Technical specification and construction
Horizontal test tube soil sampler parts: 1-1 = base; 1-2 = hole; 1-3 = bay; 1-4 = upright shaft; 1-5 = pin; 2-1 = furrow; 2-2 = hole; 2-3 = hand-push piston; 2-4 = pin; 2-5 = piston head; 3 = folding ruler; 3-1 = pin; 3-2 = hole; 3-3 = rivet; 3-4 = hole.

The sampler has two parts: a stainless steel folding ruler (part #3) and a hand-pushed piston (parts #1 and #2) made of a 10-mm-thick aluminum base (part #1) and a hard PVC piston (Part #2). The cross-shaped base provides a large contact area with the soil and minimizes the damage to the plants. To fit the test tube, an 18 mm diameter hole (1-2) was drilled in the center of the base and extended on both sides to form a 60 mm long, 12 mm wide bay (1-3) for viewing the sampling area. Two upright piston shafts, 10 mm thick, 110 mm long (1-4) were Aragon-welded on both sides of the central hole to fit into two 10.2 mm furrows (2-1) on the PVC piston. Thus, the piston can move freely along the shafts. Two stainless steel pins, 50 mm long; 8 mm in diameter (1-5) are screwed to the upper part of the shafts and two similar pins to the piston at its lowest part (2-4) to prevent separation of the piston from the base. The piston is equipped with a rounded, flat PVC head, 120 mm in diameter, for easy holding (2-5). Additionally, a hole, 16 mm in diameter and 7 mm long, was drilled into the piston base and a soft PVC was glued into its far end to form the proper receptacle for a standard polyethylene tube. The hand-pushed piston weighs 1.5 kg. The second part of the tool is a 2 mm thick stainless steel folding ruler (3) covering 200 x 50 cm when open and 43 x 28 cm closed. The ruler is constructed from segments fitted together with stainless steel rivets (3-3) to provide 360° movement. When the ruler is unfolded, 11 holes, each 2 cm in diameter (3-2) were drilled, spaced 32 cm apart in a zigzag pattern covering a sampling area of 1 m². Finally, two stainless steel pins (10 cm long, 5 mm in diameter) (3-1) are fitted through 6 mm holes at the two edges of the ruler (3-4) to hold the ruler rigid on the soil surface while sampling is underway. The ruler weighs 2 kg.