Jan., rgI8
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
REACTION OF HAWAIIAN SOILS WITH CALCIUM BICARBONATE SOLUTIONS, ITS RELATION TO THE LIME REQUIREMENTS OF DETERMINATION OF SOILS, AND A RAPID APPROXIMATE METHOD FOR THE DETERMINATION OF LIME REQUIREMENTS OF SOILS1 By MAXWSLL 0.
JOHNSON
Received October 1. 1917
The importance of liming for t h e maintenance of soil fertility is so well recognized t h a t a number of methods for determining the lime requirements of soils have been proposed. Most of these methods are based on reactions which do not parallel those occurring in t h e field. Whether lime is applied as oxide, hydroxide or carbonate t h e main reaction of t h e limed soil would appear t o be with calcium bicarbonate in solution. Hutchinson and MacLennan2 and MacIntirea have proposed methods for determining t h e lime requirements of soils using calcium bicarbonate solutions. I n t h e Hutchinson-MacLennan method, 10-20 g. of soil are shaken for 3 hours with zoo t o 300 cc. of an approximately 0 . 0 2 N bicarbonate solution. After filtering, a portion of the filtrate is titrated with 0.1 N acid, using methyl orange as an indicator t o determine the calcium carbonate absorbed by t h e soil. I n the MacIntire method I j o cc. of bicarbonate solution are evaporated with I O g. of soil t o a thin paste and the excess calcium carbonate estimated by the COz liberated with acid. An investigation has been made of the reaction of typical Hawaiian soils with calcium bicarbonate solutions under various conditions. As a preliminary announcement of results, it may be stated t h a t t h e extent of the reaction has been found t o depend on the usual factors influencing absorption, i. e., the nature of the soil, the concentration of solution, t h e period of contact and the ratio of soil t o solution. This would account for the variations in results obtained by the Hutchinson-MacLennan and by the MacIntire methods when slight variations are made in the methods of pr~cedure.~ The absorption by the soils from calcium bicarbonate solutions increased with t h e period of contact and approached an equilibrium. As the concentration of the bicarbonate solution was decreased, t h e absorption decreased in amount b u t an increasing percentage of the total calcium carbonate in the bicarbonate solution was absorbed. This would show t h a t by using solutions o f decreasing concentrations or b y using increasing weights of soil a point would be reached where absorption would be practically complete under prolonged contact sufficient t o insure equilibrium of t h e soil with i h e solution. The total amount of calcium carbonate (calculated as per cent of the weight of the soil) in the solution at and below whose concentration absorption by a given soil is complete, would appear t o express a definite absorptive capacity for t h a t soil. This definite absorptive capacity has been designated 9
1 Published
by permission of the Secretary of Agriculture. J . Agr. Sci.. 111 7 (1915). 75-105.
4
See Jour. Assoc. Off. Agr. Chem., 3 (1917), 133-149.
* TITISJOURNAL,
7 (1915), 864-867.
31
the “minimum absorption.” An amount of calcium carbonate slightly in excess of t h e minimum absorption would appear t o be t h e correct application t o make in t h e field as being sufficient t o insure a slight alkaline reaction. I n theory, t h e lime requirements of a soil by t h e Veitch method‘ should lie very slightly above the minimum absorption, since the Veitch method depends, in principle, upon t h e satisfying of the minimum absorption of a soil and the presence in the solution, which is allowed t o stand in contact with the soil over night, of sufficient calcium bicarbonate t o give an alkaline reaction t o phenolphthalein when j o cc. are boiled down t o j cc. Under t h e practical conditions of the method, however, some of t h e factors introduced may cause the results t o differ from t h e minimum absorption. The lime requirements of soils b y the HutchinsonMacLennan method,Z by t h e MacIntire method,’ by t h e Tacke method,‘ b y Siichting’s modification’ of t h e Tacke method, and by the Vacuum method of