THE TROPIC \L AGRICULTUKIST. |Ocr. i, ig 94 . 
phorie acid soluble in a 1 per cent, solution of citric 
acid, it would ba justifiable to as-sume that it stands 
immediate need of phosphatic mauure. 
Potash seerns to be one of the constituents of soil 
most likely to be modifiei and rendered available by 
the action of winter, w-jatliaring, frost, rain, &c. 
There is good reason to suppose that the use of 
nitrate of soda, and possibly, to some extent, of 
supirphosphate, helps to bring about by its solvent 
action on a part of the main stock in the soil a 
yearly supply of available potash. 
In two sets of field experiments on Cabbages carried 
out by the author in Sussex and Essex, pott 
salts, as an addition to phosphatic manure and 
nitrate of soda, produced an abund int increase , but 
the substitution of common alt for potash talu on 
other plots answered just as well, probably owing 
to the decomposing action of the salt on the com- 
pound silicates of potash existing in the soi'. It 
appears that the economy of potash in a soil is 
more complicated than that of phosphoric acid. — 
Gardeners' Chronicle. 
VARIOUS PLANTING NOTES. 
The Relative Value of Plants fob Green 
Manuring. — With a view to determining the amount 
of nitrogen by which various leguminous plauts 
enrich the soil, some interesting and valuable ex- 
periments were made last year on the experiment 1 
fields at Hohenheim, Wurteinbeiv. The soil was a 
heavy loam, on which Rye an I winter Peas had 
been grown iu the third year previous, Rape 
manured with superphosphate and nitrate of so a 
in the second year previoi-, aud winter Barley in 
the previous year. Al ter the Barley was harvested, 
seventeen different kinds of leguminous and other 
plants were sown for green-manuring on seventeen 
plots, each containing about 50 square yards se ar- 
ated by uncultivated strips. In September following 
the crop on each plot was dug under, an 1 Sheriff 
Wheat drilled on all the plats. The yield of Wheat 
where different leguuinous plants had been used as 
green-manures (Lupines, Clovers, Field Beans, Peas, 
Vetch, an I Serradella), ranged from 15 to 22 lb., 
averaging about '20 lb. It was lowest with Serra- 
della and highest w th red Clover an 1 white and 
ye'low Lupine. Second to the latter were Field 
Peas and Beans a d scarlet Clover. The yield with 
Kohl was 16 lb., with white Mustard 15$ lb., and 
with three varieties of Buckwheat the average yield 
Was 13 lb. per plot. It was noticed that on the 
plots, especially those with Lupines, many h^ads 
of grain were backward in ripening. On examina 
tion the roots of such plants were found t > be 
covered with a white fungus. No such fungus was 
found on the roots where non-leguminous plants 
were used for greea-manure. Iu how far th s oc- 
currence was due to the green-manuring with le- 
guminous plants was not determined. In another 
series of experiments, the object was to compare 
the total amounts o' nitrogen contained in crops of 
different leguminous plants, and in the 1 aves, 
stems, and roots of the same separately. The soil 
on which this trial was made had been in grain 
for three years previous. Whether or not it was 
manured in any way for the present crop is not 
stated in the abstrct. The seed was broadcasted 
on the different plots. It was found that the large 
Field Beans gave the largest yield of nitro^eu per 
sguare yard of land ; but, considering the cost of 
seeding this crop, it is believed that, from a finan- 
cial point of view, it does not exceed, the Lupines iu 
value. The difference in the nitrogen iu the w ite 
and blue Lupines raised from native and from foreign 
seed is very marked, the foreign seed yie'.diug over 
a third more It is seen that an acre crop of large 
Field Beans is able to take from the air and so 
give to the soil more than 225 lb. of nitrogen, while the 
same crop of Lupines yields some 165 lb. To supply 
these amounts of ni rogen in the form of nitrate of 
soda, would require from a 1000 to 1,500 lb. of that 
material.— Gardener* Chronic'e, 
The Intkhnal Tempeiiatike ok Tube*.— M. W. 
