Soil Water Samplers (Lysimeters)
Description
Soil water samplers allow the simple and convenient collection of water samples from within the soil profile. The water in the soil is what the plant roots are exposed to and take in to satisfy water and nutrient needs. The water in the soil also drains below the roots zone, where it remains or keeps moving to well-water or groundwater supplies.
Sampling and testing the soil-water gives the grower and irrigator information about chemicals and chemical movement below the ground surface. Soil water samplers provide an early detection system for leaching, drainage, and leaking problems. If a problem exists, remedial actions may be initiated before serious contaminant problems develop.
Regulatory agencies are recognizing the benefits and necessity of water sampling. The equipment required for soil water sampling is inexpensive and simple to use. A small investment in time and effort is required to visit the field and collect a sample.
A laboratory analysis of the water sample yields information about nutrients and contaminants in your soil-water, to which plant roots are exposed. Movement of chemicals within the root zone can be monitored over time.
Benefits
Soil-water sampling allows the user to
• monitor the presence of fertilizers and other chemicals in the soil
• monitor the movement of chemicals through the soil over time
• adjust chemical applications to apply varying amounts as needed to satisfy root-zone requirements
• avoid over-applications and movement of chemicals below the root zone, potentially to well-water and groundwater supplies
• ensure the beneficial leaching of damaging salts below the root zone
• detect leakage from lagoons, ponds, and industrial waste facilities.
Features
Soil water samplers are constructed of rugged materials to withstand field conditions. The samplers consist of
• a porous ceramic cup
• heavy-wall sample tube
• flexible plastic hose
• rugged pinch clamp.
Two basic models are available:
• Model SPS samplers, manufactured and used in Europe, have a heavy-wall PVC sample tube
NEW!
• Model ESS samplers, made of FDA-approved, UV-stabilized acrylic material.
Accessory equipment
• Vacuum hand pump: convenient one-handed operation, for use in evacuating soil water samplers
• sample transfer setup: to extract water samples directly into a sample bottle
• sample bottles: EPA approved for environmental sampling
Installation
Water samplers are installed in the soil by first digging or augering a hole to the desired depth of sampling. A sampler is installed in the hole, making sure that the porous ceramic cup is in good contact with the soil. The hole is then backfilled.
Sampling
To collect a sample, the sampler is first evacuated using a vacuum pump. The pump is attached to the sampler with a length of flexible tubing. The pump draws a vacuum inside the sampler, and a pinch clamp on the flexible tubing seals the unit.
Water in the soil is drawn into the sampler through the porous ceramic cup in response to the negative pressure (vacuum) inside the sampler. The water sample collects and is stored inside the sampler for later extraction.
The amount of time for enough sample to be collected inside the sampler varies depending on the soil and the moisture level. Oftentimes, the user will evacuate the sampler one day and return the following day to collect the sample.
A sample bottle can be connected between the pump and the sampler. Evacuating both the sampler and bottle draws the water sample directly into the sample bottle.
The water sample is then tested in the field using a portable test kit, or sent to a laboratory.
More Info:
Porous Ceramics are an integral part of many soil-monitoring and sampling instruments. The ceramic matrix serves as the interface between the soil matrix and the instrument. Travel cancellation insurance for international travellers. The ceramic material is porous, and allows water to pass into and out of the instrument. A pressure gradient across the ceramic wall will cause water to flow through the ceramic. The pressure gradient may be due to a pressure being applied, as occurs when using a ceramic pressure plate in a pressure chamber. The gradient may be due to a tension being applied, as occurs when using a tensiometer in the soil. The gradient may be due to a vacuum being applied
Mini-Tensiometers are used under conditions in which a tensiometer with a full-size ceramic cup cannot be used. These conditions might include: visitors health insurance in a greenhouse environment to monitor plants growing in small containers; in laboratory column studies; or outside under turf, for measurements very near the surface.