Gaithere would be much greater t h a n t h e minimum absorption and depend on t h e conditions selected, since t h e results are determined from t h e absorption when t h e soil is in equilibrium with a large excess of calcium bicarbonate in solution. The minimum absorption of a soil may be determined as defined above by subjecting t o prolonged contact a constant weight of soil with decreasing concentrations of bicarbonate solution or increasing weights of soil with a constant concentration of bicarbonate solution and determining the point where complete absorption occurs. For t h e routine examination of soils, where great accuracy is not required, a rapid approximate method of determining lime requirements has been worked out and appears t o give good results. It was found t h a t when “acid ” Hawaiian soils were shaken with solutions of sufficient concentration t o insure a fairly rapid contact of solute with soil particles, an extemely rapid absorption reaction takes place, approaching in velocity t h a t of an ionic reaction with a soluble acid, which reaction is followed by a much slower increase in t h e absorption with the time. This is illustrated by the following experiment: zoo cc. portions of 0.01 N calcium bicarbonate solution were measured out in 500 cc. Erlenmeyer flasks. The soils used were three typical acid Hawaiian soils and an alkaline station soil containing 1.63 per cent CaO. I O g. of soils were added t o each flask and the flasks immediately stopped and shaken vigorously by hand for I , 2 , 3, 4, j, 7 and Io-minute periods. At t h e conclusion of the period of shaking, t h e flasks were opened, and the contents filtered through a 24 cm. folded filter paper, discarding the first 40 or 50 cc. of filtrate. 100 cc. of the filtrate were titrated with 0.1 N HCI, iising methyl orange as an indicator. The absorption was measured by the difference in titration between 1
Jour. Amer. Chem. SOC.,24 (1902). 1120-1128; 26 (1904). 637-662.
a LOC.cit. a Ibid. 6
Chem.-Ztg.. 2 1 (1897). 174175. Z . angev. Chem., 2 1 (1908), 151-153.
0
THISJOURNAL,
4
8 (1916), 243-246.
T E E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
39
I O O cc. of t h e original bicarbonate solution and of t h e filtrate, 0.1cc. of 0.1N acid difference in titration being equivalent t o a n absorption of 0.01 per cent calcium carbonate by the I O g. of soil. The results are given in Table I and in graphical form in Fig. I .
TABLEI-ABSORPTION FROM CALCIUMBICARBONATE SOLUTIONS BY HAWAIIAN SOILSUNDER VARIOUSPERIODSOF CONTACT Absorption expressed as calcium carbonate in per cent of the weight of the soil Haiku Kaiwiki Waipio Alkaline Time of shaking Ninutes Soil Soil Soil Station Soil 1. . . . . . . . . . . . . . .0.17 2 . . . . . . . . . . . . . . . 0.20 3 . . . . . . . . . . . . . . .0.23 4 0.25 5 . . . . . . . . . . . . . . . 0.26 7 0.28 IO 0.30
...............
...............
...............
0.34 0.39 0.41 0.43 0.45 0.48 0.50
0.24 0.29 0.35 0.36 0.37 0.39 0.41
0.03 0.04 0.05 0.05 0.05 0.06 0.06
An examination of Table I and Fig. I shows, with t h e Haiku and Kaiwiki soils, t h e very rapid reaction taking place during the first minute of shaking a n d t h e much slower absorption which follows. With t h e Waipio soil, the rapid reaction apparently requires 3 minutes' shaking for completion. The alkaline station soil shows a slight, slowly increasing absorption. It should be noted t h a t t h e absorption during the first rapid
ALKALINE STATION 59,L u o
-3
I
I FIG. I-CURVES THE
2
3 4 5 7 TIME OF SHAKING
8
3
IOfilN.
SHOWING THE EFFECTOF THE TIME OF SHAKING UPON ABSORPTION B Y HAWAIIAN SOILSFROM CALCIUM BICARBONATE SOLUTION
reaction corresponds closely with the lime requirements b y t h e Veitch methodl which are 0.17, 0.34, and 0.32 per cent calcium carbonate for t h e Haiku, Kaiwiki and Waipio soils, respectively. The method of examination used in t h e above experiment has been applied t o over 80 Hawaiian soils, and t h e absorption during t h e first rapid reaction appears t o offer quite an accurate measure of t h e lime requirements of these soils. Determining t h e lime re-
' L O G . cit.
Vol.
IO,
No.
