LI-0-Y -4-l-D B I Z Z E L L O N
V - A I L A B I L I T Y OF SOIL XITR0GE.V.
The results where 2 grams of material were used show insufficient differences in availability to make results conclusive. The range was from 6 j . 4 to 9 0 . 0 , with an a\-erage of So. 3. IVhere ij mg. of organic nitrogen were used striking differences were obtained, but, owing to the large amounts of material used, the permanganate was in excess (as shown by the colored filtrate) in only 4 out of 2 1 cases, thereby introducing a possible inaccuracy in the results. The range was from 5 4 , 3 to 84.j , with an average of So. j . Where .+j mg. of organic nitrogen were used the results are \-cry satisfactory, only 2 of the 2 1 samples not showing the permanganate color in the filtrate. The range was from 6 2 . 4 to 93.3, with an arerage of 7 8 ,I . Fortunately we know something of the history of certain of the samples which aids us materially in judging the value of the method. I n e\-er?- case where the presence of peat was suspected from the color of the citrate filtrate, the manufacturer was ad\-ised of our finding. In some cases the use of peat was frankly admitted, together with the amount used per box, in others the use of' peat denied and a satisfactory esplanation made. For instance, in S o s . 9 and I O the manufacturer denied the use of peat but admitted the use of 150 lbs. of dirt per box; our a\-ailabilit?- figures of 9 3 . 3 and 8 8 . 9 , respectively, confirm the correctness of his statement and show that the color of the citrate filtrate, unsupported by other evidence. is not conclusiA-e as to the presence of peat. In S o . I j the manufacturer admits using 246-2.6 j per cent. nitrogen; the al-ailability figure is j 6 . 4 . In S o . 1 5 the manufacturer admitted that he had used 312 lbs. of peat ( 2 . j per cent. nitrogen) per ton in one of the samples making up our composite, while in the other no peat, but high-grade blood, was used. The separate samples. S o s . I j t z and I j b , in the table, n-ere tested, and in one an a\-ailability of 7 0 . 9 n-as obtained and in the other S g . 7 , thus confirming the manufacturer's statement and proving the value of the method. In S o . 2 5 , from the same manufacturer. a similar statement n-as made, 2 j ( z containing 2 0 0 lbs. peat ( 2 . 5 per cent. nitrogen) and 2511 no peat (the form of nitrogenous material used was not stated). in the In the peat portion the availability was j 4 other 70 9 : apparently in the latter some other relatil-ely inert form of nitrogen was used, assuming the manufacturer's statement t o be correct. By this method, setting the minimum availability a t So. 13 of these samples would be condemned and 6 passed, the last without exception being fertilizers in which the total nitrogen is high, and the watersoluble nitrogen also relatively hiuh. Three of these 9 we know to contain no peat. Twenty samples of tankage and three oi garbage
313
tankage were also tested by this method. The availability of 18 samples of tankage ranged from 8 7 . 9 to 9 4 . 0 , with a n average of 9 2 . 5 ; the other 2 tankages showed availabilities of S I 6 and 8 3 . 7 , which, together with their low percentage of phosphoric acid, suggested the presence of peat. The three garbage tankages showed availabilities of 47 5 , 48 o and51 I. -
AVAILABILITY O F SOIL NITROGEN I N RELATION TO THE BASICITY O F THE SOIL AND TO THE GROWTH O F LEGUMES. B y T LYTTLETON LYON AND
J\\lES
A
BIZZELL.
Received April 2 1 1910
I t is well known that the lack of lime compounds in the soil is a serious hindrance to the growth of alfalfa. The application of lime to the soil not only produces a larger growth but also a better color of the alfalfa plants. These differences may frequently be noticed to extend to the grass or to the weeds growing with the alfalfa. The beneficial effects of the lime are apparently shared by the yegetation associated with the legume. The yucstion as to the nature of the processes by which this improvement takes place naturally presents itself. The phenomena observed on our experiment plats were these: (I) The alfalfa grew better and had a better color on the limed soil. (2) The grass and weeds growing with the alfalfa were likewise better on the limed soil. (3) On two plats of land both of which were limed, but one of which was planted to timothy and the other to a mixture of alfalfa and timothy, the timothy made a better growth on the plat having the mixture. Analyses were made' of alfalfa from ten plats of land. One-half of each plat had been limed four years before a t the rate of 3,000 pounds of quicklime per acre. The indicated lime requirement of the top foot of soil as determined by Yeitch's method was 4,000 pounds per acre. In every case the alfalfa from the limed portion of the plats contained a higher per cent of nitrogen. -411 samples of alfalfa were taken a t the same time, and represented as closely as possible the same stage of growth. Examination of the alfalfa roots showed the presence of tubercles in practically all cases. The difference in composi-' tion was, therefore, not due to the presence or abience of tubercles, which has been shown by Smith and Robinson1 to influence the nitrogen content of alfalfa. On these plats Erzgeron awLy1Us was a common weed, and this apparently shared the good or poor condition of the alfalfa. Samples of the weed were taken from the limed and unlimed portions of each plat. Sine of the ten plats produced plants with a higher nitrogen content on the limed soil. \Iichigdn Stdtiriii Bicll 224, pp 125-132.
