ilangeeran wrote:I need to build a data logging device using raspberry pi. it should log the values of nitrogen, phosphorous and other mineral content. i dont know which sensor to use. help me regarding this....
You might get best&reliable results with chromatography. Sensors (called detectors) in LC are light-based - you detect absorption at various wavelengths related to time a material (each fraction) is capable to pass a separating colon.
P.S. If you'll continue to use complete colored and bolded text in your messages, I'm going to ignore them !
Best wishes, Ivan Zilic.