55 
Thd Effect of Weeds upon Cereal Crops. 
The seeds were planted in eight clumps round each pot, the 
wheat and weed being placed alternately in the mixed pots. Two 
wheat seeds were dibbled in each hole, the weaker plants being 
thinned out later, and a small pinch of weed seed was likewise 
dibbled in per hole, but no thinning was done, all the plants being 
allowed to take their chance of reaching maturity. The pots were 
placed in the open air under the shelter of a gauze cage to protect 
them from the depredations of birds. Water was supplied when 
necessary, and the crops were harvested on August 5th and 6th. 
The shoots were cut off as close to the surface of the soil as possible 
Then, pot by pot, the earth was carefully thrown out on to a rick- 
cloth and was sifted to disengage the roots as far as possible. The 
soil was then returned to the original pots in readiness for the 
second crop (Experiment 2). Prior to harvesting, the heights of 
the various plants were taken and the number of fruiting heads or 
ears recorded for each pot. The time of cutting was determined 
by the fact that the weeds had all reached maturity and were ripening 
their seeds, though the wheat was still immature and had not been 
long in ear. 
SOIL A. TOTAL DRY WEIGHTS OF CROPS IN SIX POTS. 
Shoot. 
Root, 
Crop. 
Weed. 
Wheat + 
Weed. 
Grams. 
Grams. 
Grams. 
Papaver-)- Papaver 
52-4 
110 
(5potsooly) 
26 0 
82-2 
Wheat-)- Papaver 
11-9 
89-4 
Wheat + Wheat 
32-7 
70-8 
W’heat + Alopecurus 
22-2 
29-3 
Alopecurus-)- Alopecurus 
750 
15-7 
AVERAGE DRY WEIGHTS OF SHOOTS. 
Crop. 
Weed. 
Per plant. 
Per single sowing. 
Per single sowing. 
Grams. 
Grams. 
Grams. 
Papaver-f Papaver 
5-24 
3-425 
13-7 Wheat-)-Papaver 
1-98 
1-863 
7-45 Wheat + Wheat 
2-950 
11-8 Wheat + Alopecurus 
3‘70 
Alopecurus + Alopecurus 
6-25 
(A single sowing is the quantity of wheat or weed sown in the mixed pots). 
