Mar., t916
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 Conductivity Value
Maximum. .
-
Difference. , . , , , , , , , . , , , , ,
...............
.
. ..
Range, per cent of mean.. . . . . . . . Range, per cent of minimum.. , . . .
134 60 75
Canadian Volumetric Lead No. Lead No. 7.55 6.6 1.72 4.8
-
__
5.83 3.22 181 339
1.8 5.77 31 37.5
PITON-MAPLE sYRUPs-We have applied t h e method t o 5 of t h e non-maple a n d compound maple syrups referred t o in Paper I, v i z . , Xos. 7 and 13 of Table VIII-a golden syrup and a syrup made from a pale brown commercial sugar-the latter of which h a d given a conductivity value within t h e limits for maple syrup-and Nos. 11, 31 a n d 33 of Table I X . All five of these syrups gave smooth curve plots. A compound syrup, a syrup sold as pure b u t known t o be adulterated, a n d 5 syrups made from raw cane sugars by dissolving in water, boiling t o 219' F., a n d filtering, gave smooth curves. Two other syrups made from raw cane sugars a n d a sample of raw beet sugar gave breaks a t 3 . 4 , 4 . I and 4 . 2 , respectively,--. all outside t h e limits for maple syrups. Two of these syrups had conductivity values (143 a n d 210) within the limits found in maple syrups. In 3 samples of cane molasses no material change in t h e electrical resistance (which, of course, was much lower t h a n with maple syrup) was produced by t h e addition of t h e I O cc. of lead subacetate solution. T I M E R E Q U I R E D F O R T H E TEST-The time required t o reboil, filter and cool t h e syrup and t o make t h e test is about half a n hour. T h e time consumed in t h e test itself is less t h a n 5 minutes MEASUREMENTS
243
bining as i t does t h e merits of rapidity, narrow range of values in genuine maple syrup a n d rapid falling off or early disappearance as t h e syrup is adulterated with cane sugar syrup, this test will prove t h e most useful single test for purity of maple products yet proposed. MACDONALD COLLEGE, PROVINCE OF QUEBEC
ON
SUM M A R Y
I-The volumetric lead subacetate test consists in diluting the syrup t o I O times its original volume and titrating with lead subacetate solution of sp. gr. I . 033, obtaining t h e end-point b y measurements of electrical resistance. 11-The volumetric lead number is t h e abscissa of t h e point of intersection of two straight lines on t h e plot of volumes as abscissae with resistances as ordinates. 111-Seventy genuine Quebec 1914 and 191j syrups gave volumetric lead numbers ranging from 4 . 8 t o 6.6-a range of 3 7 . 5 per cent of the minimum, as compared with 97 per cent for t h e conductivity value. I n 2 8 of these syrups, t h e ranges of volumetric lead number, conductivity value and Canadian lead number were, respectively, 37. j, 7j and 339 per cent of t h e minima. IV-Seventeen out of 2 0 syrups containing 30 per cent of sucrose syrup gave smoot,h curve plots: 18 out of 20 containing 40 per cent sucrose syrup gave smooth .curves and t h e remaining two gave intersections outside t h e limits for genuine syrups. V-Of 18 adulterated a n d non-maple syrups, 1 2 gave smooth curve plots, 3 gave intersections outside t h e limits found in genuine syrups a n d in t h e remaining 3 (cane molasses) t h e electrical resistance remained constant. c 0 pic L u SI 0 N If future work by ourselves and others corroborates our experience of its reliability, we believe t h a t , com-
COMPARISON OF LIME REQUIREMENT METHODS By J. W. AMES AND C. J. SCHOLLENBERCER Received September 17, 1915
T h e results presented have been obtained in t h e soil investigations pertaining t o t h e effects of lime treatment being conducted at t h e Ohio Experiment Station. An estimation of t h e lime requirement in relation t o effectiveness of applications of lime under different conditions of fertilizer treatment has been made, using several of t h e methods proposed for.this determination. METHODS-The methods used included t h e Veitch, Hopkins, Hutchinson-MacLennan,' RlacIntire2 a n d Vacuum3 methods. The Veitch a n d t h e Hopkins, which are two of t h e more generally used methods, are entirely different in principle. The HutchinsonMacLennan method and t h a t proposed by MacIntire, two of t h e more recent of t h e numerous methods which have been published, are somewhat similar, a solution of calcium bicarbonate being t h e carrier of base in t h e two latter-mentioned methods. I n the Hutchinson method t h e soil is kept in contact