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The vacuum within the Sampler causes the water to move from the soil, through the pores of the porous ceramic cup, and into the Sampler. The rate at which the soil solution will collect within the Sampler depends on the capillary conductivity of the soil, the soil suction value within the soil (as measured with tensiometers), and the amount of vacuum within the Sampler. In moist soils of good conductivity, at field capacity (10 to 30 cb of soil suction as read on a tensiometer) substantial soil water samples can be collected within a few hours. Under more difficult conditions it may require several days to collect an adequate sample. Recovering a Sample from In general, a vacuum of 50 to 85 cb is normally applied to the Soil the Soil Water Sampler Water Sampler. In very sandy soils, however, it has been noted that very high vacuums applied to the Soil Water Sampler seem to result in a lower rate of collection of the sample than a lower vacuum. It is our opinion that in these coarse, sandy soils, the high vacuum within the Sampler may deplete the moisture in the im- mediate vicinity of the porous ceramic cup reducing the capillary conductivity, which creates a barrier to the flow of water to the cup. In loams and gravelly clay loams, users have reported collec- tion of 300 to 500 ml of solution over a period of a day with an applied vacuum of 50 cb, when soils are at field capacity. At waste water disposal sites, users have obtained 1500 m1 of sample solu- tion in 24 hours following cessation of irrigation with 1 to 2 inches of waste water on sandy or clay loam soil. To recover a soil water sample, remove the Pressure-Vacuum tube from the vacuum port of the pump, and attach the tube to the pressure port. Place the discharge access tube in a small collection bottle and remove both clamping rings. Apply a few strokes on the hand pump to develop enough pressure within the Sampler to force the collected water out of the Sampler and into the collection bottle (see Fig. 11). Figure ll. Subsequent samples are collected by again creating a vacuum within the Sampler and following the steps as outlined above. SOILMOISTURE EQUIPMENT CORP. 14 ^® P.O. Box 30025, Sonto Borbora, Colifornio 93105 USA / \ Phone: (805) 964-3525 ~ Fox: (805) 683-2189 soILM\ olsttlRE e-moil: soles®soilmoisture.<om • Web: http://wwwsoilmoisture.com ~/