Fertigation in the field must be carried out with very practical and efficient systems. It is very unlikely to have electric energy available and this is why it becomes difficult to supply complex fertigation control units which operate in proportional system or in E.C.
The best systems in open field are the QUANTITATIVE ones like the FERTILISER TANK and the VENTURI INJECTOR.
They are going to distribute the quantity of fertilisers in a well calculated and precise way based on the surface of the sector. Both systems operate with differential pressure and therefore exploit the irrigation water pressure without the need of external energy.