Supporting Information Effects of Tensile Stress and Soil Burial on Mechanical and Chemical Degradation Potential of Agricultural Plastic Films Yanan Han 1,2,3, Min Wei 1, Xiaoyan Shi 1, Dong Wang 1, Xulong Zhang 1, Yangyang Zhao 1, Meng Kong 1, Xin Song 1, Zhongkui Xie 2,3,* and Fengmin Li 1,* 1 State Key Laboratory of Grassland Agro-Ecosystems, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, Lanzhou 730000, China; [email protected] (Y.H.); [email protected] (M.W.); [email protected] (X.S.); [email protected] (D.W.); [email protected] (X.Z.); [email protected] (Y.Z.); [email protected] (M.K.); [email protected] (X.S.) 2 Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, No. 320 West Donggang Road, Lanzhou 730000, China 3 University of Chinese Academy of Sciences, Beijing 100049, China * Correspondence: [email protected] (Z.X.); [email protected] (F.L.) Received: 20 August 2020; Accepted: 24 September 2020; Published: 26 September 2020 Table S1. Results of repeated measure analysis of variance on nominal tensile strain at break, water contact angle, weight loss and tensile strength using burial time (BT) as the repeated factor and tensile stress (TS) and plastic film (PF) as two fixed factors within each of the two sites. Site Source Nominal tensile Water contact Weight loss Tensile strength strain at break angle df P value df P value df P value df P value Yuzhong TS 1 <0.001 1 <0.001 1 0.168 1 <0.001 PF 7 <0.001 7 <0.001 7 <0.001 7 <0.001 TS×PF 7 <0.001 7 <0.001 7 0.575 7 <0.001 BT 7 <0.001 2 <0.001 7 <0.001 7 <0.001 BT×TS 7 0.017 2 0.013 7 0.134 7 <0.001 BT×PF 49 <0.001 14 <0.001 49 <0.001 49 <0.001 BT×TS×PF 49 0.085 14 <0.001 49 0.276 49 0.003 Dingxi TS 1 <0.001 1 <0.001 1 0.277 1 <0.001 PF 7 <0.001 7 <0.001 7 <0.001 7 <0.001 TS×PF 7 <0.001 7 0.005 7 0.939 7 <0.001 BT 7 <0.001 2 <0.001 7 <0.001 7 <0.001 BT×TS 7 <0.001 2 <0.001 7 0.707 7 <0.001 BT×PF 49 <0.001 14 <0.001 49 <0.001 49 <0.001 BT×TS×PF 49 <0.001 14 <0.001 49 0.521 49 0.086 Figure S1. Tensile strength (MPa) of plastic films exposed to tensile stress or no tensile stress, measured at intervals up to 30 months after soil burial. PEF (polyethylene film). OBDF (oxo-biodegradable film). BDF (biodegradable film).. BDF dropped rapidly to an undetectable level by the end of 15 (for BDF1 and BDF2) or 24 (for BDF3 and BDF4) months. nTS+SB (no tensile stress and soil burial). TS+SB (tensile stress and soil burial). .