T H E J O U R N A L OF I N D U S T R I A L A N D ELVGIi\iEERIA-G CHE3IISTRI'.
314
The following table shows the close relation between the basicity of the soil, the yield of alfalfa, and t h e nitrogen content of the alfalfa and of the weed Erigcron annus growing with i t : TABLEI.-EFFECT
O F L I M I N G S O I L O N T H E COMPOSITION
Euioeron annus GROWING WITH IT AND
OF
ALFALFA,
ALSO
O N T H E N I T R A T E S I N T I I E SOIL.
Per cent. Per cent. nitrogen Yield Per cent. nitrogen in of h a y alfalfa in pure Erigeroit Nitrates first in alfalfa QWLUZ in dry cutting. mixed (water- (watersoil Lbs. hay. free). free). p.p.m.
Plat KO. Treatment. Limed 741 . Unhmed . . . . . . .
{
.........
...... .........
Unlimed. 745
746
!Limed (Unlimed ....... Limed , Unlim ,
{
Unlimed.. . . . . .
103 49
50 30
2.65 2.23
1.17 1.52
2.6 3.8
131 110
80 75
3.36 2.74
1.67 1.26
9.7 5,6
138 96
70 65
3.53 3.04
1.76 1.43
7.1 4.3
107
60
3.13 2.52
1.74 1.38
7.8 5.4
130 86
80 70
3.55 2.57
1.96 1 .46
20.4 2.9
112 96
80 80
3.46 2.99
1.94 1.34
3.3 1.7
3.39 2.24
1.63 1.38
3.6 2.9
3.21 2.38
1.79 1.41
8.0 7.7
79
T5
69
70
3.54 2.35
1.74 1.42
9.8 5 I
35 15
60 20
3.19 2.35
1.68 1.47
8.5 3.3
It is very apparent from these figures that the nitrogen content of alfalfa is increased by the addition of lime to the soil. I n the case of the accompanying non-leguminous vegetation there still remained a question as to whether the higher percentage of nitrogen is due to the effect of lime or to some influence either direct or indirect that could be traced to the better stand and growth of alfalfa on the limed soil. To throw some light on this question, samples of timothy hay were analyzed. Samples I and I1 were grown on land that was limed. Sample I was grown on a plat of alfalfa and timothy mixed. Sample I1 had no alfalfa sown with it. Both analyzed samples were pure timothy. Simi'ar determinations were made of timothy grown on unlimed land of which Sample I11 was grown with alfalfa and Sample IV without alfalfa: . TABLEII,-XITROGEX CONTENTOF TIMOTHY GROWNWITH ALFALFA.
Soil treatment. Limed Limed No lime No lime
Sample I . Sample 11. Sample 111. Sample 11;.
Crop treatment. Grown with alfalfa
Grown without alfalfa Grown with alfalfa Grown xvithout alfalfa
A N D WITHOUT
Per cent. nitrogen in timothy nater-free. 2 .49 2.01 1.55 I .44
Samples I and I1 cannot be compared with samples I11 and IV as I and I1 were taken June 1st. and I11 and I V on June 19th, the percentage of nitrogen naturally being greater in the younger grass. It may be concluded from these results that the growth of alfalfa
July, 1910
influences the nitrogen content of the timothy growing with it, whether growing on limed or unlimed soil. It does not, however, permit of any conclusion as to the effect of lime alone on the composition of the timothy. Table I contains a statement of the nitrates present in the soil a t the time the alfalfa was harvested. It will be noticed that on every plat except Plat 741 the nitrates were higher on the limed than on the unlimed soil, in spite of the fact that the yields of hay were much greater on the limed soils. As the crop was a legume, it cannot be positively stated that the draft of the crop upon the nitrates in the soil was greater on the limed soil. It, nevertheless, raises the question whether nitrification is favored by the addition of lime to the soil when the soil is in need of lime. In other words, whether an increase in the basicity of the soil makes it more favorable for nitrification. -%notherquestion raised is whether the more luxuriant growth of the alfalfa on the limed soil produced a condition more favorable to nitrification. As a means of gaining information on this subject, nitrification tests were made in soils from a series of plats, of which four had been limed a t the rate of 2,000 pounds per acre four years before, and four had never received any lime. Two of these plats were planted to alfalfa, both on the limed and unlimed portions, one to a mixture of alfalfa and timothy limed and unlimed, and one to timothy alone limed and unlimed. The nitrification tests were made according to the following method: IOO grams of the moist soil were placed in a 2 5 0 cc. bottle. To this was added 500 milligrams of ammonium sulfate and sufficient water to bring the soil to a moisture content of z j per cent. calculated on the basis of dry soil. The bottle, after insertion of a tight cotton plug in the mouth, was placed in the incubator and kept a t a temperature of 30' C. for ten days in the case of one test and twenty days in the other. TABLE111
--SITRIFICATION
'PESTS
WITH ASD
Plat hTo. Treatment. Limed 4001a Limed 4002a 4003a Limed Limed 4004a
LIMED ALFALFA.
I S SOILS
WITHOUT
Crop.
Not limed Xat limed h-ot limed Not limed
5.5 Alfalfa Timothy 7.4 -4lfalfa and timothy 5 . 0 10.5 Alfalfa
-
Alfalfa Timothy Alfalfa and timothy Alfalfa
.
