
UnJuly 1944
Aug. 1944 1-5, 18-31 6-17 Sept. 1944 A ril 1945 d a y 1945 dune 1945 July 1-23, 1945
treated 22,024 22,909 11,824 11,085 15,505 10,729 13,200 17,876 14,854 ~
Total
L17.097
Surface
Soil 2
'
Ell::
Ctreated 21.850 21,987 11,602 10,385 15,521 11,150 13,074 17,724 14,944
Covered by Data 733 701 413 288 685 714 728 703 514
114,584
116,250
4778
___
___
120,215
Inches Deep
treated 21,349 22,198 11,529 10,669 15,281 10,555 12,890 17,715 14,596
Un-
Ctreated 22,777 22,816 12,036 10,779 15,753 11,505 13,710 18,426 16,229
__
__
147-56 (1944).
(2) Duffy, G. J., Godfrey L. Cabot Tech. Bull., 11, No. 1 ( 1 9 4 7 ) .
( 3 ) Gustafson. A. F.. "Soils and Soil Manaaement." D. 43.New York. MoGraw-Hill Book Co., 1941. (4) Isaac, L. A., J.Forestry, 28, 569-71 (1930). (5) Livingstone, B. E., and Shreve, F., "Distribution of Vegetation in U. S. as Related to Climatic Conditions," Carnegie Inst. of Washington, D. C., 1921.
Lundeghrdh, H., "Environment and Plant Development," by E. Ashby, London, Edward Arnold & Co., 1931. (7) Rodale, J. I., "Pay Dirt," New York, Devin Adair, 1946. (8) Smith, W. R., Am. I n k Maker, 2 5 , 3 4 - 4 1 , 4 7 (May 1947). (9) Sweitzer, C. W., and Goodrich, W. C., Rubber Age ( N . Y . ) , 55, (6)
469 (1944).
R E C E I V ~Octobes. D 15, 1947.
