The invention includes a fixation element, an adjustment element and a drainage water-permeating element. The fixation element includes a first combination part combined to a pot body, a containing region utilized for placement of the drainage water-permeating element, and a second combination part utilized to assemble with the adjustment element. The adjustment element includes a penetrating channel that is capable of being sleeved in the drainage water-permeating element and communicated with the containing region of the fixation element and a position limiting part that is capable of being assembled on the second combination part of the fixation element. The drainage water-permeating element, which is located at the containing region of the fixation element and the channel of the adjustment element, is formed by a plurality of mutually-assembled particles, and the adjacent particles therebetween are provided with micro conducting channels that are mutually communicated. With the above-mentioned structure of the invention, a maximum water-permeating humidity range in soil can be adjusted, in accordance with a linear or rotational motion function generated between the position limiting part of the adjustment element and the second combination part of the fixation element to change a depth position of one end of the channel of the adjustment element located at an outside of the drainage water-permeating element.本發明包括有:一固定件,其具有一結合於盆體的第一結合部、一可供引流滲水件置放的容置區、以及一可供調整件組設用的第二結合部;一調整件,具有一可套置於引流滲水件內的貫穿通道、以及一可組設於固定件之第二結合部上的限位部,而調整件之通道係可與固定件之容置區呈連通;一引流滲水件,其係由複數個粒子相互組合而成的,且使相鄰粒子間會形成相互連通的微引道,並使引流滲水件能位於固定件之容置區及調整件之通道上;藉由上述構造,利用調整件之限位部及固定件之第二結合部間產生的直線運動或旋轉運動作用來改變調整件之通道一端位於引流滲水件外側的深度位置,進而作為改變土壤內的最大滲水溼度範圍之依據。3...固定件30...第一結合部31...容置區32...第二結合部38...油封4...調整件40...通道41...限位部45...扳動部5...引流滲水件50...粒子50’...粒子51...微引道
