Rational Potato Culture. 
409 
per acre. In no case was the crop less than 1 1 tons per acre, while 
in some it exceeded a rate of 30 tons per acre. The crop of 119 
cultivators in this group fell below 11 tons per acre, but their 
average yield is not given. 
The principal points insisted upon by M. Girard to ensure 
success in potato culture are, 1 in the first place, deep cultivation and 
preparation of the soil before the seed is planted. Like the beet root 
and mangel-wurzel, the potato requires a deep and friable tilth. Its 
roots run far into the soil in search of available food, if it has been 
properly and deeply stirred. M. Girard advocates the deep ploughing 
of potato land in winter with a plough going 8 inches deep, followed 
by a subsoil plough moving the soil 6 inches deeper. Manure is put 
on in the early spring and ploughed in. The furrows are then 
harrowed down and the potatoes planted as soon as the chances of 
the sets being frozen are past. The date of planting must vary 
according to the season and the climate of the district. M. Girard 
thinks that 13,200 plants per acre are sufficient for varieties of full 
habit of foliage, or a plant every 19| inches in rows 23§ inches apart, 
which would give 13,200 plant-centres per acre. For other varieties 
a distance of 21 § inches in rows set 21 1 inches apart is advised, 
giving 16,000 plant-centres per acre. 
Manures. — M. Girard’s dressing of farmyard manure is from 
8 to 12 tons per acre. He also adds 2^ cwt. of superphosphate of 
lime and from 1^ to 2^ cwt. of sulphate of potash per acre, put on at 
the same time as the farmyard manure. From 1| to 2 cwt. of nitrate 
of soda per acre are sown broadcast in May, after the plants are 
up ; but M. Girard prefers to apply half of this dressing in May and 
half in J uly. 
He advises the careful selection of seed from vigorous and 
fruitful stocks. It should be of even size, weighing from 2| to 4^ oz. 
for heavy cropping varieties, and from 1-| to 2| oz. for ordinary 
kinds. Seed should be planted whole. The experiments made under 
Mi Girard’s supervision would appear to prove that it is wrong to 
cut seed potatoes. 
The most careful and constant hoeing is advocated in order to kili 
every weed. Moderate earthing is recommended, particularlyforthose 
large cropping varieties whose tubers tend to work up to the surface, 
and become green from the action of light. This, indeed, appears to 
be the origin of earthing and, as many hold, the sole reason for 
the practice. 
Dressing the plants with sulphate of copper mixture as a pre- 
ventive measure before disease appears is deemed essential by M. 
Girard. His receipt for this is — 
4 lb. 6 oz. of molasses mixed with 11 gallons of water. 
4 lb. 6 oz. of sulphate, of copper dissolved in this water. 
6 lb. 9 oz. of lime slaked and put in 11 gallons of water. 
1 Amelioration de la Culture de la Pomme de terre indvstrielle et fourrag'ere, 
par M. Aime Girard. Instructions pratiques. 1893, 
VOL. IV. T. S. — 14 E E 
