for the Groicth of Undiscased Potatoes. 
395 
I)ut 18 tons per acre, on an averag-e of the four late varieties' 
nnd 27 tons for one of these varieties (No. 3), are remarkably 
hoavv yields. On the other hand, at Ayr, the same quantitv 
of seed, planted nearly three times the space, and while a heavier 
vield, weight for weight, was secured, the estimated produce, 
per acre, fell to 8f tons. 
It appears then from these and other instances, which an 
examination of the Tables will show, that the potato which 
starts with a large supply of food in the tuber, and secures by 
its help a good hold on the soil and a good mass of foliage in 
the air, produces the most remunerative crop. The multiplication 
of the seed in these experimental crops hy cutting the tubers, 
means, of course, nearlv the same as occupying a large plot ; for 
as the space allowed by the different growers for each sett was 
tolerably uniform, and as the number of seed-tubers was practi- 
cally the same throughout, the necessity for a large plot was due 
to an artificially increased number of setts. The Tables in this 
view confirm the conclusion already stated, that a given weight 
of seed may be so spread out as greatly to reduce the yield, per 
acre, of the crop, even though the setts are not widely separated, 
but placed at a moderate and uniform distance from each other. 
The average space allowed to each sett is from 2\ to 3 square 
feet. This is somewhat more than the space which Mr. Maw- 
determined to be the most profitable distance. His experiments 
showed that to give more than 2 square feet to each sett, gave 
no advantage in the shape of an increase of weight. It deserves 
the consideration of growers, in the face of his results, whether 
too large a space is not given to each sett, and the produce, per 
acre, accordingly reduced. Thus, to take the most extreme case 
in these experiments, had only 2 square feet been given to each 
sett in the Essex locality, the produce of No. 3 late might have 
been 16 instead of 7 tons. 
The varieties of soil supply no sufficient explanation of thr> 
difference in amount of produce, although the richest soils exist 
in the localities which produced the heaviest crops. 
It is still more remarkable that heavy manuring has not pro- 
duced a corresponding result in the weight of crop. The experi- 
ments of Dr. Voelcker and the experience of growers point to 
the dung of the farmyard as the best potato-manure. Neverthe- 
less, we notice that 40 tons of this manure, with 5 cwt. of super- 
phosphate applied as a top-dressing, produced 5 tons per acre in 
Munster, while 25 tons, without any artificial manures, gave a 
crop of 18 tons per acre in Staffordshire. It is, however, certain 
that the most successful potato-growers use a large amount of 
manure. 
Note. — By a printer's error in Table IV., Leinster and Ulster are numbered 18 
and 19, instead of 19 and 20 as in the other tables. 
2 D 2 