3
quirements of a soil by t h e absorption during a single shaking of one minute appears sufficiently accurase for routine soil examinations. Due t o the known peculiar nature of Hawaiian soils, 48 soil samples were secured for camparison from 8 different mainland states a n d the method used in the above experiment applied t o these samples. It was found t h a t the time of shaking could be shortened t o I O seconds for these mainland soils. The absorption during this I O seconds' shaking corresponded closely with t h e lime requirements for these soils by t h e Veitch method and with t h e amounts of lime which general experience has found best in field trials, running from I. to 3 tons of calcium carbonate per z,ooo,ooo lbs. of soil for ordinary acid soils and about 6 t o 8 tons for acid peats. The method appeared t o distinguish easily alkaline from acid soils as' t h e alkaline soils had b u t a small absorption (less t h a n 0.06 per cent calcium carbonate). For mainland soils, the following procedure is therefore recommended as a rapid, approximate method of determining lime requirements: Measure out zoo cc. of 0.01 N calcium bicarbonate solution into a 500 cc. Erlenmeyer flask. Add I O g. of the soil t o be examined t o the flask, stopper and shake vigorously by hand for I O seconds. Filter through a large folded filter paper, discarding t h e first 40 or jo cc. of filtrate. Titrate I O O cc. of filtrate with 0.1 N acid, using methyl orange as an indicator. The 0.1 difference in titration between I O O cc. of the filtrate and of the original solution is equivalent t o 0.01 per cent calcium carbonate required. Multiplying by I O the percentage calcium carbonate required gives directly the tons of calcium carbonate per 2,000,ooo lbs. of soil, which is t h e weight of soil per acre commonly assumed as being in reaction with applied forms of lime. As filtration is very rapid, it appears t h a t the absorption by this method is sufficient t o induce flocculation. A clear filtrate, easily titrated, is always secured, even with peat soils. For preparing calcium bicarbonate solutions, MacIntirel gives in detail a method of preparation by passing carbon dioxide through a suspension of calcium carbonate. The method of preparation made use of by Hutchinson and MacLennanl is more convenient. A refillable soda water syphon is used, which is charged by means of small bulbs of compressed carbon dioxide. I n this laboratory, about I O g. of C. P. calcium carbonate are placed in t h e carbonic syphon which is filled t o t h e mark with distilled water and charged. Solution is sufficiently complete in about 15 min. if t h e syphon is gently shaken. The syphon is then opened and t h e contents poured into a 2.;-liter bottle and diluted t o about 1500 cc. After t h e solid calcium carbonate has settled, t h e liquid is decanted, in portions, into a 600-cc. beaker, from which, after settling, it is decanted into a large filter paper. A glass stirring rod placed in t h e funnel along t h e sloping side underneath t h e filter paper aids t h e rapidity of filtration. Decanting and filtering in this manner makes t h e filtration a very rapid process. T h e filtrate is shaken t o insure uniformity and t
Loc. Cit.
Jan., 1918
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
5 0 cc. are titrated with
0.1 N
acid, using methyl orange. The filtrate is then diluted t o t h e desired concentration, which can be done with sufficient accuracy b y measuring the filtrate and the diluting water into a 4-liter bottle with a 500-cc. graduated cylinder. The accuracy of the dilution is confirmed b y titrating I O O cc. of t h e diluted solution. A 0.01 N solution is used as this concentration is fairly stable provided the containing bottles are kept stoppered. It was not found necessary t o displace t h e air in t h e flasks with carbon dioxide during determinations when this concentration was used. The calcium carbonate which settled when t h e liquid was decanted is returned t o the syphon which is rechai-ged and set aside until a fresh solution of bicarbonate is required. While the 0.01 N solution is fairly stable and may be kept under pressure, it is better, however, t o prepare t h e bicarbonate solution fresh each day. Any solution remaining unused from the previous day may be added to the fresh solution before filtration. HAWAIIAGRICULTURAL EXPERIMENT STATION HONOLULU, T. H.
REVERTED PHOSPHATE B y CARLTONC. JAMES
TABLEI-PER
CENT WATER-SOLUBLE
PHOSPHORIC
ALLOWEDTO
B-LIME
3 I
8
11 14 16 20 24 29 35 48
;:is .... ....
6.08 5.37
....
8.6
.... .... 5.67 ....