with t h e bicarbonate solution for 3 hours and a portion of t h e filtrate is titrated against N / I O acid, using methyl orange as indicator, t o obtain a figure for t h e amount of calcium absorbed. The MacIntire method differs in t h a t the bicarbonate solution is evaporated in contact with t h e soil t o a thin paste; after transferring t o a suitable flask, t h e excess of calcium carbonate is determined b y addition of acid a n d estimation of liberated carbon dioxide. son-These five methods were compared on soils from a number of variously treated plots from one of t h e fertility sections of t h e Wooster farm, located on silt loam soil which is largely derived from sandstones a n d shales. So far as its history is known, it contains no natural supply of calcium carbonate, and each year it becomes increasingly difficult t o secure a satisfactory growth of clover unless lime is applied. The west half of t h e plots had been treated with ,1875 lbs. per acre of calcium oxide in 1903, and 2 0 0 0 lbs. of limestone in 1909. The composition of t h e lime materials applied was such t h a t the equivalent of 5 7 0 0 lbs. of calcium carbonate had been applied t o the limed halves of t h e plots previous t o t h e time samples were taken from the plots, which was 3 years after t h e last treatment with lime. From determinations of calcium carbonate which Chem. News, 110, No. 2854, Bug. 7, 1914. Am. Fert., 41, No. 1 1 . Nov. 28, 1914. 8 This method was proposed by E. W. Caither, formerly of this laboratory, and is essentially a modification of the Tacke procedure for estimation of degree of acidity of peat soils. Instead of boiling the mixture of soil and calcium carbonate a t looo, the soil was heated in contact with finely divided calcium carbonate under reduced pressure as in the Marr (Jour. Agr. Science, 3, Part 2 , p. 155) procedure for determination of soil carbonates; the carbon dioxide liberated by decomposition of the calcium carbonate by the soil is taken as a measure of the lime requirement. 1
a
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
244
are available for several of t h e differently fertilized plots on which lime requirement determinations were made, it is evident t h a t t h e greater portion of the lime applied has disappeared or no longer exists in t h e carbonate form. QUANTITIES O F CALCIUM CARBONATE PRESENTI N THE LIMEDHALVES Plot FERTILIZER Lhs. per acre 0 None . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
. . . . . . . . . . . . . . . . . . 225 ................................ 450
Sodium nitrate.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575 11 Complete.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 24 Complete, including amm carrier of nitrogen None 26 Complete, inciuding bone meal as carrier of phosphorus.. , . 250 29 Complete, including basic slag as carrier of phosphorus, . , . . 300 5
When tested with litmus paper, all of t h e soilst h e limed soils containing a small amount of lime carbonate residual from application made, as well as the unlimed soils--gave a decided acid reaction. The amounts of C a C 0 3 required for 2,000,000 lbs. (approximately) per acre 6 in. of soil are stated in Table I. TABLEI-LSS,
Plot 0
2 3 5
11 24 26 29
FOR
2,000,000 I,Bs. SOIL
FERTIL IzER
one .................................
3440 2000 3550 Alk. 2250 2000 3850 Alk. 2400 2000 3550 Alk. 2650 1200 3550 Alk. 2500 1800 3850
None f Lime ......................... 100 Acid PhosDhate.. ...................... 2640 Acid PhosDhate Lime.. . . . . . . . . . . . . . . 80 Muriate Pbtash. ........................ 3240 Muriate Potash Lime.. . . . . . . . . . . . . . . 200 Sodium Nitrate.. ...................... 3640 Sodium Nitrate L i m e . , . . . . . . . . . . . . . . 120 Acid Phos. f Mur. Pot. Sod. Nitr.. . . . 3080 Acid Phos. Mur. Pot. Sod. Nitr, Lime ............................... 80 Acid Phos. Mur. Pot. Amm. Sulf. 4240 Acid Phos. Mur. Pot. Amm. Sulf. Lime ............................... 260 Bone Meal Mur. Pot. Sod. Nitr. 2940 Bone Meal Mur. Pot. f Sod. Nitr. Lime ............................... 360 Basic Slag 4- Mur. Pot. iSod. Nitr. 2560 Basic Slar Mur. Pot. Sod. Nitr. Lime ............................... I50 Manure ............................... 2760 Manure Lime.. . . . . . . . . . . . . . . . . . . . . 120 I
18
CaCOa IXDICATED
+
+ ++ ++ + .
+ + +
++ ++ + +
+ +
+ -+
2925 7300 1700 4900 2700 7800 97.5 3800 3025 1600 2550 6200 1250 4225 2825 7100
....
