lots of foliage.... small to no potatoes why?

Lots of foliage.... small to no potatoes, why?

Half the plot was planted the normal way, burying the seed and hilling. The other half was just tossed on the ground, lightly stepped on and covered with straw.

They were watered once a week unless it rained.

The foliage was awesome… lots of blossoms. The plants yielded marble size to no potatoes.

Since we have no other place to plant taters this makes the 5th cropping in 5 years in the same place.

If you have been successful with burying the seeds and getting some average size potatoes during other years grown right in the same place.

Then it is very possible that the soil has been drained of a certain nutrient, the potassium (or another equivalent form called potash).

You should check the ph of your soil, it should be anywhere around 5 to (nearly) 7. If the ph is too acidic, meaning less than 5, then mix some wood ashes to increase the ph.

On the contrary if the ph is too alkaline, more than 7, then add some peat moss or compost as well.

As you mentioned, the plants had a lot of green foliage which implies that the soil has enough nitrogen in it.

A high nitrogen fertilizer can make the plants produce more foliage, consequently focusing on the green parts and limiting the potato development.

As an alternative you could use some organic fertilizer, which should be lower in nitrogen compared to phosphorous and potassium.

These macro-nutrients are generally labeled in the front with N-P-K (nitrogen, phosphorous, potassium).

How to increase potato yield

Many people change the crops after harvesting potatoes, that is called rotation planting.

The main purpose is to avoid planting the same kind for 2 years in a row and follow a certain sequence when growing the plants to prevent diseases and drainage of nutrients. 

For example, in the rotation root vegetables and vegetables in the nightshade family which includes tomatoes, shouldn’t be planted on that soil following a potato crop.

A very basic example of a common sequence beginning with the nightshade vegetables with the exception of potatoes, then legumes which are beans, lentils and peas among others.

Then the root crops which include carrots, beets and also the potato (tuber). And then the cruciferous vegetables: cabbage, kale, cauliflower, broccoli.

Don’t forget to avoid planting tomatoes and potatoes together as they can get the same diseases.

Also remember that you can start growing potatoes in containers while the soil is being amended for the cultivation.