Technical Abstract: The stability of resins used in organic matter mineralization studies is not well known under various physical environmental conditions. The objective of this study was to measure the changes in N and P adsorption and desorption by resins subjected to freeze-thaw or wet-dry cycles. Mixed bed resins (1:1 anionic-cationic by weight) were subjected to 1, 3, 10, and 30 freeze-thaw or wet-dry cycles. The wet condition was set to field capacity (FC) at 0.33 MPa and the dry condition was set when resins reached 70% FC. Wet resin was kept in forced-air oven at 27 oC for 28 h and rewetted to FC for 20 h. Resin at FC was frozen for 16 h and thawed to room temperature for 8 h daily. Alternating and prolonged cycles of freeze-thaw or wet-dry did not change the stability of resin. Freeze-thaw cycles did not induce N and P desorption from resin, however, wet-dry cycles induced desorption of N and P associated with shrinkage of resins and expulsion of interstitial liquid. Scanning electron microscopy revealed that environmental conditions did not physically alter the surface of these resins.