Alk. 2500 1375 5900 3000 4000 2700 8300
200 2850 1475 5700 2000 3700 2250 7350 Alk. 2900 1325 4050 1200 3600 2250 6600
Alk. 2100 1075 4050 2600 4200 3100 8500
Alk. 2950 1950 5200
The fact t h a t no residual carbonate is present in the soil, a n d the poor growth of clover on the plot which received ammonium sulfate as the nitrogen carrier, is in accord with t h e lime requirement indicated by t h e Veitch and Hopkins methods, since t h e figures for t h e unlimed end of this plot are higher t h a n those obtained for a n y of t h e other plots, by either of these methods, while t h e MacIntire, Hutchinson and I'acuum methods each show t h e highest lime requirement in t h e case of t h e manure-treated plot. X comparison of t h e figures for t h e soils where three different carriers of phosphorus (acid phosphate, bone meal a n d basic slag) have been used, shows a higher lime requirement for t h e acid phosphate-treated soil by the Hopkins, MacIntire a n d Hutchinson methods. The Veitch and Vacuum methods give slightly higher results for t h e bone meal plot, while the Hutchinson method gives t h e same figure for both t h e bone meal and basic slag plots. K i t h this one exception, all the methods indicate a lower requirement for t h e basic'slag plot. The figures by those methods which show a lower requirement for the basic slag and bone plots agree with t h e growth of clover on t h e unlimed ends of these plots, since a more satisfactory stand of clover is secured on these plots t h a n on t h e plot where acid phosphate is t h e carrier of phosphorus. The variations shown by several of t h e methods
Vol. 8, NO. 3
indicate the possible usefulness of some of these methods for comparative purposes where different soil treatments have been made. For t h e soils which have been limed. but with amounts which were evidently too small, since the growth of clover on t h e limed halves of the plots indicates t h a t they will be benefited by additional quantities, the AIacIntire, Hutchinson and Vacuum methods have, no doubt, given a better indication of t h e optimum quantity of lime necessary t o make conditions satisfactory for t h e growth of leguminous plants. If either the Hopkins or t h e Veitch test were used t o obtain a figure for t h e limed soil's requirement, t h e results would lead to erroneous conclusions, because t h e Yeitch method indicates t h a t the limed halves of all t h e plots are alkaline, excepting t h e one where ammonium sulfate has been used; and t h e Hopkins test has shown a very small requirement for t h e limed halves of t h e plots, t h e largest amount of calcium carbonate required, according t o this test, being 360 lbs. per acre. The results obtained by t h e Hutchinson, MacIntire and Vacuum methods are much higher t h a n those by either t h e Hopkins or Veitch test for t h e soil which has been limed. While t h e figures obtained for t h e unlimed soil by t h e several methods do not exhibit t h e wide variation t h a t is found for t h e limed soil by the Veitch and Hopkins methods as compared with t h e other methods, there are appreciable differences indicated. Excepting the ammonium sulfate-treated plot, the results for the unlimed soil are uniformly lower by the Veitch test. I n some instances there is a very close agreement between t h e Hopkins and MacIntire results, although in t h e majority of cases t h e Hopkins a n d Hutchinson methods agree more closely. The results b y t h e Veitch method for Plots 24 and 26, which have received different carriers of phosphorus a n d nitrogen, correspond t o those secured by t h e Hutchinson method. I n the case of the manure-treated s d , the results by the Veitch and Hopkins methods are practically t h e same. The Vacuum method shows a much larger amount of lime required t h a n is indicated by t h e other methods, and it may be t h a t for non-calcareous soils t h e figures closely approximate t h e actual amount of calcium carbonate required. However, for many soils naturally supplied with calcium carbonate and which gave an alkaline reaction with litmus, results by this method indicate a further need of lime, t h e amount required in many cases being considerably in excess of t h e amount of calcium carbonate present. This would seem t o indicate t h a t t h e results obtained for lime requirement are probably too high and t h a t the method mould not be applicable t o soils in general. I n Table I1 t h e differences between t h e results obtained for t h e limed and unlimed soil of the several fertilized plots is expressed in percentages of t h e figures for t h e unlimed soil. Considering t o what extent t h e soils lime requirement has been satisfied following t h e lime treatment, the results obtained by the Hopkins and Yeitch methods exhibit a marked uniformity, although the lime requirement for t h e un-