6.72
4.6
.... 5.08 .... 4.47 ....
7.5 6.63
....
5.39
....
4.72
....
....
3.98
3.82
....
2.44
.... ....
2.23
4.8 4.59 4.47
4.3 3.8 3.54
3.55
2.97
....
7.6 7.0
ACID
IN
MIXTURES
STAND
A-ACID PHOSPHATE & GUANO Period of --MIXTURE-Standing No. 1 No. 2 No. 3 No. 4 On mixing 9 . 1 2 days
33
....
....
SUPERPHOSPHATI3 & L I M E
MIXTURE CONTAINING Period of 15% 30% Standing Lime Lime On mixing 1 5 . 8 1 13.02 6.93 2days 10.17 6.23 6 9.05 8.34 5.52 l14 o 7.87 5.05 4.70 18 7.23 21 7,23 3.82 25 6.99 3.98 4.58 28 6.76 35 6.64 4.19 4.11 40 6.46 5.67 54 6.51 5.62 68 6.46 45 8 0.93 4.60 2.90 1580 0.48
were prepared, t h e constants of which were acid phosphate and brown guano, the name given t o a low-grade Laysan Island phosphate containing coral sand. The variable was lime, CaO. Each sample contained 2 0 0 g. acid phosphate and 2 0 0 g. brown guano: in addition, No. I contained 7.4 g. of lime, the theoretical amount t o revert all water-soluble lime phosphate, disregarding whatever effect t h e calcium carbonate in t h e brown guano might have. No. 2 containqd twice as much lime, 14.8 g. To Nos. 3 and 4 were added 2 g. and 4 g. of lime, respectively. The samples
Received August 28, 1917
As there has been so much published recently concerning t h e reversion of acid phosphate, its value after reversion, and its effect upon plant growth, i t seems advisable t o set forth some of t h e work done b y t h e writer along these lines during t h e last eight years. This work was inaugurated and continued in order t o control better t h e complete fertilizer mixtures, a n d to provide a more effective phosphate for soil conditions in Hawaii. Moreover, t h e contradictory results and opinions of investigators and control chemists elsewhere has made i t necessary t o verify or disprove them when applied t o conditions in Hawaii. It has been generally held t h a t iron and aluminum phosphates are of little value as a source of phosphorus. Now comes a recent publication b y McGeorgel showing t h a t in sand cultures with millet, ferric and aluminum phosphate produced more vigorous plants t h a n acid phosphate, sodium phosphate, phosphate rock or Thomas slag. Similarly, it has been held t h a t reverted phosphate is of less value t h a n acid phosphate. Considering t h e results obtained here b y a n acid phosphate which has been reverted, we are inclined t o believe t h a t under certain conditions prevailing in Hawaii, reverted phosphate gives t h e better results. E XP E R I Y E N T A L
I n a previous article2 the writer showed t h a t some reversion may be expected from the action of lime, carbonate of lime, and a mixture of carbonate and phosphate of lime in mixed fertilizers. I n this article methods, means and materials used t o revert t h e acid phosphate completely, are considered. I n the first experiment four laboratory samples 1 2
Hawaii Agric. Exp. Station, Bull. 41. THISJOURNAL, 9 (1917), 682.
became appreciably warm, and one hour after mixing, the temperatures in Nos. I and z were 3 5 a n d 36' C., respectively, a rise of g and 10' C. over room temperature. At intervals, analyses were made b y the uranium volumetric method for water-soluble phosphoric acid, the results of which are shown in Table I A . This table shows a reversion of from 5.16 t o 5.63 per cent of water-soluble phosphoric acid, and also t h a t the greater reversion is caused b y the greater amount of lime. These points have been laid out diagrammatically on quadrille paper and a smooth line drawn through the points plotted t o show the rapidity with which the action takes place a t first and how i t is gradually retarded. It will be seen t h a t if the lines were extended, considerable time would elapse before all the phosphoric acid would become reverted. While these results were satisfactory, it was deemed advisable t o remove the brown guano as the supply was becoming limited, and t o t r y larger samples over a longer period of time. Some time later, with this in mind, another laboratory experiment was carried on with lime superphosphate, t h e analyses being made a t close intervals
