MONITORING NUTRIENTS & SALT
Other Methods

There are two ways to take a soil solution sample. The first is to bury a porous ceramic cup, apply a vacuum to it and then return later to extract a sample. The second is to collect soil water 'passively' using a device like a FullStop.

The composition of the soil solution from a FullStop can be different from the soil solution extracted from a ceramic suction cup. The FullStop takes a sample of water that is moving through the profile. The suction cup extracts water from the soil whenever the suction is applied; sometimes the sample represents ‘moving’ water and sometimes the sample represents water resident in the smaller soil pores.

The time the sample is taken is important. As the soil dries the salts in the soil concentrate. Therefore to make sense of trends from suction cups you need to know the water content at the time of sampling.

The FullStop always takes a sample under similar conditions i.e. when a wetting front of strength 2 to 3 kPa passes. This makes the EC and nutrient trends more meaningful, because samples are taken at similar water contents.