Water conservation policies in agriculture, the largest consumer of water, are unlikely to succeed unless farmers voluntarily engage in water conservation behaviors (WCBs). Effective measures to reduce agricultural water consumption include cultivating low-water consumption (LWC) crops and adopting modern irrigation systems (MIS). Therefore, identifying the socio-psychological drivers influencing these WCBs and analyzing their distinctions are critical policy considerations for promoting sustainable water conservation actions. Hence, this study aimed to: (1) Explore the intentions and behaviors related to farmers' adoption of LWC crops and MIS, identify key determinants, and comparing them; and (2) Extend the Theory of Planned Behavior (TPB) by incorporating information publicity and personal involvement as social factors, and evaluate the robustness of this extended TPB (ETPB) compared to the original TPB in explaining farmers' WCBs. A cross-sectional survey and face-to-face interviews were conducted with 280 farmers living in Ardabil plain, Iran, and Structural equation modeling (SEM) was employed to analyze the data. Findings from ETPB revealed that information publicity was the dominant predictor of farmers' intention to adopt LWC crops (β = 0.65). Conversely, perceived behavioral control was the most significant predictor of farmers' intention to adopt MIS (β = 0.37). In terms of actual adoption, personal involvement (β = 0.41) was the strongest determinant for adopting LWC crops, whereas intention (β = 0.46) was the dominant predictor for adopting MIS. The ETPB model demonstrated a notable increase in predictive power. Specifically, it showed a 79 % improvement in predicting intention and a 31 % improvement in predicting behaviors for adopting LWC crops compared to the original TPB. For adopting MIS, the ETPB model exhibited a 25 % increase in predicting intention and a 5 % increase in predicting behavior.