Prinz has been making observations for a period 
of nineteen months, at the Royal Qlianimj < f 
Belgium, on the variation of the temperature in 
the interior of trees. These observations show that 
the sap contains large quantities of gas, which often 
escapes with a noise which recalls tbe murmur of 
effervescing wate-. This bubbling is sometimes so 
intense as to be perceived at a distance of I feet. 
The mean annual internal temperature of a tiee 
is practically the same as that of the surrounding 
air, but the monthly means differ by two to three 
degrees. In general, it takes a day for a thermal 
variation to be transmitted to the heart of a tree. 
On some days the difference be:ween the internal 
temperature of a tree and that of the air out- 
side can vary as much as 10° C. G.-nerally the 
difference is only a few degrees. When the tern 
perature of the air fails below the fre-zin< point 
and continues t) decrease, the interior tempera! uic 
of the tree descends to a point near that at which 
the sap freezes, and remains there. The Bap 
freezes at some tenths of a degree above zero. 
The maximum absolute temperature of tne interior 
of a tree may occur some time before th i absolute 
maximum of the surrounding air, owing to the 
direct action of the spring Bun and of the air upon 
the tree deprived of its foliage. During the high 
temperatures of the summer the interior temperature 
of trees maintain itself neur 15° C , with a variation 
of '20° C. at the most, even when the thermal 
variations of theTi a-e exceptional. Speaking gene- 
rally, a large tree is warmer than the air in the cold 
mouths, and a little cold r than the air in warm 
months. — Ibid, 
Vitality of Seeds.— Toe fact that seeds of 
werds, especially of ant.ua'.-. are capabl : of retai l- 
ing fieir vitality for a number of years m tbe soi', 
is a circumstance welt known t) farmers of arable 
la d. An objection often advanced against deep 
ploughing particul irly of light soils, is that it may 
'• bring up the Charlock." To wha - . length of time 
buried seeds may contiuue alive is not certainly 
known, but the fo lowing careful y-made observations 
s nt to the Timr* by Mr. S. JamcR A. Slater, F.R S., 
of Basingfield. near Basingstoke, are well worth 
recording. — "Twenty-lour yenrs ago I purchased 
this property ( Basingfield i, a large portion of which 
was at that time arab'e laud bearing good crops of 
grain, which werd however in a very weedy condition, 
the principal weeds being Chariock (JSinapis arbeiuU), 
red Poppy [Palaver Ithoa*}, aud Fumitory ( Fmaaria 
ojncinalis). It is important to note that all three t f 
these pla ti are annuals. In the autumn of that 
year (1870 1 I laid the land down to grass, permanent 
pasture, and it has remained so ever since. I make 
hay annually with the first crop of grass, and the 
second I feed off witn sheep. From time to time I 
dress the grass with artificial manure, kainit, and 
superphosphate. None of the before-named weeds are 
ever seen unless the soil is disturbed ; but directly 
the surface is broken, and soil some 6 or 8 inches 
de p i3 bro ight up and exposed to atmospheric 
influences and ligh', all three of the weeds named 
appear in abundance, especially the Charlock and 
Poppy. This occurred conspicuously last year, 1893. 
The seeds producing these plants had been buried 
twenty-thr e years, but at depth beyond vivifying in- 
fluences, though still retaining vitality. There can be 
no fallacy in the observation ; it has occurred over and 
ove; again. Eight years ago, a ter a very hard frost 
and a tbaw, the surface of the ground being very 
rotten, I hid ■ ccision to take a wagon heavily laden 
across this pasture ; the wheels sank deeply into the 
soil, and tore up the ground, bringing to tbe surface 
much sub-soil. In the spring these furrows were 
filled with Charlocks, and presently, when they 
flowered there were two parellel yellow ribands to 
be seen across the land following the irregular course 
the wagon had taken. It was a most striking sight. 
There was not another Charlock to be seen in the 
field. The seeds producing these beautiful yellow 
ribands had been buried fifteen years."— Ibid, 
