Getting started with potatoes – Part 2

Bill Kerr discusses fertilisation and pest control.

Whether you have chosen manure or chemical fertiliser, use it generously. The results will be well worth the extra cost.
Photo: Bill Kerr

Unlike most vegetables, potatoes do not have a large root system relative to the amount of leaf growth, so you should adapt your fertilisation and irrigation accordingly. Apply fertiliser to the furrow before planting. If manure is available, work it into the soil before planting, ideally a few months before. If the soil has not previously been adequately fertilised, it’s better to combine poultry and cattle manure.

Broiler chicken manure can be applied at 2kg and egg production manure at 1kg. Cattle manure can be applied at 4kg/m² to 5kg/ m². Work the manure into the soil, so that when you’re ridging in preparation for planting (see last week’s issue), this fertilised soil will end up in the ridge where the potato roots will grow.

If no manure is available, use chemical fertiliser. This will be more expensive and less healthy for the soil, but potatoes are highly productive and require plenty of nutrients to perform well. Apply one handful of 2:3:4 (30) per running metre of row in the furrow, and cover with a layer of soil or lightly hoe the soil to prevent the tubers from being in direct content with too much fertiliser. Don’t skimp on fertiliser to try to save money!

The soil is now ready for the tubers, which are just starting to sprout. Depending on their size, these can be spaced  25cm to 35cm apart in the furrows. They should be between the size of a hen’s egg and about twice this size.

Covering the tubers
Once the tubers are in place, cover them by levelling the ground by hand or by using a tractor. If you have access to a tractor, use a plough with double mouldboard. Run the tractor down the ridges; the soil will be thrown into the furrows by the implement, leaving a slight furrow between the rows of potatoes. There’s no need to go too deep – simply cover the tubers with 5cm or so of soil.

Weeds and insect pests
After irrigating, spray the entire area with a suitable pyrethroid insecticide to eliminate cutworms and millipedes. Cutworms can do a great deal of damage after the shoots appear above the surface and it’s not worth taking a chance with this pest.
Millipedes can also damage the tubers, eating holes in them underground. At this stage, it’s difficult to control them, so get rid of this pest right at the start.

Herbicide may not be necessary if the weed growth is fairly sparse. If you must spray herbicide, there are several types to choose from. First spray water with a full knapsack sprayer to calculate the area to be covered and how much herbicide to put into the tank. You can add the insecticide to the herbicide to accomplish both tasks in one go.