Wash it or let it leach in the rain

It was traditional to use seaweed to fertilise gardens in the islands in Denmark until a few decades ago.

There the seaweed is first spread out in a layer in a meadow or on the higher part of the beach until it has been washed by several rainshowers.

By washing soluble Na will leach out from the seaweed. At the same time, most of the elements suppose to be essential for amendment may also be lost.

The practice has been successfully used for centuries. It seems there are enough nutrients and organic matter left to make the rain washed seaweed a very good fertiliser.

Dr. Milham and Dr. Andersen, If i understood your response properly, i think you are both referring to freshly collected seaweeds being washed properly with water or rain-showers for Na conc reduction which is correct. However, i think Dr. Oluwadare is more particular about Na reduction from the powdered form. At this level, i believe the period of drying, processing nd conversion of seaweed to powdered form would have reduced the Na concentration to permissible limit. Wrong? 

I am talking about washing the more or less fresh plants. If they are first made into a powder I think they  will leach a lot of organic and inorganic matter with the washing. 

Sea weed contains besides sodium, other essential plant nutrients and organic matter, which can not be ignored. I suggest to mix the sea weed with plant ash since the latter is rich in potassium to balance or offset the harmful effects of sodium. Mixing can be in 3:1 (Sea weed to Ash) ratio by weight. 

What is the sodium content of washed seaweed? Is it higher than that of other vegetation?

Thank you all for your contributions. But I like to add that the seaweed is already in powder form, therefore leaching off the high Na content might not be feasible again. Your contributions are appreciated, Please I'm still expecting more. 

Can I just ask what is the sodium content of your powdered seaweed? What is it after you have washed it in water?