T H E JOURNAL OF INDUSTRIiiL A N D ENGINEERING CHEMISTRY
Mar., 1916
limed soil by t h e Hopkins test is considerably in excess of t h e amount shown b y t h e Veitch test. T h e figures show t h a t t h e decrease in lime requirement as measured by either t h e Hopkins or Veitch test is quite uniform for all t h e plots. TABLE11-PERCENTAGESOF THE ORIGINALLIME REQUIREMENT SATISFIED BY LIME TREATMENT
Many changes have taken place in t h e soil during 16 years. Following t h e deeper plowing and better cultivation the soil has received since t h e 1896 sampling, t h e physical condition of t h e soil and its organic content will have been affected t o a n extent sufficient t o cause t h e variations observed in t h e lime requirement of t h e old and new soil by t h e several methods. INFLUEKCE
SOIL TREATMENT
97 N o n e . . . ..................................... 97 AcidDhosohate.. ............................. . . . . . . 94 Muriate of Potash.. ..................... . . . . . . 96 Sodium Nitrate.. ....................... Acid Phos. Mur. Pot. Sod. Nitr.. . . . . . . . . . . 97 Acid Phos. Mur. Pot. f Amm. Sulf.. . . . . . . . . . 94 Bone Meal Mur. Pot. Sod. Nitr.. . . . . . . . . . . 87 Sod. Nitr.. . . . . . . . . . . 94 Basic Slan &fur. Pot. Manure ......................... . . . . . 95
-~
+++ +
+ ++
100 100 100 100 100
93 100 100
100
36 37 25 29 35 28 21 41 29
41
60 47 50 51 45
32 51
ii
17 31 41 45 52 38 37 39
The MacIntire and Hutchinson methods exhibit a variation between t h e soils variously fertilized, t h e figures b y t h e MacIntire procedure for t h e majority of t h e soils showing t h a t a smaller percentage of t h e lime requirement has been satisfied b y t h e lime treatment previously given t h e plots. LINE R E Q U I R E M E K T DURING 16 Y E A R S A comparison of t h e lime requirement figures for soil sampled in 1896 and again in 1912 is of interest in relation t o changes which have taken place in soil during a period of 16 years. By inspection of results grouped in Table 111, it will be noted t h a t , as measured b y t h e Hopkins method, t h e requirement of t h e unlimed soil at t h e earlier period is markedly lower t h a n t h a t obtained b y t h e other methods, while t h e same soil a t t h e latter date of sampling has a higher requirement b y t h e Hopkins method t h a n by the other methods, excepting t h e Vacuum method, a n d in one case t h e MacIntire method. The Veitch results being lower at t h e latter sampling as compared with t h e earlier sampling are just t h e reverse of those b y all the other methods which have indicated a decidedly increased lime requirement for t h e soil after a period of 16 years. Although all t h e methods excepting t h e Veitch show a n increase CHANGES IN
TABLE111-COMPARISON
LIME REQUIREMENT O F SAME SOIL SAMPLED 1896 ASD 1912 HopMac- Hutch- VacFERTILIZER Sampled kins Veitch Intire inson uum AmmoniumSulfate. . . . . . . . . . . . . . . 1896 750 4000 3000 1750 5500 AmmoniumSulfate 1912 4240 3000 4000 2700 8300 Ammonium Sulfate Lime.. . . . . . 1912 260 200 2850 1475 5700 1896 625 4000 2700 1575 6100 None ........................... 1912 3440 2000 3550 2925 7300 N o n e ........................... 1912 100 Alk. 2250 1700 4900 None ........................... OF
IN
...............
+
in t h e lime requirement for t h e soil at t h e latter date as compared with t h e earlier sampling, t h e Hopkins method indicates a much greater increase t h a n t h e other methods. I n direct contrast t o t h e lower results by t h e Veitch method for t h e soil at t h e later date compared with results by the same method for t h e first sampling, is t h e fact t h a t for t h e soil ,when first sampled, t h e Veitch method gave higher indications t h a n t h e Hopkins, MacIntire or Hutchinson methods. It should be stated t h a t t h e determinations on t h e soil cpllected in 1896 and t h a t in 1912 were made by each of t h e methods used, a t t h e same time, so t h a t t h e differences found cannot be attributed t o factors introduced b y variations in t h e procedure employed.
