SECTIONAL TRANSACTIONS.—M. 468 
12. Mr. R. A. Fisuer.—tIncidence of Rainfall in Relation to the Wheat 
. Crop. 
13, Dr. G. P. McRosrie.—Some Forage Crop Needs and Difficulties in 
Canada. 
14. Mr. F. L. Excrevow.—A Spacing Experiment with Wheat. 
The experiment was one of a series aimed at the identification of those 
characters of different wheat forms by which their yielding capacities are mainly 
controlled. True plant characters—the vital processes—are not sufficiently under- 
stood to be the subject of such an inquiry. Consequently ‘ algebraic characters ’” 
like tillering and ear size were observed. Such characters are much affected by 
inter-plant spacing, and that is the first ground of necessity for making spacing 
experiments. The second is the fact that field crops, inevitably, are aggregates 
of a great number of spatial intervals. Plant growth and yield in the field 
consequently must depend largely upon the adaptability of each particular wheat 
form to the various spacing intervals encountered in field crops. 
Two wheats were grown each at five spacings, and special measures were 
taken to secure uniformity of material. 
Analytical data are produced to show that :— 
1. The variability of yield per plant and yield per unit area with spacing 
can be resolved in terms of tillering, ear size, and grain size. 
2. Ear size and grain size bear distinctive relations to tillering which are 
characteristically different in the two wheats. 
3. Data of the kind discussed appear to offer an approach to the differences 
in yielding capacity displayed by the various forms of wheat in the field. Upon 
the discovery of these differences must depend the possibility of breeding higher 
yielding forms by orderly ‘synthetic ’ aggregation of desirable characters by 
means of hybridisation. 
ec. Ge. OCOMrT Rosertson.—Field Experiments with Rock 
Phosphates on Soils Poor in Phosphoric Acid. 
The paper gives an account of a number of field experiments carried out in the 
six counties of Northern Ireland to ascertain the fertilising value of ground rock 
phosphates compared with high grade basic Bessemer slag and superphosphate. 
The experiments were carried out during the years 1921, 1922, and 1923, and are 
still in progress. The crops were turnips, potatoes, oats, and hay. The results show 
that on the turnip crop as good returns may be expected, on all but peaty soils, from 
ground rock phosphates as from superphosphate or high-grade slag. Contrary to 
expectations, superphosphate proved the most effective type of phosphate on peaty 
soils. On potatoes superphosphate proved to be decidedly the better phosphate. 
On the oat crop the best returns were given by basic slag, rock phosphate and super- 
phosphate being equally good and not far behind the slag. 
The experiments confirm the view that ground rock phosphates may, under the 
soil and climatic conditions of Northern Ireland, be regarded as an effective substitute 
for the rapidly disappearing high-grade basic slag. It is possible that the effectiveness 
of rock phosphates on the potato crop may be enhanced by still finer grinding. 
Wednesday, August 13. 
16. Joint Discussion with Section K (g.v.) on Forest Problems in 
Canada. (Page 454.) 
