Comparative soil organic matter prediction in Chinese mollic-phaeozems and Argentine chromic-phaeozems using a colorimeter and portable X-ray fluorescence - Jun Jiang; Feng Zhang; Kang Tian; Le Jian; Wenyou Hu; Yiyi Deng; Zhimin Tang; Yiping Zhu; Diego S. Fernández; Daniela C. Villegas; Biao Huang (Geoderma Regional, 2026)