245
OF
VARIATIONS IK
METHOD
ON
RESULTS
It may be pointed out t h a t these methods for the determination of a “Lime Requirement” are empirical in nature, and comparatively slight variations in procedure affect the results obtained markedly. Thus, t h e Veitch method is much affected b y t h e degree of clarity of t h e extract-the clearer t h e extract t h e lower t h e lime requirement, and a method of filtration removing every trace of suspended clay might possibly show a zero requirement in a great number of cases where t h e usual procedure indicates a considerable lime requirement. On t h e other hand, all soils do not settle t o t h e same extent when allowed to stand over night, and a comparatively small amount of suspended clay will prevent any appearance of a pink color on boiling, although calcium hydroxide solution in quite measurable quantity is added directly t o t h e boiling solution. For this reason, i t was thought best t o employ filtration. Ten grams of soil were weighed into a porcelain dish, wet with sufficient water t o give about 50 cc. of liquid after t h e standard lime water had been added a n d evaporated on t h e steam b a t h as rapidly as possible, stirring once or twice before t h e mass is dry. It was then washed into a I O O cc. Jena flask with I O O cc. water, shaken occasionally for I j t o 30 minutes, a n d allowed t o stand over night. The contents of t h e flask were shaken a n d poured onto a n S. & S. 18 cm. folded filter; t h e first 3 0 or 40 cc. were rejected, t h e next jo cc. collected, a few drops of phenolphthalein added, a n d immediately boiled down t o about j cc. in a Jena beaker. A distinct pink color was taken t o indicate alkalinity, but in cases where t h e color was only faint, t h e result was recorded as doubtful and t h e experiment repeated. The Hopkins method will not give t h e same indications if another salt is substituted for KN03. I n this work, I O O g. air-dry soil were shaken with zjo c c . , N KNO8 for 3 hours, using a shaking machine, then filtered immediately, 1 2 5 cc. pipetted off, boiled and titrated with N / I O NaOH, using phenolphthalein. The factor 2 . 5 was used. The method proposed by MacIntire is quite sensitive in this respect; t h e directions call for evaporation “to a thin paste,” b u t higher results are obtained TABLEIV-LIME C,. in-. - .
REQUIREMENT BY MACINTIREMETHOD. LBS.CaC08 PER 2,000,000 LBS. SOIL
100 cc. TREATMENT CaCOa 10 Evaporated to thin paste immediately.. . . . . . . . . . . . . . . . . . . 7500 10 Evaporated t o dryness immediately.. ..................... 8200 10 To thin paste immediately, t o dryness next morning.. . . . . . . 8900 10 Let stand over night, to dryness next morning., . . . . . . . . . . . 8100 20 Evaporated to thin paste immediately., , , , , , , , , , , . , , , , , , . 5750 20 Evaporated t o dryness immediately.. . . . . . . . . . . . . . . . . . . . . . 6300
if t h e evaporation is carried t o dryness. The results also vary with t h e time required for t h e evaporation, even when i t is carried t o t h e same stage (see Table IV).
2 46
T H E JOURNAL OF I N D C S T R I A L A N D ENGINEERING CHEMISTRY
It should be noted t h a t the soil used in this experiment had a rather high requirement, and t h a t if the requirement as determined when using I O g. soil t o I O O cc. of solution was t h e correct figure, 2 0 g. of t h e soil should be more t h a n sufficient t o exhaust I O O cc. of t h e Ca(HC03)2 solution. As a matter of fact, only about three-fourths of t h e total amount of C a C 0 3 was decomposed b y t h e 2 0 g. charge. T h e soils under investigation showed a requirement of about one-third t h e total calcium carbonate in I O O cc. bicarbonate solution when 2 0 g. of soil were used; t h e evaporations were carried t o dryness as rapidly as possible. and stirred several times meanwhile. The residual C 0 2 was determined b y t h e hXarr method. The Hutchinson method seems t o be affected t o some extent b y allowing t h e soil and Ca(HC03)2 solution t o remain in contact for a period longer t h a n 3 hours. Thus, a determination in which 40 g. soil was shaken with 2 0 0 cc. C a ( H C 0 3 ) * solution for 3 hours indicated a calcium absorption of 3025 lbs. per acre; I O O g. of t h e same soil shaken with 500 cc. of t h e same bicarbonate solution for 3 hours, then allowed t o stand over night, on titration showed a requirement of 3600 lbs. per acre. The soil used for this experiment was f r o m plot treated with muriate of potash, T h e bicarbonate extract of t h e soil showed b u t a faint trace of chlorine, no potassium, b u t traces of sodium a n d magnesium. The calcium in t h e bicarbonate extract b y permanganate titration was only about 0 . 