If water for irrigation is passed through a magnatic field ,will the resulting "wetter" water increase the yield of a crop. say - potatoes?
Salesman
This is a technique that is most typically used in fabric cleaning to allow more water to enter into the pores of the textiles. I know that it also been hyped as a health aid. The importance of reducing the surface tension of water would only be important in agriculture at what is commonly called the 'wilting point' or the point at which the plant cannot draw any more water from the soil to its roots for a variety of reasons. Theoretically, decreasing the surface tension of water would aid the plant in drawing more water to the roots, but at the wilting point you would have a lot of other factors that would need more attention first. Besides, I doubt that there could be an economic benefit once you compare the energy neccessary to create the magnetic field through which the water is passes, and the benefit you would see (if any) from increased production.
The hype that 'wetter' water carries more nutrients has not been scientifically proven, and besides, in the soil matrix there is more at work that influences soluability than the surface tension of the water. The benefit of increasing the nutrient content of the water is also highly dependent on conditions inside the soil such as pH, which will have a much stronger influence on nutrient availability.