More potato questions?

[einstein]

Whats the ideal ph for spuds? would 5.5 be ok?
Also how long will a new potato keep for..in a fridge... before it loses its new pot texture and taste. Had some jerseys tonight and they were pretty average...even though I guess they must be new season.

 

[DrWazzock]

I am no expert but:
I think 5.5 will be ok.
The only problem with keeping them in the fridge is that the starch will turn to sugar at low temperatures and they would fry darker(burn easier). Not that you would be frying jersey royals.
Commercial new potatoes are often a bit tasteless due to being forced on. It’s also variety, soil, manure and storage dependent.
I like Sharpes Express for the garden. If you are going to trouble, select a firmer tastier variety, not a watery flavourless commercial.
Or put a sprig of mint in the pan and eat them cold having melted plenty of butter on them before they cooled.

 

[Bogweevil]

pH5.5 is pretty good for spuds but generally wise to lime for the sake of the rest of the rotation aiming for pH6.5. Apparently it is a myth that lime worsens common scab.

New potatoes lose flavour very quickly but will keep for a little while. The lack of set skin means they dry and then rot quite quickly. 3-5 days in fridge perhaps.

 

[David.]

A Scotsman once knew would only use sulphate of potash in potato blend, he said that the acidifying effect reduced scab and improved potato skin appearance.

 

[Bogweevil]

A Scotsman once knew would only use sulphate of potash in potato blend, he said that the acidifying effect reduced scab and improved potato skin appearance.

I think he meant sulphate of ammonia which unlike SOP is acidic in reaction. It might work, tho experiments adding sulphur to rows were ineffective in preventing common scab. Shame, would save a lot of irrigation.

 

[DrWazzock]

I understood muriate of potash tended to prune the roots and reduce tuber numbers which is why SOP was preferred source of potash. But if you wanted fewer bigger tubers use MOP.

 

[Bogweevil]

I understood muriate of potash tended to prune the roots and reduce tuber numbers which is why SOP was preferred source of potash. But if you wanted fewer bigger tubers use MOP.

I don't know about pruning the roots, a very interesting idea, but SOP generally makes for better quality spuds and indeed more, smaller tubers. Potash Development Association says:

Applying large amounts of potash fertiliser generally reduces the dry matter (DM) content of tubers by up to 2%. The effect of K supply on tuber DM appears to vary greatly with variety. Where DM is important and levels need to be improved when muriate of potash (MOP, potassium chloride) is being used, splitting the total requirement to half in the autumn and half in the seedbed can help. Switching from MOP to SOP (sulphate of potash) applied in the spring may have a greater effect than splitting the MOP application and may improve DM by up to 2%. DM is affected to a greater extent by factors such as N supply, irrigation and variety.

Both specific gravity and starch content tend to follow dry matter and where these characteristics are important it is necessary to ensure that the correct amount of K is applied and to consider the use of SOP rather than MOP.


Form of potash and quality

		MOP	SOP
	Yield	Increased	Increased
	Dry Matter	Decreased	Decreased less
	Specific Gravity	Normal	Higher
	Starch	Lower	Maintained
	Fry colour	Improved	Improved less
	Fat absorption on frying	More	Less
	Tuber numbers	Normal	Increased
	Tuber damage	Reduced	Reduced
	Internal blackening	Reduced	Reduced less
	Flavour	Normal	Better
	Cracking on high pH soils	Normal	Less

Yield response to potash is normally associated with an increase in average tuber size and weight. The use of sulphate of potash instead of muriate of potash may be beneficial where larger numbers of small-medium size tubers are required such as for seed, canning, salad etc. The benefit will be more pronounced under dry or stressed growing conditions.

 

[Lowland1]

pH5.5 is pretty good for spuds but generally wise to lime for the sake of the rest of the rotation aiming for pH6.5. Apparently it is a myth that lime worsens common scab.

New potatoes lose flavour very quickly but will keep for a little while. The lack of set skin means they dry and then rot quite quickly. 3-5 days in fridge perhaps.

Our soil at home has a PH of about 5.6 and was perfect for potatoes but not much good for corn so of course we had to use lime so we would put on about 2-3 tonnes an acre of powdered lime. one run up the field with the potato harvester found the place where the lime had been dumped the year previously and every potato for 20 yards came up scabbed.