4 cc. lower t h a n t h e figure obtained by direct titration with acid, both being on t h e A.'/IO basis. This shows t h a t with t h e Hutchinson method interchange of bases plays b u t a very subordinate p a r t and t h e chief factor is absorption. The method will sometimes show a lime requirement in t h e case of a soil which contains a great excess of carbonate. For this work, 2 0 g. soil t o 2 0 0 cc. solution was t h e the air in the \Vas by coz, the bottle securely stoppered, shaken for 3 hours, immediately filtered, and I O O cc. of the filtrate titrated Orange; IOo cc. Of the with "/Io HC1, using original solution was titrated in the same way. The Vacuum method, i t will be noticed, invariably shows t h e highest figures for t h e lime requirement; this is doubtless because t h e conditions of the method are such t h a t t h e decomposition of CaCO3 b y the Soil can proceed t o a maximum without hindrance. OHIO AGRICULTURAL EXPERIMENT STATION W O O S T E R , OHIO
-~
THE ACTIVITY AND AVAILABILITY OF INSOLUBLE NITROGEN IN FERTILIZERS A S SHOWN BY CHEMICAL AND VEGETATION TESTS' By F. R. PEMBERA N D BURT I,. HARTTVELL
Received July 30, 1915
since 1908 t h e Agricultural ~ ~ Station of t h e Rhode Island State College has conducted vegetation tests in pots under greenhouse conditions t o ascertain the availability of t h e water-insoluble 1 Contribution 217 of the Agricultural Experiment StationTof the Rhode Island State College.
Vol. 8, SO. 3
nitrogen of certain brands of commercial fertilizers collected in t h e state, and in various nitrogenous substances, such as Kanona tankage, rape meal, castor pomace, etc. Until t h e season of 1910,this station had employed no means, except t h e vegetation test, €or differentiating between t h e organic nitrogen of one brand of commercial fertilizer and t h a t of another. I n March, 1910,t h e directors of t h e New York, New Jersey and New England Stations adopted t h e alkaline permanganate methodl as a means of distinguishing between the more or less active forms of t h e water-insoluble organic nitrogen of mixed fertilizers. The Rhode Island Station, having already secured results b y t h e vegetation method showing a wide variation in t h e availability of t h e water-insoluble nitrogen of certain commercial fertilizers, submitted t o Mr. C. H. Jones, for activity tests b y t h e alkaline permanganate method, some of t h e same nitrogenous materials as were used in t h e vegetation tests and he, without knowing t h e vegetation results, secured a close agreement.2 I-EFFECT
e
O F SEASOh- OhT PLANT G R O W T H
I n carrying on vegetation tests a t different seasons of t h e year, i t was felt t h a t t h e season and different soil conditions might have a very important influence upon t h e relative growth of a plant or different kinds of plants. With this in view two experiments were conducted: the j y s t from November 1 1 , 1910, t o February I j , 1911, a n d t h e secoizd from February 23, 1911,t o M a y 30, 1 9 1 1 : thus 96 days elapsed between planting a n d harvesting. I n both experiments, 6-inch galvanized iron pots were used, each containing I lb. of soil and 6.5 lbs. of a medium fine, fresh-water beach sand. Oat and rye plants were grown in pots having t h e same mixture of sand a n d soil, and oats alone T ~ e r grown e in a mixture of the Same sand and a different soil: t h e treatmentof all the pots was t h e same, with the exception of t h e nitrogenous material which was added to furnish o.I g, of nitrogen per pot except where t h e amount of blood was doubled. ill1 of the pots received 3 g. of potassium sulfate and 8 g. of acid phosphate, The mixture of sand and soil \\ras changed in each pot for t h e second experiment SO t h a t t h e two were identical in every mTay, except for t h e season of year in which they were conducted. It will be seen from the weights of t h e dry tops as given in Table I t h a t t h e plants growing from February 23rd t o May 30th made a greater growth in every instance t h a n those growing f r o m Sovember 11th t o February I j t h under late fall and early winter conditions. The per cent of nitrogen in t h e dry tops of t h e first experiment was enough larger, however, t h a n t h a t in those of t h e second experiment t o make t h e total amount of nitrogen recovered in t h e tops much ~alike in the~ two experiments ~ having i t h e same ~ treat- ~ r~-~ent. 1 Report on Gtrogen, C. H. Jones, Referee, hssociation of Official ilgricultural Chemists. Proceedings of the Twenty-seventh .4nnual Convention, 1910. 2 "The Availability of Insoluble Kitrogen in Certain Commercial Fertilizers," B. I,. Hartwell and F. R. Pember, THISJOURNAL, 3 (19111,584.
~
