rOTATO-GROWIN(J EXPEEIMENTS. 
297 
longer than on the plot which received no potash, and the saleable potatos 
were much larger. 
(b) Muriate of potash versus kainit. 
Muriate of potash gave a heavier yield than kainit by 23^ cwt. : this 
increase was in saleable potatos and was valued at £'3. 12s. per acre. 
These results are confirmed by last year's, when muriate of potash 
gave a yield of 19 tons 14 cwt. 1 qr., and kainit gave IG tons 13 cwt. 
1 qr., a difference of 3 tons 1 cwt., or £0 3s. per acre in favour of 
muriate of potash. These results have also been confirmed by the 
experiments carried out at Cockle Park, Northumberland, under Professor 
Somerville, where kainit gave a yield of 3 tons per plot, sulphate of 
potash 3 tons 6 cwt., and muriate of potash 3 tons 17 cwt. of saleable 
potatos. 
The results at Holmes Chapel last year were — • 
Both muriate and kainit gave good-sized saleable potatos, but those 
grown with muriate of potash were larger, the haulms were also stronger 
and remained green longer. The percentage of saleable potatos was 
slightly in favour of muriate of potash by 0*75 per cent. 
We believe that the form of potash has a good deal to do with these 
results. Kainit is in the crude state as procured from the mines ; the 
potash contained in it is practically all in the form of sulphate of potash, 
but besides it contains large quantities of common salt (about 33 per 
cent.) and smaller percentages of magnesium chloride and magnesium 
sulphate. It is liable to injure the young rootlets of the potatos if 
applied at the time of planting, as both chloride of sodium and 
magnesium chloride in quantity are hurtful to roots. The poor 
returns from kainit may be due to this, and probably if applied a con- 
siderable time before planting the results might be different. 
Kainit is usually the most expensive potassic manure, if calculated 
according to the unit value ; besides, the carriage is a serious item, as one 
ton of kainit contains about 12 per cent, of potash, and one ton of 
muriate will contain 60 per cent., or, to put it in another way, one ton of 
muriate of potash will contain as much potash as five tons of kainit 
and only cost one-fifth of the carriage. 
Muriate of potash is a manufactured product containing from 50 to 
60 per cent, of potash, and guaranteed 80 to 96 per cent, purity. Its 
chief impurity is common salt, but if you get it containing 96 per cent, 
of muriate of potash it practically contains no impurities. We believe 
this is the reason that muriate gave better results than kainit. 
Sulphate of potash is also a manufactured product containing 50 per 
cent, of potash and guaranteed to consist of 95 to 98 per cent, pure 
sulphate of potash. It is not so diffusible as muriate of potash in 
the soil. 
(c) Double quantities of muriate of potash. 
The application of 1 cwt. of muriate of potash gave better results 
than when 2 cwt. were applied, the increase being 3 tons 11^ cwt., 
For kainit 
Sulphate of potash 
Muriate of potash 
16 tons 13 cwt. per acre. 
18 16 ,, „ 
19 J, 11: 5, ,, ,, 
