Question
Dear tom,i am a beginner at growing my own vegatables and things are coming alone great,all that is apart from my very small yeild of potatoes,i planted  seed potatoes that i brought from store.can you give me any advice to improve my harvest? thank you for your time,regards marion

Answer
Hi Marion,
Thanx for your question.  For good potato production you need soil that has good tilth (the texture is soft and crumbly and doesn't lump together because of too much clay but is not too loose and sandy).  The bed needs to be tilled deeply.  What you do is till deeply and then make deep furrows in which you place the seed potato and cover.  As the plants grow, you continue to hill up the soil along the sides.  You can also use straw to increase the density around your potato plants.  Hilling up around the potatoes creates more of an area for the tubers to grow.  Also, when fertilizing you  need a fertilizer that is lower in nitrogen.  High nitrogen fertilizers will cause vigorous green growth with little or not growth in the roots, tubers, etc.  Look for fertilizers with the following ratings 6-24-24 or 8-24-24.  Also, heap well-composted manure around the potato hills which adds nutrients and body to the soil.  I hope this helps.
Tom

P.S.  We also have a category here at Allexperts called Growing Vegetables.  I know a little big about vegetable growing but you might want to tap into this resource of "real" vegetable growing experts.  Regards.