NOTES AND ABSTRACTS, 
199 
Nitrate Content of a Soil subjected to Temporary Drying Increased. By 
W. Buddin {Jour. Agr. Sci. vi. pp. 452-455). — Soil spread out and dried in 
the laboratory for twenty-four hours was found to contain more nitrogen than 
the same soil not dried. No satisfactory explanation of this difference has yet 
been found. Twenty-four parts in the million of soil in the unspread were 
raised to twenty-six and thirty, and the increase was augmented after re-moisten- 
ing, while the numbers of bacteria were not increased. — F. J. C. 
Nitric Nitrogen Content in the Country Rock. By R. Stewart and 
W. Petersen (U.S.A. Exp. Stn., Utah, Bull. 134, June 1914 ; 16 tables). — Some 
further studies on the cause of the excessive nitrogen found in certain agri- 
cultural soils in the States of Colorado, Utah, and Wyoming. 
It is found that the country rocks contributing to the formation of the soils 
are heavily impregnated with nitrogen, some of them being much richer than 
the Chile sodium nitrate deposits. 
These nitrogenous soils are also found to be exceedingly rich in alkali salts. 
The richest deposits are found in the cretaceous shales, and it is estimated that 
these shales contain 90,000,000 tons of sodium nitrates. 
Thus in the dry States irrigation from these sections has not only increased 
bacterial activity but is also adding nitric nitrogen by depositing same from 
the water. — C. P. C. 
North American Forest Trees in Britain. By Prof. A. Henry (Trans. Roy. 
Scot. Arbor. Soc, xxix. pt. 2, pp. 156-164; 1915). — Exotic trees are abso- 
lutely necessary for the economic production of timber in the British Isles. 
This is admitted in practice, and is sound in theory. Our native species are 
few in number, all being late immigrants from the continent of Europe after 
the glacial epoch, and are by no means those that are most suitable to the climatic 
conditions of the present day, or that are most fit for producing, as quickly 
as possible, valuable timber. 
The Scots pine, our solitary forestry conifer, was widely spread over the 
British Isles in the dry, warm continental climate that prevailed at the beginning 
of the neolithic period ; but it has, with the advent of our present humid, cool 
climate, gradually disappeared from all parts of the islands, except in the great 
mountain massif of the Scottish Highlands. It is at the present time distinctly 
a tree for use in certain districts only, characterized by a low annual rainfall 
and much sun in late summer and autumn, as in Speyside and Deeside in the 
north, and in the sandy heaths of the south and east of England. In such 
districts it regenerates freely, and attains a great height, producing a satisfactory 
volume of timber of good quality. — A. D. W. 
Orchard Experiments in Pennsylvania. By J. P. Stewart (Exp. Stn. Penn- 
sylvania, U.S., Bull. 134, 20 pp. ; 3 figs.). — A summary of various experiments. 
Various methods of root grafting show no practical difference. The selection 
of grafts from superior individual trees so far fails to show any advantage, as 
has been demonstrated elsewhere. Experiments in top grafting are interesting, 
but the varieties used are not commercial sorts of this country. Dynamiting 
the soil before planting gave no definite results as against normal planting. 
Manurial and cover-crop experiments are also reported. — E. A, Bd t 
Pea Aphis in 1914, Control of Green. By L. B. Smith (Exp. Stn. Virginia, 
Bull. 13, Oct. 1914; 1 fig.).- — This aphis (Macrosiphum pisi Kaltenbach) is 
one of the most troublesome and destructive insects with which growers of 
market-garden crops in Virginia have to contend. It passes about eight months 
of the year on clover (especially red) . The varieties of peas grown for conducting 
the spraying experiments were ' Gradus,' 'Thomas Laxton,' 'Nonpareil,' and 
' Pilot.' The plants became infested with the aphids during the last week in 
April, coming from a field of crimson clover lying next the peas. The most 
satisfactory sprays were : 
No. 1, " Black-leaf 40 " (nicotine-sulphate) . 10 ounces 
whale-oil soap . . , 4 lb. 
water , . . . . .50 gallons 
No. 2. Whale-oil soap . . . . 5 lb. 
water . , . . . . .5° gallons 
It is necessary to spray within a day or two after the aphids first appear on the 
pea vines. Two or three sprayings may be required, especially in bad cases, 
the second application to come about a week after the first, — V. G. J, 
